Conference 7.286::home_work

    We have a furnace about 18 yrs old made by Johnson Controls.
    It is gas with a blower motor. The problem I have is that with
    the temperature set between 62-65 it will come on several times
    in the middle of the night, and when the flame goes off, it will
    sometimes suck the pilot flame out. The Gas co has beenout three
    times, and cannot find what causes it. It has done it while they
    watch. It doesn't do it at any other temperature setting.
    
    They replaced the cupler, and the part where the gas comes out on
    the pilot, and checked the thermostate. Nothing.
    
    Anyone have this occur? Any ideas would be helpful.
    
    Hope I've explained this clearly
    
    thanks
    Gary

    Maybe you need one of those draft control devices that goes on the
    flue (or maybe it just needs an adjustment).
    
    Probably what is happening is that the remaining hot air in the
    flue is causing a suction within the burner unit.  What you want
    to happen is have the suction open the draft control and suck
    the air out of the basement.
    
    -al

    
    
    I had a similar problem last year. I have both a gas fired boiler
    and gas water heater. Some times one went out and somtimes they
    both would. There is a valve directly off of the meter which allows
    some air to mix with the gas and on this valve there is an air inlet
    pipe which extends out side through the wall. Our problem was that 
    the air inlet pipe, which is threaded, was pushed down allowing
    water to enter the air valve. This water caused the valve to
    malfunction.
    
    wayne 

    Well, the gas co. came out for the 4th time last week. This time
    the supervisor came along. I think they finally have it. 
    
    The last guy opened the dampers too much, put in the wrong size
    coupler, and had the pilot too low and the gas too high. Not bad
    huh?
    
    He actually made the problem worse. However, it's been fine for
    a week, knock on wood.
    
    Thanks for the advise.
    Gary

    I've had problems with the pilot light going out in a gas furnace.
    There were two reasons for this happening:
    	- The gas company made a fresh batch of "natural gas" and the
    pressure surge caused the pilot to go out
    	- I had a defective thermocouple. When it was replaced the problem
    went away.

    How does the gas company make a fresh batch of gas?
    Natural gas is just that it is in a gasious state when produced
    from the ground.
    Also the pilot light should have an orfice to limit the flow
    preventing a pressure surge for blowing it out.
    -j
    

    
    re .5
    Natural gas is shipped and stored in a liquid state. Before final
    distrbution, it is allowed to expand to a gaseous state. Perhaps
    .4 was referring to the utility's process of gasifying the gas
    as 'mixing a new batch'. Also, being a product of nature, natural
    gas can vary greatly in thermal energy content. The utility might
    have been blending different batches to produce a mixture with some
    standard therm value.
    
    An orifice meters gas to a flame, assuming that there is constant
    pressure on the supply side. A pressure surge would not be controlled
    by the orifice, and could blow outh the flame. The pressure regulator
    at the gas meter should take care of surges from the utility,
    establishing a constant pressure within the house pipes.

    The utility also adds some type of ODOR to the natural gas as
    it has little if any SMELL when it comes from the ground
    as TRUE NATURAL GAS. The ODOR addition is a safety precaution.
    Maybe this is the 'mixing' referred to.
    
    M

    I based my question on what i have learned from my father whom is
    an eng. for the local gas company.
    Natural gas is in liquid form only for overseas shipping and is
    not kept in a liquid state by utility companies the cost of doing
    so would be far too high. Instead the popular method for storage
    is underground in rock and pumped out to meet demand.
    The problem sounds like a regulator the pressure should be 3 1/2
    inches of water.
    BTW- the oderant is added constantly and is metered into the gas
    in the distribution lines. It is very highly concentrated and
    a half cup poured onto the ground is enough to produce a "gas smell"
    covering about fifty square miles. Natural gas may/maynot have a
    smell of its own before adding the oderant it all depends on such
    thing as sulfur content,ect.
    I stand corrected on the orfice it would do little to prevent pressure
    surges from causing the flame to"pop out". Thats what i get for
    twisting details in my mind.
    -j
    

	After having read all of the other topics concerning 
	furnace and water heater questions, a question that I 
	have is yet to be asked.

	This may fall on a lot of deaf ears in New England (due 
	to the high percentage of oil users), but I have 
	confidence that a lot of you have gas, also. :^)

	Here in Michigan, I have FHA by gas and a gas water 
	heater.  Both of the burners have pilot lights.  Now, 
	for the question:  Have any of you ever heard of a 
	retrofit that can be installed to make them pilotless 
	ignition?

	A recent state law mandates that all new gas burner 
	units must be pilotless, so I know that I could buy a 
	new furnace and WH.  However, I think that this would 
	be an unneccessary expense, considering the reasonably 
	good condition of my current units.  I just want to get 
	a little better efficiency by not burning gas during 
	the "off" times.

	Thanks for your help,
	SAS

    
    Steve,
    
    The Jan.'87 issue of Consumer Reports had a write-up on super efficient
    heating and hot water heating systems, and I know they talked about
    pilotless systems.  I'll check the article, and reply again.
    
    I do remember though, that you can purchase heating systems with
    efficiency ratings in the 90's.  But you have to PAY for efficiency,
    unit costs are on the order of 3 times that of regular systems.
    
    CU also gave a formula you could use to calculate if it would be
    cost effective for someone to buy one of these, or how long it
    would take to be cost effective.
    
    Steve
    

     I have seen kits to refit gas furnaces to pilotless ignition. i
    can't tell you where to look since I'm from Mass. Also, the kits
    may not be available for every brand of furnace. I believe that
    it's not possible to refit a gas water heater. (can't imagine why)
    
    					Kenny

    How does "pilotless ignition" work?  Does it require electricity?
    What if the electricity/battery fails?!  
    
    	Rick
    	Merrill
    

    I have a pilotless gas furnace.  The starter is electric.  If the
    power fails (or if it's shut off) there is no demand for heat so
    the furnace doesn't try to start.  
    
    					KO

    Re: How it works.
    
    Pilotless system is based on a pizeo-electric igniter. The system
    is actuated with a solenoid, striking the pizeo element. In turn,
    the pizeo crystal oscillates and generates a 2 to 5 kilovolt spark
    that ignites the natural gas (much like the spark plug in your car).
    
    I am not totally how the pizo-electric works. The pilotless gas
    stove has a clicking sound when it starts to ignite the surface
    element. I believe that the thermostat actuates a electric gas valve
    that turns on the gas for the igniter to work.
    
    In California, by turning off the pilot gas, we saved about $5.00
    per gas appliance (water heater, stove, oven, and furnace). We usually
    turned off the pilots to the stove and the furnace from April through
    mid-October. Here in Colorado, we leave the pilot on the furnace
    on. I'd like to install a pilotless system on the Lennox furnace
    that we have, when I find one.
    
    /cal hoe

    Not all pilotless systems are pizeo-electric (sp?) based. The new
    Amana high efficiency furnaces use a glow coil. The glow coil turns
    bright orange while heating (actually lights up the basement a little)
    and a circuit senses the temperature of the coil. When the coil
    is hot enough the gas is turned on.
    
    I just took out my old gas fired hot air furnace an put in one of
    these Amana units. Very nicely made. My father, who installs furnaces
    for a living, is even impressed with them.
    
    Nick

Retro-fit IID's (intermittent ignition devices) are not approved for use in 
Massachusetts. I have FHA by gas too, and just went from a piloted furnace to a 
pilotless one with flue damper. Payback is mighty long, but the old furnace was 
noisy and too small to heat the whole house.

Flue dampers are only permitted on furnaces designed for them, that have a
double-interlock to ensure that no gas flows if the damper is closed. 

-scott

    W.W.Graingers, a national distributor, carries two types of gas-pilot
    to electric-light conversion systems:
    
    1.  Dayton gas pilot ignition system (WWG stock # 2E563/2E564) for
        price range of $182 to $234.  They use 24V control with pilot
        flame burning only during periods when heating system thermostat
        calls for heat.  A solid state igniter is used.  Kit includes
        pilot igniter, electrode assembly, ignition cable with connectors,
        plug-in pilot switch and flame sensing element, 3/4" x 3/4"
        335,000 BtuH dual gas valve gas control, 1/2" bushings, 3/8"
        bushings and misc hardware.
    
    2.  Honeywell intermittent gas pilot system --  uses gas only when
        system calls for heat; is lit by high voltage capactive discharge
        spark, turns off automatically when demand for heat is satisfied.
        Includes prewired intermittent pilot module; universal igniter-
        sensor assembly, 1/2" x 3/4" high-capacity dual valve gas control
        with reducer bushings, ignition cable and misc hardware.  Prices
        range from $220 to $284, depending on natural, LP, full off/on
        models.
    
    
    
    BTW, sounds like you folks in MA have a lot of strange laws to cope
    with when DIYing.  Guess I won't consider transferring there.
    
    
    Happy in Cleveland with the Lake that is Erie
    Randy
    

    
    	I have an oil forced hot air system that I want to hook up to
    my new addition. I already have the ducts in the new room but I'm
    unsure how to hook to my furnace. There is a heating pipe going
    right past the new duct. Can I buy a Y pipe and connect to it or
    should I go directly to the furnace housing. I have never seen a
    Y connector so I'm assuming there not made or that is the incorrect
    way.
    
    	-Steve-
    

    Depending upon how the rest of the system is set up you might be
    able to get away with cutting it into the side of the existing
    supply duct. Chances are that you could unbalance the air distribution
    to the other rooms. It is very hard to determine this without
    seeing the whole system. I'd suggest running the new duct back to
    the supply chamber on top of the furnace if you're not sure.
    
    If you've never done this type of work before you probably won't
    have the tools that you need to metal ductwork with. They are pretty
    special purpose and not readily available. Why not have a sheet
    metal shop come over and give you an estimate?
    
    Nick
    
    (ex-sheetmetal mechanic)

    I'd like to try reopening this note.
    
    I had the gas company out today to check out my FHA furnace before
    the heating season starts and found out that my heat exchanger is
    cracked to the point that you can see the flame inside the tubes.
     Since this can add nasty things like fumes like carbon monoxide
    to the circulating air I'm also now in the market for a new furnace.
    Anyone have any ideas on what things I should look for in a new
    furnace?  Is installation something for the DIY'er (it's natural gas)?

    The latest issue of Practical Homeowner has a section on high 
    tech furnaces.  They seem to like the Lennox Pulse.
    
    -al

    I went out and looked at furnaces this weekend.  The two I'm
    considering are a Heil and a Magic Chef.  My current furnace is
    a 100,000 BTU but since I'm going to add heat to the basement I'm
    going to upgrade to a 125,000.  After seeing the prices on them
    I've decided to not go with the extra cost of the high-efficiency
    units.  For almost 1/2 the price I can get a unit with 78% efficiency
    vs the 95% of the high efficiency unit.  It would take a long time to 
    save enough for the unit to pay for the difference.  The 2 furnaces
    I'm considering are a Heil and a Magic Chef.  Anyone have any
    experience with either of these?

    
    	I have a Magic Chef 125,000 BTU that was installed about 1 year
    ago. Works OK.
    	-Steve-
    

    I have a question about adjustments on a FHA gas furnace.
    
    I just finished installing a gas FHA furnace and everything is working
    fine except that the air that reaches the living spaces doesn't
    seem to be very warm.  I slowed down the blower speed but that didn't
    seem to help to much.  I think the problem is that the fan is going
    on too early and not allowing the heat exchangers to really heat
    up.  When I looked at the installation manual it said to adjust
    the fan limit controls to a satisfactory comfort level.  Just below
    that in big highlighted letters it said "CAUTION, FAN LIMIT CONTROLS
    ARE PRESET AT FACTORY - DO NOT ADJUST"     Arrggghhhhh.....
    
    These controls are the ones that set the temperatures that the fan
    goes on and off at.  The only danger I can see is that the "on" control
    is set so high that the fan comes on only after the unit has gotten so
    hot that it is a fire hazard.  With this in mind I adjusted the
    control so that the fan comes on at 130 degrees.  That helped a
    lot and the air coming up through the ducts is a lot better but
    still could be a little warmer to my liking.  How high can the "on"
    temperature be set and still be safe?  Is there something I'm missing
    and should I just leave these controls alone?
    
    Thanks,
    
    George

I just went through this on my system - there are really 4 settings to 
play with:

3 On the furnace: (in increasing order)

fan-off temp
fan-on temp
furnace-off temp.

WHen the thermostat calls for heat, the furnace comes on, when it 
reaches fan-on temp, the fan comes on, when it passes furnace-off 
temp, the gas turns off untill the temp falls back below furnace-off 
(I think).  When the thermostat shuts off, the fan runs until fan-off 
temp is reached before shutting off the fan.

My settings are

fan-off temp		100F
fan-on temp		150F
furnace-off temp.	250F <-cannot be increased - anyone know why?

This seems to work adaquately well.

4) On the thermostat is a hysteresis control - I had a problem in that
this was set too fine - so that by the time the fan came on, the
thermostat stopped calling and the burner shut off - thus cold air
thru the ducts.  I've been told this has to be 'matched' to the
current rating (in amps) provided by furnace - but this usually gives
too tight a range for me - you might want to try increasing the
hysteresis until you feel its running comforably - that's what I had 
to do.

Other comments?  I'm still futzing with mine	/j

Re .1
    
1> fan-off temp		100F
2> fan-on temp		150F
3> furnace-off temp.	250F <-cannot be increased - anyone know why?


    1)	100F leaves a lot of heat still in the furnace/ducts. I adjusted
    the fan-off switch at about 75F. Works fine, puts more usable heat
    where we need it.
    
    3)	I don't know. Is this a trick question??
    
    
Richard

    If your furnace is one of the high efficiency ones, the fan comes
    on early to get air circulating through the air preheat (from the
    exhaust heat recovery) before the air is passed through the heat 
    chamber.
    
    Other problems are the length from the furnace to the air registers.
    There is a volume of air that has to be moved out of the ducts before
    the heat comes through. I have a fan control switch to keep my blower
    on so that air is always moving through my furnace, hot or cold.
    I have an electronic filter and a hudmidifier in the furnace and
    the air movement keeps the amount of cold air in the duct at a minimum.
     
    The fan speed control is one of the types used for the ceiling fans,
    and I hooked it to the slowest speed of a four speed furnace blower
    motor. You will find that filtering the air with air filters will
    reduce the amount of dusting that you or your spouse have to clean.
    
    /cal hoe

>Re .1
>    
>1> fan-off temp		100F
>2> fan-on temp		150F
>3> furnace-off temp.	250F <-cannot be increased - anyone know why?
>
>
>    1)	100F leaves a lot of heat still in the furnace/ducts. I adjusted
>    the fan-off switch at about 75F. Works fine, puts more usable heat
>    where we need it.
>    
>    3)	I don't know. Is this a trick question??

These setting reflect the position of stops on a mechanical 
thermostat.  Accuracy of 25% not guaranteed.  (The air is cool when 
the fan shuts down).

Not a trick question - I'd like to defect the 'lock' and push it up 
hotter - question is - what is my risk (house fire?)

    I'm considering replacing my electric furnace with a gas one.  The
    gas company quoted a price of around 5K (installed).  This is a
    "little" too high for me.
    
    Has anyone had any experience installing a gas furnace?  What does
    a typical high-efficiency gas furnace cost?

    I believe that one problem you would have is shortened life on the
    heat exchangers by letting them get too hot. The metal gets pretty
    brittle after a while.  The return duct on my old furnace was about
    1/3 of the size it should have been so I didn't get enough air
    circulation.  Differrent problem but same result - heat build-up.
    The heating people I spoke to believe that this played a big part in
    the exchagers cracking.

I'd be wary of fiddling with the burner shutoff temperature. If you screw
up, you could get lucky and at MOST damage the furnace; if you DON'T get
lucky, you could cause a fire - and it'd be intriguing to see if your insurance
company will pay up given you have mucked with a control marked "DO NOT
MUCK WITH ME".

Does the air EVER get warm at the register you are referring to?

If NOT, you should consider insulating the ducts (as long as air coming
out SOMEWHERE gets hot).

If it eventually gets hot, then the issue isn't with the furnace fan, it's
the duct's contents of cool air you're feeling. Even the coolest fan-on
setting should ship air that feels "warm". Air that's just moving at ambient
temperature feels cool.

An earlier note mentioned keeping the fan on at all times as one way to
make things more comfortable. Some more experience:

I have a humidifier and an electronic air cleaner on my furnace. I recommend
both highly. The humidifier comes with a humidistat (humidity sensing switch)
that installs in the return air plenum, senses return air humidity, and
switches on the humidifier when humidity is needed. I added a pair of relays
to make the following change: Whenever the humidity sensed is too low, Turn
On the furnace blower at it's slowest setting UNLESS it's already running.

Note that most furnace fan motors have several "speeds" (windings) that
you can chose from, so you may not need to consider a speed control. the
wiring "looks" something like


*----------*     *----* Humidifier ---*
|Humidity  |     |                    |
|Sensor    |-----*----* Relay #1 Coil *------Neutral (WHITE)
|(Closes   |
|if too dry|---------------------------------110V (BLACK)
*----------*    
                
*----------*
|Blower    |
|High Speed|---------* Relay #2 Normally OPEN contacts *------110V (BLACK)
|Winding   |
*----------*

*----------*
|Blower    |
|Low Speed |-* Relay #1 Normally OPEN contacts *
*----------*                                   |
                                               *Relay #2 Normally CLOSED* 
                                                      Contacts          |
                                                                        |
                                                                       110V
*----------*                                                          
|Present   |
|Furnace   |---------* Relay #2 Coil *------------------------Neutral (White)
|Connection|
|to Fan    |
*----------*

I used two 110V-coil relays - #1 is Single Pole Single Throw (SPST); #2
is Double Pole Double Throw (DPDT) rated at 15A (more than enough for the
motor windings; same ratings as those in the furnace).

What all that does is lets the humidistat turn on the furnace fan at its
lowest fan setting whenever the house needs humidity, but allows the fan
to run at its high setting - the humidifier runs whenever it's needed at
either fan speed.

Relay #1's job in life is to "know" that humidity is called for; relay 2's
job in life is to decide whether the furnace fan should run at High Speed
(the furnace wants the fan on) or Low Speed (only the humifier wants the
fan on). Relay #2 also prevents both fan windings from being energized at
once.

I have tried keeping the blower on at slow speed at all times - costs mucho
bucks in KWH.

Dennis

Note - many of the multi-speed fans draw the same energy regardless of 
speed.  They just run less efficiently at the lower speeds. -

I was thinking of doing the reverse of what you mentioned - my 
humidifier (on my central FHA system) runs continually, governed only 
by the humidistat.  My heat is OFF for several hours each day, and 
turned down quite a bit at night.  This suggests that the humidifier 
will run for a great deal of time when the fan is off - does this do 
me any good? any harm?  Was thinking of wiring it so the humidifier 
runs ONLY when the fan is on - ?????

			/jeff (who has left the max temp of his 
				furnace at factory setting)

I'd guess that running the humidifier with the furnace fan off would do
a heck of a job of getting the ducts wet - do you have a belt-type/evaporative
humidifer or is it a mist-type? If it's the mist type, you probably ought
to wire it in to the furnace fan circuit so it won't soak the ducts. If
it's evaporative, it's less of an issue - all it will do is raise the humidity
in the ductwork near the unit.

Either way, not much point in running it when the fan's off....

Dennis

   ---> From .1 <---
     
>  When the thermostat calls for heat, the furnace comes on, when 
>  reaches fan-on temp, the fan comes on, when it passes furnace-off 
>  temp, the gas turns off untill the temp falls back below furnace-off 
>  (I think).  When the thermostat shuts off, the fan runs until fan-off 
>  temp is reached before shutting off the fan off.

    If your FHA system is working properly, the burner should never
    get turned off on account of the furnace-off temperature being reached.
    (This may not be the case for the pulse-type systems, I don't know.)
    The circulating air should keep the heat exchanger temperature below
    the furnace-off temperature.  The burner should only have to turn
    off when the thermostat's demand is satisfied.  The high-limit 
    (furnace-off) should only come into play if:
    
    	1)  The fan never came on.
    	2)  Insufficient return air is available.
    	3)  The hot air has nowhere to go, registers shut.
    	4)  For any reason the burner is generating more heat than 
    		the fan and/or rest of the system can deal with.
    
    The settings for my FHA system are:
    	Fan-on:      120   <--- Fixed, can't be adjusted.  Also has
    				a timer that will turn the fan on in case 
    				the temp. sensor in the switch fails.  
    	Fan-off:     110   <--- Adjustable with a screwdriver at the fan-limit
    	  (Low-Limit)	        switch.
        Furnace-off: 220   <--- Fixed, can't be adjusted.  The heat
    	  (High-Limit)		exchangers in home FHA systems frequently
    				have a maximum operating temp. of 200.
    			
    I recently had the fan-limiter (camstat) replaced on my FHA furnace.
    Its problem was that the fan-off (low-limit) took forever to shut the fan
    off; once it came on it would run for hours or until I killed
    the power to the furnace.  The Gas Company tried 4 new switchs with 
    adjustable high-limit off controls.  None of them (same kind) worked.
    In each case the furnace burner would cycle on for 1 min. then off for 
    1 min. then on for 1 min. etc... until the thermostat's demand for 
    heat was satisfied.  What was happening was that the high-limit
    circuit was getting energized even though the temperature was still 
    below the high-limit.  The switch they tried last worked.  It had a 
    fixed high-limit (like the one they were replacing except the new 
    switch's high-limit was 220 while the old switch's high-limit was 240).

Well...this is the 3rd place I've lived with FHA heat, and on all of 
them the burner would cycle (though with low frequency) when the fan 
was on - but only if you were calling for heat for a while.

I think some systems may be designed this way (energy efficient?  
faster heating?) 

    Make it six - the apartment on the first floor of the building I'm
    in has gas FHA. Their furnace is in the basement, where I am, so
    I can hear it - the burner cycles on and off while the blower runs.
    -Tom R._who_will_have_wood_and/or_FHW_in_his_half_of_the_new_duplex

    5K seems pretty steep, especially if the ductwork is already in place.  I
    just replaced an old steam boiler (oil) with FHW (gas) and in the process
    looked into gas furnaces.  I think the higher efficiency models (100K BTU)
    cost around $1000.  You should probably get a few more estimates
    before making any decisions.  I was quoted a 6K figure by the Nashua, NH
    gas company and that included replacing the entire boiler and all the
    the pipes and radiators.

    Anyway, I think it should be fairly easy to replace a furnace yourself.  I
    found a couple of places, Total Air Supply and Masi's, in Nashua that would
    sell me a furnace and ductwork along with a plan of how it should be all
    layed out.  If you are inexperienced at this like I am, it is important to
    purchase your furnace from some place that will be able to answer your
    questions.  It may be necessary to have some custom ductwork built to
    connect the new furnace to the present ductwork.

    A couple of other things to think about are wiring the furnace and running
    the gas lines.  I hired someone to do them for me due the fact that it was
    getting cold and I was running out of time.  Another problem for you may be
    the chimney.  If you don't have a chimney available, I suggest the very high
    efficiency furnaces that can be vented through an outside wall with PVC
    pipe. 

    Good luck,

    Joe
    

	Sunday the power in my section of Nashua went of twice.  It
    was only a couple of minutes each time but it was long enough for
    me to realize that even though I have gas heat my nice new FHA
    burner with the electronic start is useless with no power.  Does
    anyone know if it's possible to hook up some sort of external power
    source like a battery to handle such emergencies?  I realize a
    generator would be a perfect answer but I don't want to spend that
    much money and all I really want is enough power to keep the furnace
    going.
    
    Thanks,
    
    George

    
    
    	It would cost more for the batteries and converter then it would
    for a good Honda generator. The batteries you need are called Deep
    Charge Marine batteries which cost about $100 a piece. I can just
    imagine how many you would need. A furnace has a capacitor type
    start system which requires a surge of electricity to get the burner
    going. The converter would be very expensive also.
    
    
    	-Steve-
    

Besides, it probably wouldn't be useful (or maybe even safe) to have the 
burner cut in on your FHA furnace when you have no power for the 
blowers.  You need a generator or a woodstove to see you through those 
power hits.
					>>>==>PStJTT

Just bought a Honda generator for exactly the same reason.  One 
problem with FHA is that the furnace fan STARTING current can be like 
15A.  Elsewhere in this file (check 1111.x under electrical) is a note 
on generators, and a more detailed one in OVDVAX::ELECTRO_HOBBY.

In a word - you can get industrial (read noisy, need some expertise)
generators for as low as $400, or idiot-proof Honda generators for
about $800. 

    I have a central-heating gas furnace.  It is installed in a closet.
    (I live in the Los Angeles area, so the furnace is small.)
    The furnace is held off the floor by a plywood board.  Part of the
    furnace is below this platform and part of the furnace is above
    this platform.  Thus the furnace passes through the wood board.
    However, the wood board does not fit snugly around the furnace.
    There is gap in one area.  The gap measures about 1" x 12".  The gas
    company says I must seal this gap, or carbon monoxide could get
    into the house.
    
    They say I need to cut a piece of wood the size of the gap and somehow
    fill up the gap with it.  Now, if the piece of wood is slightly
    smaller than that size, the piece will just fall through to the
    floor.  On the other hand, if the piece of wood is slightly larger than
    the gap, it won't fit in the gap.  What is my best strategy for closing
    the gap?  Make the piece of wood slightly smaller than the gap and
    smother the edges with glue?

make it slightly smaller, put a metal brace or 2 under it (or over it) 
to hold it there, and fill the cracks with caulk or mortite

    Before you seal off the gap, check to see about access to your furnace
    filter. My girl-friend's house in San Jose was built on a slab and
    the furnace was mounted just as you described, with the cold air
    return underneath. The burner area was seperated from the air return
    area with the same gap so that we could get the filter out. I believed
    that the furnace was modified by the contractor to fit the house.
    
    If you close off the gap, make it removeable.
    
    /cal

"Mr. Moderator" (e.g., Paul, DCL) _ I checked 1111.35 and couldn't find a good
home for this.  Please correct me if I'm wrong.  If its a real concern, it 
might be worth a new note anyway?  Thanx /jeff 
================================================================================

I <thought> my gas FHA furnace was in great shape, even though its 25 years
old.  The outboard motor for the belt-drive squirrel cage fan has been
replaced recently, and the burner itself seems to heat up a storm... 

Until someone recently mentioned that this could all be ok, but due to some
unseen crack or defect in the burner it could be emitting a hi-level of
noxious fumes (CO?) 

		anyone more expert on this than I??? 

thanx/j

    A crack in the heat exchanger part of the system can allow CO to
    enter the system as it is the only thing seperating the combustion
    gasses from the air passing thru the heater. I have been told the
    way to check is to darken the room and shine a flashlight on one
    side of the exchanger while observing the other if you see light
    then CO could be passing thru into the system.
    
    
    -j

    Or you might be able to find the problem like I did.  Just go
    downstairs when the furnace is on and look through the grill at
    the heat exchanger.  The flames coming out were quite easy to see
    on mine.

    Hi,
    
    I just purchased a house that had a problem with the gas furnance.
    The inspection company put some burning substance(hemlock??) in
    the furnance, when the smell was carried through out the house we
    knew the the heat exchanger was bad.

>    A crack in the heat exchanger part of the system can allow CO to
>    enter the system as it is the only thing seperating the combustion
>    gasses from the air passing thru the heater. I have been told the
>    way to check is to darken the room and shine a flashlight on one
>    side of the exchanger while observing the other if you see light
>    then CO could be passing thru into the system.
    

what is the 'heat exchanger?  My furnace merely blows air past a set 
of lit gas jets (like the unit in a big gas oven) into the ductwork.

Interesting I should find this conference on my first full day as a
homeowner, and this note was started on the day I noticed my furnace-
to-be had a problem!  (Is it coincidence, or is it karma?)

Our final walk-through was this past Wednesday.  All through the house-
hunting process my nit-picking had aggravated everyone involved.  BUT
on this particular day I scrambled into the crawlspace and found what
the seller had "forgotten" to mention on the disclosure sheet, what
our "friend" who inspected the house missed, and what the appraiser
obviously didn't bother to find:

	A note was stuck to the side of the forced-air gas furnace
	with the name of a local heating company and the words,
	"Caution, this furnace has a cracked heat exchanger."

Well the seller called in an inspector, and we called in an inspector
(about $30 each) and they both said, "Yup, there's a crack.  Can't use
it, gotta buy a new one."  One of the guys doesn't even sell furnaces,
so he wasn't there to do a sales job on us.

The heat exchanger is kinda like a radiator in reverse -- the flames
and associated gases are kept away from the house air by keeping each
to its chamber.  If there's a leak, the combustion gases and unburned
gas (if that's what you're using) leaks into the house.  Bad news.

Wanting to make an expensive job cheaper, we asked if just the
exchanger could be replaced.  Nope.  It's too difficult to warranty.
Or the labor's not worth it, especially in a crawl space.  Or whatever.

To make a long and exciting (to me) story short, the sellers agreed
to replace the furnace.  They had to; the sales contract said they would
convey certain items to us in good working order.  (Oh yeah, the water
heater was leaking too.  But that was a simple pressure release valve,
and it was handled quickly and cheaply.)

The guy who doesn't sell furnaces had some interesting recommendations.
He works for a non-profit outfit that services about 700 furnaces a
year for the city's low-income housing.  He made a brand recommendation,
which is probably irrelevant.  And he said NOT to buy one of those 90+%
effficiency jobs.  Sure they convert more flame into useable heat, and
sure they save a few dollars a month by not having a pilot light, but
the payback just isn't there.

What happens is that the complicated electronics fail more frequently
than the old technology, and they're more expensive to repair.  For
example (he said) the ignition system on a no-pilot unit can run $400.

So, he recommends to the city that they buy old-style, reliable stuff.
This cuts the cost down from $1800-2000 to $900-1200 for us.  (And the
seller.  They had to take some proceeds from the closing and put it
in escrow for us to buy a new furnace with.)

ON THE OTHER HAND -- just to be perfectly fair I'll tell you what the
seller said.  The seller claims she was told by the guy who put the
sticker on the furnace that it was okay the way it was, that it didn't
have to be replaced.  (Something doesn't ring true here -- why did he
put the sticker on it?  Either to scare her into buying a new furnace,
or to cover himself because it really was dangerous.  Hmmm....)

So Jeff -- I'd say have it checked by someone with experience who you
can trust.  There's a lot at stake (health and pocketbook)!

					-- Ed

Gee, I was sort of hoping I could inspect it myself - anyone know if 
this is a good idea, and what to look for (still don't know what a 
'heat exchanger <looks like>, or do I need a pro (maybe they have
calibrated eyeballs? :-} )

    It shouldn't be difficult to inspect this yourself.  In the cabinet
    above the burners is a series of large metal tubes. These tubes
    enclose the burner flame.  On my old burner I could look through
    a grill at the exchanger and see the flames coming out through cracks
    in the tubes.  I was also able to remove a panel, one of the cabinet
    sides really, that covered the heat exchanger and could inspect
    it directly.  When the burner is on look for flames coming out of
    the heat exchanger or if you can get the exchanger itself look for
    cracks or holes in the metal tubes.  A REAL crude drawing of the
    set up I  had is below.
    
    George
    
    
    
    
	    			-------------------------
    		Cabinet	 ---->	|   ||====||====||	|
        			|   ||    ||    ||	|
        Heat Exchanger ---------|-> ||    ||    ||	|
        			|   ||    ||    ||	|
        			|   ||    ||    ||	|
        			|   ||    ||    ||	|
        			|   ||    ||    ||	|
    				|   /\    /\    /\      |
		Burners---------|-> /\    /\    /\      |
    				|    ====================
    				|_______________________|
    

    1.  If the heat exchanger is cracked, you're getting CO in the
        house.  It's not economical to replace the exchanger, unless
        it's still under warranty.
    
    2.  If you need to replace the furnace, MOVE FAST NOW because the
        contractors will become harder and harder to reach as the
        weather gets colder.  
    
    3.  There are alternatives between the "old standard" and the
        "super-efficient" -- Carrier (also carried by Bryant and
        others) makes one that is very similar to a standard, except
        for the heat exchanger design.  Instead of the straight
        vertical tubes running from the flame to the flue, they create
        an "S"-shaped path with about four turns, and add a fan to
        create draft through the higher resistance of the longer path,
        (It's called "induced draft" design).  Between this and the
        pilotless ignition, you get close to 90% efficiency.
    
    4.  Find out who services furnaces in your neighborhood.  In Boston
        Gas areas (Winchester, anyway), Boston Gas does no inatallations,
        but does all the service.  This screwy arrangement can easily
        leave you facing a service person who literally has no idea
        how to deal with your furnace.  Boston Gas even had some
        difficulty figuring out the "modest-tech" design I described
        in #3 above.
                   
    dq
    

[I've read 2646.* and this may belong there, so feel free to move it Mr. Mod]

Monday I started up Gas FHA system for the winter.  In the spring I turned
it off completely. (ie. turn the elec. as well as all the gas valves off).
Since I started it up on Monday, I have smelled a "funny" smell.  I'm not
sure if its gas or not, can't really distinguish what it is. 

My questions are: Is it "abnormal" for a gas FHA to give off a funny odor for a
while once being turned on after being shut down all summer?  It ran fine all 
last winter, and I certainly don't remember this smell last winter.  If 
something is amiss, what could have happened this summer (while it was 
shutdown) to cause the system to malfunction now?  Could it be the heat 
exchanger as mentioned in note #2646? Should I get my gas company out there 
ASAP or someone else who specializes in FHA systems?  Should I shutdown the 
system until I can get someone out there to verify that all is okay? Enough 
questions...hopefully someone will be able to answer some of them.

Thanks in advance
-Jim

PS: It's a Miller Gas FHA system, if anyone is familar with them.

	If the smell is musty, it is normal to get a musty smell for about 
	a day after firing up a FHA system, especially after a humid summer.

	If the smell like rotten eggs, smoke or oil, then their is something 
	wrong with your furnace.

	If it smells like something died, then probably some critter has gotten 
	stuck in you ducts.  Finding it will be difficult plus you have to 
	find and plug the hole used to get in.

	Other odd smells could be caused by recirculating odors from the 
	basement or utility rooms.

	Brian

    Probably just a summer's worth of accumulated dust in the ducts
    getting heated up and blown around.  It should go away in a couple
    of days.  If not, you may want to investigate further.
    

   Have you cleaned the filter?

re: .3

I'm not very familiar with these heating systems, so please excuse my
ignorance, but by filter do you mean the "mesh" that is on the inside
of the cabinet door, covering the vents that draw air in from the room?
If so, I cleaned this in the spring.

Is there any regular (annual?) maintenance that needs to be done on these
systems? Anything that is not a DIY and needs a service person?

Thanks again,
-Jim

On the other hand, my system gives off a slight 'heat' smell often 
when it turns on, just like the one did at my last place.  I think 
gas heat inherently can have a minor odor - or maybe it comes from 
starting to blow air thru the ducts.....

(on the other hand, maybe both systems had badly cracked heat 
exchangers, - except that the airflow would be FROM the air chambers 
INTO the flue)

    You don't by any chance get headaches do you???
    
    My 20 year old heat exchanger in my gas FHA rusted through
    during the *summer* a couple years back, blowing exhaust
    into the house. Though I never connected the 2 (headaches
    and furnace) together, other phenomena (pilot wouldn't stay
    lit) finally prompted me to have a repairman look at the 
    furnace. He pronounced it 'dead' and said summer was often when
    a rust-through occurs as the furnace could stay damp for an
    extended period of time...
    
    The headaches stopped immediately upon replacement.
    
    Edd 

    I've got a slight variation on the theme here...The pilot light
    stays on until I turn the gas valve to 'on'.  Then it slowly fades
    out.  Turning it back to 'pilot' brings it back.  Thinking I may
    have had 'on' and 'off' confused, I turned it to 'off' and the pilot
    light immediately went off.
    
    Is this something I should be messing with, or should I bite the
    bullet and call a repairman?
    
    Any ideas?
    
    Bob

    
     rep .9
    
     You have either a bad gas valve or thermocouple. My guess is the
    thermocouple. I had the same problem as you described and the fix
    was the thermocouple. If the gas valve is the problem you had better
    get a licensed repairman to fix it. I'm thinking od insurance problems
    if anything happens if you DIY.
    
    
      -mike
    
    
     

    re.8 & .9
    I second the thermocouple fixed mine too.
    
    -j

    Well, when I went home last night, I decided to give it one more
    chance and turned the gas to 'on'.  The pilot light stayed on. 
    Turned the thermostat to heat and got heat.
    
    I wonder, was that an early warning of a dying thermocouple, or
    just something strange?  I don't want to pay to have the thermocouple
    replaced if it isn't required.  On the other hand, we all know how
    much fun it is to track down intermittent problems :-{
    
    Should I make the call.
    
    Bob

    	Guy's and gals, what do you think about DYI, gas hot air furnace
    replacement.  My furnace is 28 yrs old and I have added on to the
    house and I feel that its no longer adequate to do the job.  I'm
    told that there have been some significant advances in furnace design
    w/ regards to efficiency.   It almost seems like it shouldnt be
    that bad of a job, so lets hear from some who may have done it or
    are contemolating doing it!!

                Jim
    

    
      rep .12
    
    	A new thermocouple is about $5 and is a DIY item. Most hardware
       stores carry them and they are for the most part universal. I
       just replaced the one in my two week old hot water heater over
       the past weekend. The thermocouple I bought at the local hardware
       store had all the nuts and clips I needed. From the symptoms
       you describe I would go ahead and change it. My hot water heater
       died saturday morning, I relit it and then it died about four
       hours later. Sunday morning it was dead and the mad rush to replace
       it began not a great way to start a sunday morning.
    
    
     -mike
    
      

    I have a Bryant (BDP) GAS FHA furnace.  I had been hearing chatter
(click, click, click...) when the burner ignited and then at sporadic
intervals during the heating cycle when the burner was lit.  I had the Gas
Company (Colonial Gas of Lowell) come out and take a look at it.  The first
set of technicians (two) that they sent cleaned the flame sensing probe. 
This had no affect.  The next technician that they sent out said the problem
was an end switch in the automatic-vent-damper unit (a Bryant manufactured
add on to the furnace -- not covered by my service agreement, which I
started last year after the fan/limiter switch failed).  The chatter was the
gas valve solenoid repeatedly openning/shutting the gas valve because of a
flakey signal from the automatic-vent-damper.  The technician said that the
part would have to be ordered and that it was expensive so why didn't I see
if I could live with it the way it was for a while.  The next day, when I
turned the thermostat up from a lower/night-time setting, all I got was
chatter -- no ignition.  So I de-installed the circuit for the
automatic-vent-damper, the result is the vent damper stays open (it is
powered shut) and the furnace burner ignites and stay lit with no chatter. 

    I intend on getting a quote from Colonial Gas on what the price of the
part is and what installation would run, but what I'd like to know first is:

      - How much does an automatic-vent-damper contribute to fuel savings?

      - How reliable are they?  (I've had this house for about 4 years now
	and the furnace is around ten years old, so my guess is that the
	current automatic-vent-damper is also about ten years old.)

      - What is the pay-back period or cost benefit to having an automatic-
	vent-damper (cost vs. fuel savings)?

    The last thing I wanted to mention is the fact that the furnace now
seems to be cycling more frequently, but for shorter periods of time.  It
keeps the house quite close to the temperature that the thermostat is set
at; although, in the past, I thought there used to be more over-shoot of the
set temperature (about 3 or 4 degrees).  I checked the heat-anticipator
setting on the Honeywell thermostat (it's the gold round type) and it is set
at 0.5 which is what the furnace documentation states is correct (this topic
is discussed in Note 15).  Could it be that the automatic-vent-damper was
allowing the furnace to capture that much more heat from each cycle?  At
this point I'm using the furnace's past performance as my reference point. 
Is it that the furnace is functioning correctly now (more frequent shorter
cycles) and it was not in the past (less frequent longer cycles)? 

    Anyone's comments or comparisions against their own furnace observations/
experiences would be appreciated. 

    Thanks, 

	--- Richard --- 

First, if you need  to  ask,  you  need the Gas company.  Safety first, and all
that.

That said, I have always worked on my  gas  appliances.    What follows is, for
simplicity's  sake,  a layman's, not_very_technical, description and will apply
generically to MOST gas appliances.

Most of the  problems  have  been  due  to thermocouples.  The thermocouple is,
essentially, a wire that  generates  an electric current when it gets hot.  The
end that mounts into the gas valve is attached to the coil of an electromagnet.
The thermocouple gets hot, generates a  current  and operates the electromagnet
which, in turn, operates a switch/valve to  permit  gas to flow through the gas
valve.  If the thermocouple cools off (very  quickly),  the switch "snaps" back
and shuts off the gas flow.  When you  light the pilot, you usually hold down a
button that operates the valve.  That is, you bypass  the thermocouple.  If the
thermocouple does not get long enough as it heats up, the  valve  will not stay
open when you release the button.  

Thermocouples are inexpensive and easy to replace.  When I  have  a  problem, I
replace it and hope it is fixed.  Since they ALWAYS  go  bad  on a cold, winter
Sunday am, I keep a couple around.

The next problem area  is  the  previously mentioned electromagnet switch.  The
real problem here is that  they  usually last years (or decades, even,) and you
cannot find a replacement when you  finally need one.  You wind up buying a new
gas valve ($100+++).  Sigh...

Finally, the gas valve can go bad for numerous reasons  and  I  never recommend
anyone try to fix one.  For one thing, you seldom  can find the necessary parts
for the same reason as above.  Replacement is easy, but, again, if you have  to
ask, pay the labor costs.

A  common  problem  happens to those folks who turn off their pilots during the
summer.    There  is  seldom  a problem when you shut it off at the gas  valve,
however  if  you  shut it off further back down the line, you can have moisture
(condensation) get  into  the line.  Then, when you fire it up, the moisture is
pulled through to  the gas valve and causes strange symptoms like dying out and
coming back until the moisture is finally pulled out.  

Hope this explanation was worth the time.

Dave

    I replaced mine last year.  I was surprised how easy it was.  Be
    sure to get your new furnace from a place that is willing to answer
    any DIY questions you might have.  I found the people where I bought
    my furnace to be invaluable.  Where you're not just replacing the
    furnace but also increasing the heating capacity there may be some
    issues around cfm etc. that I didn't have to deal with.
    
    George

    re: .13, .14
    
    Thanks for the info.  I am familiar with how a thermocouple works. That
    is why I was confused when the pilot light would stay on, in the
    'pilot' position, but not when the gas was turned to 'on'.  I can't see
    the connection between turning the gas on, and the thermocouple.  The
    thermocouple will always turn off the gas if it cools off and the gas
    supply is not being held on by the spring-loaded bypass switch.  As
    long as the pilot light is on and heating the thermocouple, the gas
    should continue to flow and hence the pilot light stay on, regardless
    of the switch position. (Ignoring the 'off' position).
    
    Bob

    	Has anyone else seen the new round of ads sponsored by the New
    England Oil Heat Council?  It starts off with a simulated Gas company
    commercial stating:  If you smell gas call right away, but if you
    are having trouble with you heating system we'll get back to you.
    It then goes on to show what *wonderful* service you get with a
    full service Oil Dealer.
    	I guess it's time for the Oil vs Gas heating fights.  I don't
    mind the ads, it the Oil company's assertion, Get Gas, go BOOM
    that bothers me as misleading.
    					=Ralph=
    
    (Oil heat, gas dryer, hot water and stove)

    
    
    I also replaced my hot air furnace, its not that difficult, any
    sheet metal shop can make up the adapters for connection of the
    new furnace plenums with the old ducting. Where I bought my furnace
    they also did sheet metal work so it was easy. Dont forget to consider
    offsets as well as the diameters and heights, most likely the openings
    won't line up evenly due to the decreased size of the newer furnaces.
    
    One more thing to note there is some set up and nozel selection
    of the oilfired type furnaces for maximum efficientcy but if you using
    gas then I don't believe theres any. The set up of the oil burner
    is much what they would do in a professional cleaning, the selection of
    nozel for the oil gun is something the sales place should be able
    to tell you.
    
    good luck,
    
    Steve
    
    believ

    Just yesterday a house in Weston (owned by a lady who retired after
    40 years with Boston Gas) disappeared in a gas explosion.  A contractor
    was digging in her yard and ruptured a pipe close to the house.
    The basement filled with gas (the lady heard the sound and left
    the house) and then after less than 2 minutes, (how you say?) BOOM!

    	Thanx, folks for the replies, the more I hear the better it
    sounds.  I'm going to sart to get some prices for furnaces.
    
    

    
    When I had my new burner put in, I was told that it must be installed
    by a licensed burner technician. If the house burnt down because I
    installed it myself, I wouldn't collect a dime. Better check your
    insurance policy first.
    
    CdH
    
    

    Richard,
     
    You are now allowing fresh air to flow through your furnace and
    extract heat from your furnace, and shoot it right out of the chimney.
    
    You will notice a big-time difference in your gas bill very shortly.
     
    The reason you had over-shoot in your previous condition was that
    the furnace was indeed holding onto your heat longer and therefore,
    in a FHA system, the blower might always run until the heat exchanger
    cooled sufficiently. Now, your burner shuts off, allowing a rapid
    cooling  effect by the hot chimney causing an up-draft through your
    furnace. With the damper fixed, the recommended action would be
    to lower the anticipator a notch and go further is that still causes
    overshoot. 
    
    Fix your damper. If you are in field service, as a technical person,
    you should have no problem. (You bypassed the circuit already,
    correct?) The furnace burner control must see a "damper open" condition
    in order to sustain ignition. Your damper is doing one of probably
    only three things: 
    
    either the spring which opens this damper up has weakened, allowing
    the damper to flutter off of the open mark;
    
    or the micro-switch which detects wide open damper position is flakey
    and is in need of replacement or adjustment;
     
    or finally, the relay which switches the drive power to the damper
    motor is noisy and causing the damper to be driven at the wrong
    time. 
    
    You can find out for sure by ohming out the line that goes to the
    switch and the common line to the motor/switch and wiggling the
    damper while checking continuity there. If there's intermittance,
    the switch or the spring may be at fault. if there's no intermittance,
    then power on the furnace with all connections back to normal. Attempt
    to start the burner, and check the VOLTAGE to the torqueing motor.
    If there's any sign of 28 vac, then the relay or its decision logic
    could be at fault. I vote for a cruddy set of relay contacts in
    the control followed by a flakey switch in order of probablilty.
     
    If you need anything else, please send me VAXmail, as I don't get
    much opportunity to read this file (I'm a field service monkey,
    too!)
    
    Mike

    	I would like to install an outdoor air intake for my gas furnace.
    (This weekend, I realized just how much air I'm losing from the
    upstairs to the basement due to the combustion exhaust.  Wow!) 
    Two questions: (and Mr. Mod, I know the idea of an outside air intake
    was recently discussed, but I don't think these particular questions
    were discussed.)
    
    	1)  How large of an intake should I put in?  A 6 or 8 inch pipe
    would be do-able, but would I need a larger one?
    
    	2)  The inside part of the project looks real easy given where
    my furnace is and its orientation.  What do I put on the outside,
    though?  Do they make flapper valves (or whatever they are called)
    for 8 inch pipe?  And don't flapper valves require the pipe to be
    horizontal?  Wouldn't that let rain water in?
    
    	(Incidently, no, putting weatherstripping on the door at the
    top of the stairs isn't a viable solution.  I have my hobby room
    in the basement, so sealing off the upstairs would force the furnace
    to draw its air through the basement door and various airholes.
    I'd end up with a basement that is too cold to work in comfortably.)
    
    								-c

    My last house had an outside air intake. It appeared to have been
    installed by the previous owner. It was 6 inch galvinized duct pipe.
    The outside end was curved down and covered with window screen to
    keep out critters. 
    	I would recommend using a much larger diameter pipe. My furnace
    was in a small utility room with an accordian door. This room was
    entered through a larger room with an accordian door also. When
    the furnace turned on these doors were sucked in noticably.
    	I had a wood stove in the basement near these rooms. It was
    importand for me to open the door when lighting the stove, it was
    *vital* if the furnace was firing! If not I couldn't get enough
    updraft to prevent my house from filling with smoke! (Fortunately
    the one or two times I made this mistake I was able to use the whole
    house fan.
    	As a rule of thumb I would recommend an outdoor intake a bit
    larger than the exhaust stack of the furnace. Making it larger will
    compensate for the reduced airflow because of the screen you will
    want to cover it with.
    
    		Good luck
    		Mark
    

    
    	An update on the project.
    
    	I've decided to modify the plans.  Rather than put the pipe
    through the siding of the house (messy if the overall project
    fails...), I've decided to use a basement window as the air intake.
    (It is one of those casement windows around 30 inches long and 8
    inches high or so.  For the winter, I tape a rigid foam "plug" into
    the window to cut down on the heat loss -- so losing the window to the
    winter air intake is no big deal at all.)  The window, incidently,
    is close enough to the furnace that only around four/five feet more of
    ducting would be needed compared to poking the hole in the wall.
    
    	Before I begin the implementation of this, however, I'd like
    to ask one more question:  Are there any code requirements that
    I should be aware of in doing this???  Even though it will be carrying
    cold air, the entire assembly will be sheetmetal/ductwork just to
    be sure.  I'm planning on attaching it to the furnace via sheetmetal
    screws.  Is there anything else that I should be cautious/aware
    of?
    
    	Thanks!
                                          
    							-c

    
    Make sure that you won't ever get a snow drift filling up the window!

                                         
    Re: .3
    
    	Good point, and was another reason why I was hesitant to poke
    the hole through the wall -- that would leave the intake only around
    2-3 feet above the ground level.  My window, on the other hand,
    is above my patio, so a snowdrift of around 7 feet would be needed
    to block it!  And if that happens, the intake will probably be only
    one of my many problems!
    
    								-c
    
    p.s.  Since the through-the-window option must be made so it can
    be taken down in the summer, if we *did* get a snowdraft that high,
    I could just "unplug" the intake from the window and I'm no worse
    than what I have today with air loss.

    Sounds like you have it well figured out. Are you going to include
    screening to keep out creepy-crawlies. They may not bother you much
    but I bet they won't smell to good in your heating system. 
    	Other than that I like your idea. Sounds like you will have
    adequate draft...hmmm, could the draft become excessive? What are
    the wind patterns like around your home in the winter? Will there
    be any gusts blowing into you vent that could disrupt the burner?
    
    	Mark
    

    
    	Gusts?
    
    	Gusts???
    
    	Oh oh.  Frankly, I don't really know.  How would I test this
    short of building the whole contraption and seeing if it blows out
    my pilot light??
    
    							-c

    Well... I suppose you could rig up a damper of some kind if you
    really needed to but first...
    
    	Try to recall how the snow settles on you patio (beneath where
    your intake will be). Does your patio get swept clean during blizzards?
    If so it indicates high winds and gusts there. Does the patio face
    north, or north/east (I'm assuming you live in New England), if
    so worry about gusts, thats where you will see the worst storms
    coming from. When you open doors or windows on that side is ther
    much wind blowing into the house during storms?
    
    	Of course these "tests" are not perfect as the wind can blow
    in any direction, however I think you can rest easier if the answer
    is generally "no" to the above questions. In addition you should
    probably plan to extend you intake *through* the window so that
    you can add a downward scoop to it. In addition to keeping out the
    rain it should prevent an errant gust of wind from trying to turn
    your furnace into a ram jet.
    
    		Mark
    

    
    	Thanks, Mark.  The patio faces slightly north of north-west.
    One good sign, though, last winter I had to shovel the patio and
    there were no signs of significantly less snow than on the ground.
    Of course, the surface of the patio is around 3.5-4 feet below
    the ground level at the deepest point, so the snow can't easily
    blow sideways "off" the patio.  (Well, not until this winter now
    that the "front" of the patio has been terraced out so you don't
    feel like you're sitting in a hole. :-)  The level of snow cover was
    pretty consistant across the patio.
    
    	Good comment on the turned-down part of the pipe.  I'll have
    to remove the glass from the window or else make another box on
    the outside.  I'll take a look at it...
    
    							-c

    
    	P.S.  Yes, I'm in New England -- northern end of Nashua.

>    ... the entire assembly will be sheetmetal/ductwork just to
>    be sure.  I'm planning on attaching it to the furnace via sheetmetal
>    screws.  
    
    If your house is properly humidified (forced air heat with central
    humidifier, or room humidifiers), you will get a lot of condensation
    and dripping from the sheet metal ductwork. They make flexible,
    insulated pipe for this purpose.
    
    The code that I've seen for this (back in the cold midwest) stated that
    you can NOT attach it to the furnace. You must run it to the vicinity
    of the furnace's air intake.
    
    Some special furnaces are make to accept direct connection, but they
    are rare.
    

    
    Re: .10
    
    	Thanks.  I'm curious as to why the code would forbid attaching
    the air intake to the front of the furnace?  Making the outlet of
    the ductwork only in the "area" of the front of the furnace won't
    do me much good in cutting down the cold air coming into the house
    -- and may make it worse, although it would at least be concentrated
    in the basement.
    
    	Is the code problem with the "attachment" itself, i.e. an amateur
    like myself drilling holes around what should be a sealed cavity,
    or with the problem of potentially limiting the amount of air that
    can come into the intake?  Thanks for the code checkups!
    
    							-c

Let's suppose the air intake is attached to the furnace.
Let's also suppose that, to avoid gusts, the other end
of the intake is on the side of the house away from the wind.
	
Now, when the windo blows, it creates higher air pressure
on the side it blows against, and creates a slight vacuum
on the opposite side.  Does this mean that the air intake 
could have air sucked out of it instead?  Presumably that
would not be good for the furnace!  Is this a problem?

	Thanks,
	Larry

    
    	One more nail for the coffin...
    
    	I'm starting to think that this outside air-intake idea just
    might not work -- safely, that is.  One question, though -- what
    keeps a blast of outside air from coming down my chimney and blowing
    out my pilot light right now?  I have a plastic sheet in front of
    my fireplace and you should see it billow when the wind blows outside!
    
    	There might be a way around the anti-gust problem.  Since that
    scenario would involve air getting pushed down the chimney, wouldn't
    my chimney air shredder keep the pressure from building up and blowing
    out the pilot light?
    
    							-c

    Oh no... I think we've lost another topic...

    
>    	Thanks.  I'm curious as to why the code would forbid attaching
>    the air intake to the front of the furnace?  Making the outlet of
>    the ductwork only in the "area" of the front of the furnace won't
>    do me much good in cutting down the cold air coming into the house
>    -- and may make it worse, although it would at least be concentrated
>    in the basement.
 
    Put a 'plumber's trap' in the hose, so that the cold air at the bottom
    of the loop serves as a plug. The air will then only flow when the
    furnace starts up.
    
    I had this in Minnesota, and even at 45 below zero, or in blizzards (wind
    chill -80) the furnace room stayed warm.
    
    The house stayed warmer, since it eliminated all of the drafts in the
    house (the pressure differential was satisfied in the furnace room, not
    by every little pinhole in the house). It also stops the garage fumes
    from being drawn into the house when you open the connecting door.   
    

    
    	Plumbers trap in the airhose?  I thought a plumbers trap worked
    by holding water in the bottom of the loop so there couldn't be
    any air exchange (i.e. no sewer gas coming out of the sink).  I
    guess I don't understand why the cold air would form a sufficient
    plug to keep the cold air from coming out.  (I presume you're talking
    about just having the opening of the vent near the furnace and not
    coupled via an airtight box?)
    
    							-c

    
    	Just thought of something -- would a dryer vent covering the
    inside opening work?  It might be difficult to get it balanced "just
    right" so that the pressure differential would be enough to open
    it up, though.
    
    							-c

    Much of this has been said...
    
    Don't connect the vent to the furnace unless you know the
    furnace is designed for it.
    
    Do run the vent down so that it  outlets just above the floor
    - this reduces the chimney effect as does a "Trap".
    
    4" pipe is usually large enough - cold air is much denser
    than the hot flue gasses so the sizes  can be very different.
    4" meets the code requirements for most furnaces when they
    are in a confined space such as a furnace room. Codes don't
    require any vent in larger open areas such as basements.   
    
    - gerry

    
    Re: .18 and various others back there...
    
    >Do run the vent down so that it  outlets just above the floor
    >- this reduces the chimney effect as does a "Trap".
    
    	Please forgive me, but I'm still a bit confused as to what the
    pros/cons are of the various venting options.  Lets say I have the
    following cross section in the basement:
    
          ----------------------------------------------------- ceiling
    window
          +
          |
          |                             +------+
          |                             |      |
          |                             |air   |furnace
          |                              vents |
          |                             |      |
          |                             |      |
          +-------------------------------------------------  floor
                                         
    	Is this what is meant by a "trap?":
    
          ---------------------------------------------------- ceiling
    window =
          + \Vent           /-\
          |  \             /   \
          |   \  Trap     /     \        +------+
          |    \    |    /       \       |      |
          |     \   V   /         \      |air   |furnace
          |      \     /           \==    vents |
          |       \   /                  |      |
          |        \_/                   |      |
          +-------------------------------------------------  floor
    
    	I've probably exaggerated the scale of the trap, but do I have
    the right idea?  As I understand it, the purpose of this is to hold
    a plug of cold air in the "valley" so that very little excess cold
    air will come down the final slope towards the furnace.  (The siphoning
    would be trying to move denser air and so wouldn't work.)  Right?
    
	Is this what you were describing in .18?:
    
          ---------------------------------------------------- ceiling
    window =
          + \Vent              
          |  \                  
          |   \                          +------+
          |    \                         |      |
          |     \                        |air   |furnace
          |      \                        vents |
          |       \                      |      |
          |        \===================  |      |
          +-------------------------------------------------  floor
    
    	As I figure it, once the 4 inches of air immediately above the
    floor would get as cold as the outside air, there would be no more
    excess air infiltration through the vent, right?  As long as there
    wouldn't be much activity in the room to stir up the air currents,
    this probably would be as effective as the plug method.
    
    	If I have all this right, I'll have to go with the "plug" method
    since I'm in that room enough to stir up the air currents.  Thanks,
    everyone, for all the wonderful comments!  With my saved heating
    money, I'll raise a toast to the homework notesfile coming through
    again.
    
    							-c
                                                          

	...and then my thoughts were changed.

	A couple of evenings ago, I happened to be going up the basement stairs
when I heard the furnace burners turn on.  (I haven't added any air intakes
yet.)  Just to confirm the "worst", I put my hand near the bottom of the first
floor door (where I first noticed the huge draft going downstairs) and...
...not much of a draft at all.  ???

	Then the blower kicked on and the huge draft started that initiated this
whole discussions two weeks ago.

	Hmmm.  The timing didn't look right at all.  If the draft was caused
by the combustion air going up the chimney, it should have started as soon as
the burners turned on, not when the blowers turned on.  I investigated further,
and it seems that when they installed the cold-air-return ductwork, the work
was a bit sloppy and there are some openings (one big one around 1 square inch)
sort of hidden.  It seems to me now that the main reason for the draft under
the door leading to the basement is that a lot of the cold-air being returned
is coming through that hole instead of only through the cold air vents on the
first floor.  That would force a lot of air under the door to make up for the
lowered pressure in the basement.

	So, to get to my real question...  Is it ok to close up this hole (and
the smaller gaps in the seams) with just duct-tape?  Its only on the cold-air
side, so there shouldn't be any issue of heat-contact.  Thanks!

								-c

    If the hole in your cold air return is anywhere near the furnace
    itself, close it off! The fan will draw air down your furnace flue,
    putting poisonous products of combustion into your house.

    If the cold air returns are formed by sheets of metal nailed across
    two joists to form a duct then you will lots of places to try and
    seal and you'll never get them all. I don't think that a single 1
    square inch hole is causing your problem, it sounds like it is more
    than one in order to get a draft that you can feel and the door.
    
    Nick

	Yeah, I started sealing up the holes on Saturday and found lots of those
"ducts" created with the sheet metal spanning joists.  What a way to build
ductwork. :-(  There is enough air holes in both hot and cold air directions
that I'm suprised the upstairs gets any warm air at all!  (Well, ok, its not
quite that bad...)  Anyway, I've sealed like crazy on the cold air side (with
_much_ more to do!) and want to start tackling the hot air ducts.  Is there
any problems with using duct-tape on the hot-air side?  My concerns might be
totally unwarranted -- after all, it _is_ called duct-tape -- but I don't want
to accidentally tape too close to the furnace if there are any temperature
limits on the tape.

	Thanks!

								-c

    There is no problem using duct tape on the supply lines, that's
    exactly what it is made for.
    
    The reason for the sheeting of existing joists to form the return
    ducts is generally to increase headroom in the basement. It's usually
    difficult enough to find room for just the supply lines let alone
    the returns also. A lot more leeway is taken with the cold air returns.
    
    There is also a special duct caulking that comes in the standard
    tubes that you can use. It is specifically designed to handle the
    heat range. I doubt you can find it in any place but a heating/air
    conditioning/sheetmetal supply house. It is a red colored caulk.
    
    You can also use the gray rope caulk that is sold under the Mortite
    brand name. This also holds up very well. I'd stay away from silicone
    caulks unless you like distributing the odor that they emit while
    curing.
    
    I think what you have stumbled on is the difference between a quality
    duct system and a low cost system. You usually can't tell the
    difference unless you've worked on them for a while. But the quality
    of the joints is a key feature. If the joints are done correctly
    you shouldn't need any sealant.
    
    I worked my way through college in my father's sheet metal business.
    Thinking back the amount of ductwork I've fabricated and installed
    can probably be measured in miles. A conservative 100 ft/week is
    about a mile per year. I couldn't even guess how much
    my father has done in his 40 years in this trade.
    
    Nick

	Thanks, Nick!  Sounds like you sure have done a lot of ductwork and want
to do it right!  Where were you when the previous owners built my house??!!? :-)
Duct-taping here I come...

								-c

p.s.  By the way, Nick, I even found a place where a 6-inch elbow attaches to
a straight section and they were misaligned by 3/4s of an inch!  It took me
about 30 seconds to fix it...

re: .24
    
I can not compete with Nick's experience, but I have never had good luck
with duct tape on the hot air supply and I've bought "expensive" duct tape,
not the cheap stuff from Kmart. The stuff sticks fine for about two weeks
of heating, then it starts to curl. Maybe there is some sort of rating or
classification that Nick can share with us? 

In a related question, the duct tape I have also does not stick worth a
darn to the duct insulation (vinyl coated fiberglass), even though that's
what was recommended. Any suggestions on what to use to tape/glue the seams
on duct insulation? 

VCS

    I duct taped all my ducting 5 years ago and its still holding strong.
    Did you clean away the dust first mine had quite alot built up.
    
    -j
    

    I have been using an aluminum tape that is designed for installing
    fibreglass duct work (got it from MASI plumbing and heating in Milford
    NH) and it works great.  It's actually an adhesive coated aluminum
    foil and comes with a paper covering the  adhesive which you peel
    off before use.  Costs $10 a roll but well worth it.
    
    Tom
    

	Thanks for the suggestion, Tom.  I've put on some regular duct-tape
and it seems to get real soft and bubble up if the area gets too hot.  Perhaps
that tape at MASI would be better.  Where in Milford is this store?

								-c

Why does this NOTES file always cause me extra work?  8^)

This discussion got me wondering about the vent for my fireplace insert.
I knew the vent was there... cover looks just like the ones for the
bathroom vents, and the dryer vent.  But...I say to myself... knowing
the builder like I do, I wouldn't be at all surprised to find that 
he used *EXACTLY* the same vents... meaning it has a flap that opens
when air is blown out.

Of course, on the firsplace, I want the air to suck in... not blow out...
thus the flap would never open, and the fireplace would suck my heat up
the chimney.  Well, surprise of surprises!  For once, the builder did 
something right... the vent didn't have a flap, just a screen.

However...  THE VENT DOESN'T HAVE A FLAP!  (I know...I just said that...)
But that means the vent is always open...fire or not.  Hence the cold draft 
that I get when there is no fire.

So now, I'm trying to figure out a way to rig up a flap, or some other kind
of cover, that I can operate from inside the house.

Any ideas?

Bob

  Re: .30

  Why not put a plug or a flap on the fireplace end of the vent pipe?

  JP

Not sure where that is?  Its a fireplace insert, and I think the air for 
combustion comes in from a gap all the way along the base... (3 sides).

I think the only real place to work a valve is on the vent.  I can't get to the
tube that connects the vent to the firebix very easily.  I was thinking about
a couple of round plates with holes that line up at a certain orientation,
and close tightly at another orientation...kind of like the top of a grated
cheese jar or something.   I figure if I can get it to work smoothly enough,
I can put a little step motor on the assembly, and just push a button to
open, and push again to close.  If the holes are set up right, and symmetric,
I should be able to just keep stepping the motor from open to closed...

Then if I want to get fancy, I can get an IR emitter/detector set from 
Radio Shack, and set ot up to "look" through the holes, and provide a
signal to red and green LED's for some positive feedback regarding the
position of the plates... 8^)

Bob_who_needs_to_figure_out_how_to_keep_it_all_from_freezing_in_the_wrong
_position!  8-)

    I was away from my terminal for a few days so this response is for
    a couple of replies back.
    
    Yes duct tape sometimes comes loose, especially if there is any
    bit of dirt or oil on the metal. We never used just duct tape to
    secure round pipe connections like you'll see in some installations.
    The joints are first screwed together using self starting sheetmetal
    screws (drillscrews) and a 1/4" magnetic chuck in a variable speed
    drill or special screw gun. The duct tape is only used as a sealant.
    One trick with duct tape is to leave about 2" of tape hanging free
    when you start wrapping the connection and when you bring the tape
    all the way around the joint have the two ends meet glue to glue.
    Then continue with the tape a bit more to secure this tab down to
    the duct. It's very difficult to separate the ends this way.
    
    Duct tape does not work well in securing duct insulation. We used
    1 1/2" insulation with a nylon thread reinforced foil backing. There
    is a special nylon thread foil tape with peel off paper to expose
    the adhesive. This is the only thing that we've found to work and
    that is only on new, clean insulation. Once the insulation gets
    dusty in an attic it is very difficult to get anything to stick
    to it. We also used to use small thin metal disks about 1 1/2" in
    diameter to secure the insulation. I believe that roofers use a
    similiar disk to hold tar paper down. We'd punch holes through the
    centers of the disks and use screws through the disk and insulation
    into the metal duct to hold the insulation in place. Normally you
    didn't need to do this, but it is a reasonable fix if you have
    insulation falling off your ducts.
    
    I still get itchy remembering all the insulation we wrapped around air
    conditioning ducts in hot attics.

    Nick

Just what I've been looking for to seal the seams of some foil faced
rigid insulation.

How long are the rolls?

The only stuff I've been able to find is for sealing flue pipes and
would end up costing me as much as the insulation did!

Ken

    The insulation seam tape comes in rolls that are probably about
    100 ft in length. I've never really measured one and I didn't see
    the invoices from the supply house to know what it costs. All I
    remember is my father telling me to stop wasting it because it was
    expensive. I'd try a heating/airconditioning supply house if you
    were looking for some.
    
    Nick

Re .29: Where is Masi Plumbing?

	Clinton St. in Milford. (Near the oval... 1 way street running from
	South St. to Amherst St. Enters Amherst St. near the Fish Market.)

	Otterson St. in Nashua. (Same building as The Grainery restaurant.)

	I suspect you could find the aluminum tape at most bulding supply
	stores as well.

I'm installing a condensate pump for my condensing propane fha furnace.
It currently drains through a hole in the slab.

Should the line run outside (where it might freeze?) or into an inside 
drain (where the condensate might kill the happy microbes in my septic system?).

Thanks

bob

    I recently installed a furnace with some guidance from the heating
    contractor and his recommendation was to run it alongside the exhaust
    PVC pipe and through the outside wall next to exhaust vent.  The
    trick is to make sure the last foot inside the house slope downward
    to the outside such that no water (condensation) sits in a freezable
    location.  It's easily done by just taping the tube to the exhaust
    pipe 18" from the end, bending the condensation tube towards the
    ceiling, and then taping the tube just before in goes through the
    wall to the outside.  Works quite well.  The other suggestion he
    had was to soak the tube in warm water prior to taping it to the
    exhaust pipe.  It helped take the kinks out the tubing and allowed
    it to run much straighter along the PVC. 
    
    -Stan

    With regards to .3's comments on different nozzle sizes for oil
    burners there is a similar situation on a gas fired burner.  The
    nozzles (orafices) are different depending on whether you are burning
    street gas or propane.  In my case the burner came set for street
    gas but I had to modify it (replace nozzles) to handle propane.
    
    Also - in reply to the base note - I've done the majority of the
    installation myself, running all the ductwork, etc.  I did contract
    the heating contractor for about 6 hours one day to come and work
    with me on setting the furnace up and running the gas line (black
    iron pipe) from the furnace to the outside regulator.  He was excellent
    in guiding me in the furnace connections (electrical, exhaust, etc.)
    and offered many subtle hints along the way.
    
    -STan
    

    FHA furnace collect dust in the summer.  When you first start it
    up for the heating system, it burns off the dust/dirt which smells.
    This usually lasts for less than a week when all the dust/dirt is
    burned off.  
    
    So common is FHA in the south that the radio annoucers make jokes about
    the funny smell the first time it gets cold enough to start the heating
    plant for the season. 
    

    I seem to have a problem similar to .9. The fan won't shut off at
    all. Is replacing the fan limit control a DIY job? Where do you
    get parts?

I too have an old gas-FHA furnace. Last year, I had the gas company guy out 
to give it a checkup and he made a comment about pilotless ignitions that 
is relevant to the discussion here. I commented on all the "waste" of running a
pilot light throughout the summer and he said that it is better for the furnace
to keep it going. He explained that the pilot light keeps the system warm
enough to keep it dry. He felt that occasional condensation was the cause
of much rust and premature failure.  This makes sense to me. Perhaps someone
could verify his opinion.

-Steve Meier

    I'd heard the same thing also, but considering the size of the pilot
    flame, the size of the heat exchanger, and the distance between the
    two, I tend to doubt it.
    
    Maybe tho...
    
    Edd (who shuts the pilot down for summer)

Also, the pilot flame is a source of moisture...

-Mike

    In my case, with central AC, I also shut of the pilot to elminate heating
    any of the chamber containing cool air.
    
    Dave
    

    	I recently had a high eff. gas furnace installed in my
    newly aquired home. The problem is that there seems to be more 
    furnace noise (ie: air noise) following the installation as 
    compared to that of the electric furnace that was in previously.
    The fan speed is set to medium (can't go lower or will burn heat
    exchangers). The plenums and duct work in the house are straight,
    therefore less corners for noise. Because I work so closely with
    systems all day (literally) I have grown to dispise this type of
    noise, or to put it "IT DRIVES ME !@#$% GRAZY" ..oh... that's better.
    
    	Anyway, I would like to know if any of you readers out there
    who enjoy this kind of noise as much as I do, have any suggestions
    on curbing this noise. The installer (after I complained) mentioned
    that for a mere $350 he would install insulated plenums. Previous
    to the installation he guaranteed that it would be *very* quite.
    Huh!~
    
    	So, whats the work around? and dosen't this insulated duct work 
    (pressed fiber brd or what ever) created more dust? (wifes got real
    bad alergies).
                                                        
    THANX
    	gently going insane  GGI
    

    Where is the noise coming from?  Do you hear it at the furnace or is it
    an increased noise upstairs at the intakes/outputs.  If it's upstairs
    make sure all the grates are opened.  I believe a FHA system is
    balanced and if you close the dampers you can screw up the balance. 
    I have one intake in the kitchen that, when closed, noticeably
    increases the noise.
    
    	This is really stupid but last year I put a humidifier on the
    return plenum of my furnace.  The upstairs air noise got noticeably louder
    but I didn't question it - just chaulked it up to splitting the air
    flow to the humidifier.  This year I was getting the humidifier ready
    for the heating season and noticed that I never cut a hole in the
    return plenum for the humidifier.  The furnace was losing about a third of 
    the return air and it was making up for it by drawing more from the rooms.
    Once I cut the hole the furnace got real quiet!  Now you can hardly
    hear it upstairs.
    
    George

    If the problem is the sound of rushing air as heard through the grates,
    try "installing" fiberglas filters (make your own) behind the grates. 
    They will reduce the noise quite a bit without making much difference
    in the air flow.
    
    Dave

    	The noise seems to be mostly coming form he cold air returns.
    Most notibly form the large grate in the living room. 
    	What do you mean by "installing" fiberglas filters? Is this going
    to restrick air flow. Could you further explain this please.
    
    	This sounds sorta like the insulated plenum/ductwork idea the
    installer mentioned.
        What I would like to know is, "is this really worth $350?"
    Will I be a happy camper with a noticably quieter furnace or am
    I throwing away $350?
    
    confused...
    
    GGI
    

< Note 4056.3 by KDCFS1::LANGE "MADVAX - Beyond the thermal zone" >
You would probably loose. If the fan is running, there's bound to
be some noise from the blower, air moving through the filters and
the various other noise that the air ducts conduct and seeming
multiply; ie reverberation as the sound level bounces around
inside the duct.

A muffler system can be installed by looking at the frequencies
of the sound and setting tuned ports for the air system.
Insulating the air ducts does very little to reduce noise.

calvin hoe

BTW, I know what you mean; a hundred blower fans can be defening.

    Greetings
    
     Ok I've read all the other notes/conf on Gas/Oil/conversions from
     electric heat...none referenced the following:
    
     The local gas installers quoted me a price of $2800 for heat and $1800
     for central air..problem/question I have is they stated they would
     install the gas furnace in the ATTIC! (the AC goes outside). What
     happens when it's time for repair/tune-up...??
    
     Anybody out there have this kinda of setup? The unit is the super
     duper efficiency cost you nothing to run cheaper than any type blah
     blah...
    
     Thanks folks
     Canuck

Back in my early days working with an electrian, such a setup was
done in renovated condo's near the Bunker Hill Monument.  What ended up
happening for access was the entire ceiling in a square closet was
removeable to allow the unit to be installed, and removed if needed. 
The furnace was for forced hot water, not hot air.  The hot water tank,
20 gal's only, was also up there.

Brian

I've seen this in ranch houses in Austin.  There's no basement due to the
limestone ("soil" is too kind a word).  I observed horizontal FHA furnaces
in attic crawl spaces.  I'm not sure that it would be any worse than the
horizontal FHA furnaces that I have in my under-floor crawl space in my
current house.  As long as you can get to it to replace the filters, there
should be no problem.

    When I lived in Atlanta, I bought a brand-new, energy efficient, etc.
    house in about 1982.  It was a 2 story, colonial 'farm-house' (full
    front porch) with 
    
    	2 separate, gas FHA furnaces with air conditioning -
    
    one in the basement for the first floor and one in the attic for the
    second floor.
    
    There was the normal, pull down stair to the attic and I had no problem
    changing filters, normal maintenance, etc.
    
    The setup was GREAT!  Saved lots on both heating and air-conditioning
    with the capability to regulate each floor - both daytime activities
    and night-time sleeping.
    
    When I can afford it, I will add a unit in the attic of my house in NJ
    to take care of the second floor, not pump hot/cold air up from the
    basement (thru the 1950's non-insulated ducts in the non-insulated
    outside walls)!
    
    I would definitely go with it!
    
    	-Barry-
    

    Re .0
    
    I have to guess from your signature that you're from the Great White
    North.  Actually, gas furnace/ac units on upper floors and in attics
    are a very common practice in the southern and western U.S.
    
    pbm
    

    Ok Thanks folks for your reply. I guess I'm having a problem with the
    heat unit over my head rather than in the cellar.
    
    Yup from the great white north...Went to the University of Ft. Bliss
    Texas in El-Paso though and cant recall seeing "heat units" on the
    ceiling (Air/water conditioners on the roof of most dwellings).
    
    Thanks 
    Canuck
                                                               

	Could having a furnace in the attic in a cold/snowy climate
	cause problems such as condensation (on the underside of the
	roof) and ice dams on the eaves?  Supposedly, almost all
	attics have inadequate ventilation, but adding a furnace
	might make some things worse.

     RE: .6
    
      New type furnaces don't have any "waste heat" that would accumulate
    in the attic, due to thier high efficiencies.
    

    While the idea seems a good one, such as controling zones, making waste
    space to good use etc., I would think a lower unit would be better
    since the hot air doesn't have to be pumped downward since heat
    naturally rises;  by the same token an air conditioner in the attic
    would be a good idea, although attics in the summer are terribly hot
    so...  The conventional set up I think is easier to service.  
    Personally, I m more interested in engineered solutions (ie. heat
    pumps, etc)
    Frank

    re .8
    
    Heated air will rise when surrounded by cooler air, thus in a vent it
    wouldn't make any difference whether you were pumping the heated air up
    or down.

re .9:

>    Heated air will rise when surrounded by cooler air, thus in a vent it
>    wouldn't make any difference whether you were pumping the heated air up
>    or down.

Not correct.  Otherwise chimneys wouldn't work.

-Mike

    re. 10:  
    
    Close the flue and see how fast the smoke left in the chimney escapes.
    

      re: 11
      
      ...or close the vent and see how much good it does.
      
      --  sorry,  I  couldn't  resist.  Please insert the smiley face of
      you choice here:

    
    Below is a rough idea of an addition I'm contemplating. It's a 20x16
    family room with cathedral ceiling, connected to the existing house
    by a 6' extension to the den. Rough guesses at windows, sky lights and
    doors are shown by w's, s's  and d's.
    
    Heating is FHA, with existing registers in den shown by h(ot) and
    r(eturn). Foundation is 4' frost walls.
    
    I've talked to different contractors, and gotten different assessments
    on the amount and placement of heating registers in the addition.
    
    So if anyone out there has any ideas, or a similar project, I'd
    appreciate your insight.
    
                                        |
                               existing | new  *-dddd-----------*
                                    <== | ==>  |                |
                                               |                w
        *-   --------*------*-----------*------*                w
        |            |      |     h            |   sss          |
        |            | bath |                                   w
        |  kitchen   |      |    den                            w
        |            *-  ---*                                   |
        |                         r            |   sss          w
        |            * *    *-----------*--ww--*                w
        |            |-|                |      |                |
        |            |-|                |      |                |
        |  dining    |-|     living     |      *----wwwwwwww----*
        |            |-|                |
        |                               |
        |                               |
        *-------------   ---------------*

    Most common place for H(ot) registers to be placed is directly
    underneath a window.  I can only assume this is to help offset the cold
    being added to the room by the window.
    
    You have a lot of window space in the addition.  I would look at the
    direction of the prevailing cold winds.  I would also look at what
    would be the most typical furniture arragement patterns for this room. 
    I would put the register under the window that is most likely to get
    the cold prevailing wind and least likely to be blocked by furniture. 
    These may be at odds with each other.  I would fall back to heating the
    window as priority one and furniture as priorty two.
    
    You might put in two registars in places where you would normally only
    put one.  Like where you know a couch will most likely be.  Put a
    registar on either side of the designated couch area.  The furniture
    does not block the air flow but you still have heat on the wall with
    lots of windows!  You could run one duct to the middle of the addition
    and them split it off into several smaller ducts.  
    
    Don't forget to put a ceiling fan in this addition to run backwards
    during the winter to move the heat collected at the top of the vaulted
    ceiling back down to people level.

    
    Another consideration is; where are the existing registers? It may make
    your plumbing easier. How high is the ceiling?
    
    Rooms with high ceilings can soak up a LOT of heat. It's not the square
    foot area you're dealing with, it's the CUBIC feet of volume. Fans can
    help but are not a panacea, they create their own problems. If this is
    truly a cathedral ceiling, and fairly high, I wouldn't be surprised if
    you would need registers on at least two of the three walls, if not
    all.
    
    Re:-1
    
    A vaulted ceiling is one half of a cathedral ceiling, with a wall in
    the middle.
    
    CdH
    

    My furnace and ductwork are also not as quiet as I'd like. However, I'm 
    more interested in saving some oil (although I wouldn't mind killing two 
    birds). I'm entering this here because it's the only note I could find 
    that mentioned insulating plenums.
    
    I am going to insulate my ductwork this Fall (strictly for energy
    savings reasons) and it seemed to me that if you were going to insulate 
    the ductwork then you should insulate the plenum. Afterall, the plenum is 
    just the beginning of the ductwork. So, does this make sense; should the 
    plenum be insulated or are the possible savings relatively insignificant ? 
    Do they make an insulation to withstand the high temps or do you have to 
    buy an insulated plenum ?
    
    thanks

    
    I have an intermittent problem on a Borg-Warner FHA gas system. 
    Checked out all the basics - pilot flame adjustment etc.  Unfortunately
    I didn't inherit the manual with the boiler.
    
    Step by step:
    
      Thermostat closes, relay triggers & gas main valve (apparently) opens.
      I read the note regarding sticky valve pistons and I'm pretty certain
      that is not the problem.
    
      Boiler fires up, runs for a few seconds and then cuts out, never
      getting hot enough to trip the fan limiter (so the fan never starts)
      Setting the fan limiter all the way to the lowest temperature has
      no effect, the boiler never gets hot enough before it cuts out.
    
      When the valve cuts out, It *also* cuts off the pilot light and requires
      a 5-min wait before I can relight the pilot.  After a few cycles of
      this, the thing works fine.
    
    
    The pilot flame valve has a pair of wires going to a device mounted
    in the upper refractory chamber.  It's marked "Microtemp" & a model
    number and looks like a thermocouple.  I pulled this out, connected
    it to a multitester and applied heat up to about 190deg.  No effect.
    
    Can anyone confirm what this device is, and what it is supposed to do?
    Is it a one-shot or can it reset itself?
    
    Regards,
    
    Colin
    
    

    It sounds like a failsafe thermocouple to show that the burner has
    actually lit.  If it hasn't it is designed to turn off the entire
    gas supply.  (On the grounds that if the burner hasn't lit, there
    must be something wrong with the pilot light and that the pilot
    thermocouple may have failed too).
    
    Sounds like time to get out the repairman --- when it comes to the
    safety devices like this, even I, the inveterate I'll have a go at
    repairing anything type, prefer to leave it to someone who knows the
    device.
    
    Stuart

I don't think there's much safety risk in replacing a thermocouple (if that's
what you're dealing with).

Once when I was visiting my parents, the gas-fired water heater died.  They
called the gas company.  The gas company guy said that it was the thermocouple,
he couldn't fix it, but that it was simple job that I could do.  I picked up
a replacement at a hardware store, and installed it in about 10 minutes.

    
    .1 is right - I took no risk and called a repirman.  However,
    I was wrong about it being the source of the problem it was
    the main pilot thermocouple that had burned out due to a bad pilot.
    
    Thanks,
    
    Colin
    

  I've got a finnicky gas heater.  I can light the pilot light just fine, and
the burner will kick in and everything will work wonderfully.  Until the thermo-
stat tells the heater to shut off.  It shuts off both burner and pilot light.
I can then relight the pilot and start the whole thing all over again.

  I had the gas company come around to fix it (took two tries - I was not pleased
with them at all).  That fix lasted me the past heating season.  Now that I've
turned it back on again (relit the pilot), I'm getting the above behavior again.
The thermocouple looks pretty beat up, but I have no idea what a good thermo-
couple looks like.  That was one item replaced during the 'fix'.

  1. Does this behavior ring any bells for anybody?

  2. Does anybody know a good gas heater repair service in the Nashua area?

  3. Does anybody have any comments on conversion of a heater from pilot light
to spark ignition?

  For what it's worth, my water heater also runs from a pilot light and has had
no problems at all.

JB

    
    Wells & Son, Crown St nashua fixed a similar problem on my furnace
    for $50.  Included a new thermocouple and an adjustment to the
    pilot flame.  It has worked fine since.
    
    Only thing I know about conversions to spark ignition is that some
    programmable thermostats will not work with spark iginition, so check
    that when you convert.
    
    Regards,
    
    Colin
    

    Back to the basenote...I always heard it was not a good idea to shut
    the pilot down for the summer. Maybe it's do to the thermocoupler corrosion
    factor?
    I would do it myself if it wasn't for that rumor. Why pay the gas comp.
    anymore than we do. With no competition, they charge enough as it is.
         
    Dave'

    reply .0
    
    Not sure in N.H., but Boston Gas has option where you can pay then $30
    a year for a service contract.  The $30 covers all service costs.  Last
    year we bought a new gas furnace.  The electric pilot was not working
    properly.  The company we bought it from told us to have the gas
    company come out and fix it and send them the bill.  After three times,
    the manufacturer finally figured out what they had done wrong and were
    able to fix it.  Each of the three times the gas company came out, it
    was $25 as a base and more depending on how long they stayed.  This
    year we'll probably get the service contract.
    
    Rhonda

>    Back to the basenote...I always heard it was not a good idea to shut
>    the pilot down for the summer. Maybe it's do to the thermocoupler corrosion
>    factor?

  The thermocouple does look corroded and I did shut the pilot off for a couple
months this summer.  It was also shut down prior to my purchasing the place,
where I had problems immediately afterwards.  Perhaps that's the answer.

JB

re .7:

Slightly off the topic, but I've had a very bad experience with Boston Gas's
service people.  We bought a service contract, and ended up paying $125 to
an electrician to fix what Boston Gas broke.  They wouldn't admit that they
had been the ones who rewired our boiler controls incorrectly.  We just got
the renewal notice for the service contract, and I immediately tossed it.

    re .9
    
    I had execellent service from Boston Gas (once they finally arrived 23
    and 1/2 hours after the call).  They didnt touch the electrical part of
    the system.  My husband stayed with the service man while he was
    servicing the system because we were afraid he would break something he
    knew nothing about.  I can understand why you wouldnt renew with them
    and your misfortune will make us doublely careful if/when we have to
    call them again.  I think with Boston Gas, it's the luck of the draw as
    to which service man you get.  Some are excellent and others ....
    
    Rhonda

>I think with Boston Gas, it's the luck of the draw as
>to which service man you get.  Some are excellent and others ....

  No question.  I'd say that public service companies are like that.  I had the
same kind of experience with Energy North up here in Nashua.  As diagnosticians
these guys rated pretty low on the scale.  But one workman was well ahead of the
other in skill.

JB

Can you tell me where I can get insulating jackets for the ductwork?  I would
rather do this myself than pay a heating contractor.   I really would rather
not pay any more $ to they guys who did the shabby job on my house.

It looks simple enough.  Half my pipes are wrapped now -- don't ask why the 
other half isn't.


dana

I would also be interested.  I'm hooking up a wood furnace, and was thinking 
about wrapping the sheet-metal shroud in this.

								-- Chuck Newman

I wrote to the manufacturer of my gas furnace (Heat Controller, Inc.) about
hooking up duct work to provide combustion air for my furnace, and got some
interesting information (this worked so well for my wood furnace, I figured I'd
do it for my gas furnace too). 

From of the literature:
--------------------------------------------------------------------------------
WARNING:  ALL FURNACE INSTALLATIONS MUST COMPLY WITH THE NATIONAL FUEL GAS CODE 
AND LOCAL CODES TO PROVIDE ADEQUATE COMBUSTION AND VENTILATION AIR.

Combustion air requirements depend on whether the furnace is in an open, 
unconfined location or in a confined space such as a closet or small room.

FURNACES LOCATED IN AN UNCONFINED SPACE AND USING INDOOR AIR FOR COMBUSTION

An unconfined space must have at least 50 CUBIC FEET volume for each 1000 BTUH
of the TOTAL INPUT FOR ALL COMBUSTION APPLIANCES in the space.  The following 
table gives examples of the room sizes required for different inputs.  The room 
dimensions are based on an eight foot ceiling height

Example table for rooms with an 8' ceiling:

	BTUH		Min. sq. feet with	typical room size
	input		an 8' ceiling		with 8' ceiling

	 50,000			336		14'x24 or 18'x18'
	 75,000			469		15'x31 or 20'x24'
	100,000			625		20'x31 or 26'x30'
	125,000			833		23'x34 or 26'x30'
	150,000			938		25'x38 or 30'x31'

A confined space is any space housing a combustion appliance with dimensions 
smaller than those shown in the above table.  A confined space must have TWO
OPENINGS INTO THE SPACE.  ONE MUST BE WITHIN 12" OF THE CEILING AND THE OTHER
MUST BE WITHIN 12" OF THE FLOOR.  Size the openings based on how they connect to
the heated area or to the outside, and by the input of all combustion appliances
in the space. 

If the confined space is within a tightly constructed building, combustion air 
must be drawn from outdoors or from an area freely communicating with the 
outdoors.

USING INDOOR AIR FOR COMBUSTION

If combustion air comes from a heated area, EACH opening must have at least one
square inch of free area for each 1,000 BTUH of total input in the space.  In no
case should each opening have less than 100 square inches of free area.  Here
are examples of typical openings required. 

	BTUH		Free Area
	input		Each Opening

	 50,000		100 sq. inches
	100,000		100 sq. inches
	150,000		150 sq. inches

Caution:  Never take combustion air from a heated space containing a fireplace, 
exhaust fan, or other device that can cause a negative pressure.


USING OUTDOOR AIR FOR COMBUSTION

If combustion air comes from outdoors through VERTICAL DUCTS the opening and 
ducts must have at least one square inch of free area for each 4,000 BTUH of
total appliance input.  Here are some typical sizes.

	BTUH		Free Area		Round
	input		Each Opening		Pipe Size

	 50,000		12.50 sq. inches	4"
	 75,000		18.75 sq. inches	5"
	100,000		25.00 sq. inches	6"
	125,000		31.25 sq. inches	7"
	150,000		37.50 sq. inches	7"

Caution:  Never take combustion air from an attic space equipped with power 
ventilation if the ventilation system can be powered in the heating season.

If combustion air comes from outdoors through HORIZONTAL DUCTS, the opening and 
ducts must have at least one square inch of free area for each 2,000 BTUH of
total appliance input.  Here are some typical sizes.

	BTUH		Free Area		Round
	input		Each Opening		Pipe Size

	 50,000		25.00 sq. inches	6"
	 75,000		37.50 sq. inches	7"
	100,000		50.00 sq. inches	8"
	125,000		62.50 sq. inches	9"
	150,000		75.00 sq. inches	10"

If the furnace is in a location with an exhaust fan, there must be sufficient 
ventilation to prevent the exhaust fan from creating a negative pressure in the 
room.

Combustion air openings must NOT BE RESTRICTED in any manner.

CONSULT LOCAL CODES FOR SPECIAL REQUIREMENTS.

Air opening in the furnace casing front, return air grilles, and warm air 
registers must not be obstructed.
----------------------------------------
The literature shows illustrations for outdoor air using vertical and horizontal 
ducts.  The building is a single room with a water heater and a furnace, and an 
attic (with gable or soffit vents).

VERTICAL DUCTS:

This drawing shows a vertical duct (labeled inlet air) starting in the attic and
ending just above the floor next to the furnace, and a grate in the ceiling
(with a note:  outlet air in attic must be above insulation). 

HORIZONTAL DUCTS:

This drawing shows a horizontal duct (labeled inlet air) going out the side of
the house just above the floor, and another (labeled outlet air) just below the
ceiling. 
--------------------------------------------------------------------------------

This all left me with a couple of questions:

1)  Why two openings?  The only think I could think of would be for pressure 
differentials, but especially in the case where both ducts end in the attic I 
don't see how this would help.

2)  If a plenum was attached to the furnace covering all openings (except the 
exhaust, of course) to which both of these were attached, I would think that
should accommodate these conditions.  Any comments?  Probably want to insulate 
the ductwork and the plenum.

3)  If the ductwork contained both vertical and horizontal sections, (e.g., 
down from the attic then over to the furnace), I would think that their sizes 
could be treated separately (e.g., 6" duct coming down from the attic, then 8" 
duct going over to the furnace).

B.T.W., for the wood furnace I have a single 4" duct hooked up to the draft
blower, and I usually have that throttled way down.

								-- Chuck Newman

    
    
    I am thinking about converting house heating system from electric to
    gas. The house is colonial with electric radiators in each room. I have
    no problem with existing system, exept cost.
    
    One of the possible options is to convert 1st floor only to gas FHA. The
    thought is that it will cost less, gives most bang for the buck, and
    retaines some of the flexibility of electric on the second floor.
    
    The house 2nd floor is well insulated. The first floor has all the
    doors, vents ( range top, and dryer ), and half the basement is under
    the house garage. All of these add up to drafts and heat loses on
    the 1st floor. The second floor gets the radiant sun heat, and
    convectieve heating from first floor ( heat rises ). 
    
    All seems great in theory. Has anybody seen something like that done.  
    Could yo see any problems I am overlooking.
    
    Thanks in advance for any advice,
    
    Felix
    
    
    

This has been asked and answered numerous times.  Please
see note 1111.47 for a directory of relevant notes.

   Gary

    
    
    to .1
    
    I checked 1111.47 and 1111.51 before posting this note. I read thru
    notes and replies for 19, 802, 2466, and 1909. There is no postings
    I can find that has ONLY first floor converted to gas. If you aware 
    of such a note, please post a pointer.    
    
    

	I have a situation which parallels yours:


	I have a small cape (28 x 32) which has oil FHA for the first floor.
	It has old  windows and is not insulated (75 yrs old)

	The full upstairs was insulated and then finished but the owners put in
	electric baseboard heat (about 30 L.F. of it), and a separate thermostat
	on the 2nd floor for it.


	Basically we then have two zoned heat.


	1.  We would keep the upstairs cool (55) most of the day and night, and
		just turn it up when needed in the evening.  It was (and IS)
		expensive and that would limit our use.

	    Downstairs the oil heat would be kept about 65 or so.

	    About $1000/winter oil cost, plus electric bills in the cold months
		that could get to 80-90 bucks (normlly about 40-50)



	2.  Then we got a large wood stove for the basement (old Jotul 118 that
		takes 26" logs and used 4-6 cords of wood per season).

		We used it to heat the basement (previously unheated and down
		to 45 or so in winter) and the whole first floor, using oil
		only at the end of the night or in extreme cold or wind to help 
		the wood stove).  

		Total winter cost about  $1000/winter for both oil and wood.


		PLUS:  hardly ever ever ever turned on the electric heat
		upstairs.  Wood heat would permeate up from basement steps
		and whole first floor and got up into second floor - very
		noticeable difference.

	
		Final Plus:  Your  choice of heat source should the power go
		out or something happen to one unit or the other (like when
		oilfurnace started making noise Christmas Eve when it was 10
		degrees) -- just turn on the electric and wood.

		SO:
		
		depending on how open your stairs are and circulation, you may
		get some additional 2nd floor benefit from your first floor 
		oil heat.
	
		you get some flexibility in heat control of floors

		you get backup in case of failure (one way -- cant run a 
		FHA fan with no juice).

		Bob	

    Our house has oil FHW with two zones.  One for the basement, (which is
    never turned on) and one for the first floor.  There is no heat at all
    in the second floor.  The house is a high post cape with cathedral
    ceilings, so there's a lot of air space upstairs.  In the winter the
    second floor is always at least 5 degrees cooler than the first floor,
    but I kind of like it that way (though my wife would like heat in the
    bathroom).  
    
    Our last house had electric heat and wood stoves in the basement and
    living room.  We never turned on the electric heat except when we left
    for extended periods or had guests in the coolest upstairs room.  I
    second the experience of .-1 who found that running the woodstove in
    the basement help everywhere.
    
    Kind of like the apartment I lived in in college.  The crew above us
    paid about 1/3 of what we did for heat and kept the thermostat set
    higher!
    
    Ken

So, what's wrong w/ note 907?   ....Jeezis

re: .2

Note 722 is relevant, though it may not be obvious that
it is.  There are many others that are relevant one way
or another, and that are appropriate to continue.

In any event, please don't start new topics when existing
topics would suffice.  Alternatively, if you feel a need
to start a new topic, please try to use a title that 
emphasizes the distinction you're trying to make.  That
will always help  the next person down the line.  (Consider
that you researched four topic lines; the next person
now has at least five to look at.  We all need to help
keep things organized, or it will become totally impossible
to find things.)

   Gary

    
    reply .5
    
    I do not see why 907 is relevent. Did you read the note or just first
    line. 
    
    re .6 
    
    Thanks for pointer to note 722. It is not relevent to the question I
    asked, but informatieve anyway.  Your point about " Emphasizing
    distinction in the title " is well taken. Moderator please feel free
    to change title to more apropriate. ( I would try myself, if I can
    figure out how )
    
     
    I would like to thank everybody else who replied and send mail.
     
    
    Felix 
    

>                                              Moderator please feel free
>    to change title to more apropriate. ( I would try myself, if I can
>    figure out how )
    
Go to the base note and do SET NOTE/TITLE="new title"

    
>    I do not see why 907 is relevent. Did you read the note or just first
>    line. 


If I were a curious person, I'd read the note title and say to myself "now, 
there's a subject I should read if I'm interested in converting to one form 
of home heating vs. another"

Even if the discussion rambled within the base note, it's still easier to 
find the info than the current state of affairs where everyone feels their 
situation is unique.

Changing heating systems is changing heating systems  PERIOD.  It doesn't 
matter whether you have a 3 1/2 bath house and two dogs or a 2 1/2 bath 
house and a parakeet.

The title of 907 fits your problem

    
    Is any sort of maintenance recommended for a gas-fired, forced hot air
    burner? The Bryant unit I have is about 20 years old and I don't
    know if it's ever been serviced. Except for changing the air-intake
    filter each year, I haven't done anything to it in the six years
    I've owned it.
    
    Also, if I should have someone come in to service it, does anyone
    have a recommendation for a company in the Lowell, Mass. area?
    
    (I looked for an appropriate topic in the index, but found none
    that seemed to fit. If there is one, I'd appreciate a pointer.)
    
    Thanks,
    Craig
    

Do you have the manual for it?

Usually the only service needed for a gas-fired burner is to add oil to the
blower motor (there's usually a small tube you drop a few drops in) - use
motor oil.

				Steve

    re -.1, use motor oil for small electrical motors, not 10W-30
    automotive motor oil.

    10W30 automotive oil is what I meant.  It's what my Weil-McLain
    manual recommends as well as the company which installed it.
    
    					Steve

    re: .3
    
    They may recommend it, and it probably works, but it's NOT what
    should be used for bearings.  Engine oil is designed to emulsify
    water and hold it in suspension.  Oil for motor bearings should 
    precipitate water, so it drops out of suspension and doesn't 
    corrode the bearing.  There are a bunch of other differences 
    between engine oil and bearing oil too, but that's the major one.
    
    Now, in the bearings on your oil burner, it's probably only of
    theoretical interest because it's unlikely you'll get significant
    water in the oil, and the bearings aren't all that high-precision
    anyway.  But ideally, you should probably use something like a
    #20 non-detergent oil specifically formulated for electric motor
    bearings.  I suppose most people would never take the trouble to
    find it though, so Weil-McLain recommends something that will work
    and people will be likely to find.

    
    I was also wondering what maintenance was needed. It seems most
    heating companies have some annual checkup package available,
    and was wondering if it was really necessary. I guess a check
    of belts, if any, would be part of that. Isn't there also some
    check of the flame color to see how efficient the flame is 
    burning? Related, but maybe a different topic, aren't there
    some thermostat checks/adjustments that can be made? My 1914
    house has a BIG old gas/FHA furnace, that works great. I just
    want to keep it that way. Probably any company would want to
    sell me a newer model if they see it. Thanks.
    
    Peter
    

    The company which installed my system said no maintenance other than
    the oiling of the bearings was required.  I'm sure you could find
    someone willing to take your money.  Unlike an oil burner, a gas
    burner doesn't go out of adjustment.
    
    						Steve

    No owner's manual, Steve. Also, there doesn't seem to be any way
    to oil the blower without removing it. There's a tag on it that
    says "pre-lubricated," which I assume means it requires none.
    
    I can't believe there's something in this house that I don't
    have to spend money on. (I suspect I'm the main reason for
    Home Depot's rapid expansion.)
    

Well, it won't cost more than $50 or so to have someone out to look
at it and advise you.  If it makes you feel better, do it.

				Steve

    Try vacuuming (sp?) the burner area and the blower area.
    Oil the motor if required (I use light wieght machine oil)
    Check belt for tension and wear.
    Clean out bottom of chimney...black soot and dead birds...YUK !
    
    About every 3 years I take my blower right out and try to give it
    a real good cleaning. These squirrel cage blowers can trap a lot of
    dirt.
    
    Brian V
    

    There are several notes on gas furnaces, but since this one mentioned
    noise, I thought I'd ask here.
    
    When I bought my house almost two years ago, I was very pleased that it
    has a gas furnace.  When the building inspector checked out the house,
    he said that it was relatively new.
    
    I had always heard that gas heat is extremely quiet, but mine is not. 
    Not only is it loud as the heat is on (I haven't paid close attention
    to whether it's the cold air returns or the actual heat registers, but
    will tonight), once the heat goes off, there is a loud bang!  The
    blower stops, there is a pause, then a bang.  I am totally clueless
    about this stuff, so would appreciate help on what to look for.  Has
    anyone encountered this before?
    
    I can certainly call Energy North and have them come to service it, if
    necessary, but if there is something simple I can look for myself, I'd
    rather do that first!
    
    
    Susan

    
    My guess is that the BANG being heard is the a stretch of ductwork
    (probably the main trunk line) that is expanding and contracting.
    There are a number of things that can cause this such as:
    
     - It can be caused by a system that is too pressurized (the
       blower is set too high, or there aren't enough registers to effectively
       distribute the outgoing air.  
    
     - I've also seen one case where the cold air return was undersized and 
       the duct actually collapsed a bit whenever the furnace kicked in, 
       causing a bang.
    
     - Most common though, is due to simple contraction and expansion due
       to the heat. Most trunk lines have an "X" pressed into the sheet 
       metal to prevent noise due to expansion... but not always. 
    
    Start by tracking down the location where the bang is actally coming 
    from. 
    
    								- Mac

    I once had a bang after the unit turned off. Seems the squirrel cage
    fan blower was loose on its shaft. So, when the motor stopped, the cage
    kept turning a fraction of a turn until the set screw found a stopping
    point on the shaft. A quick turn of a screwdriver secured the set screw
    and the bang went away.

    The bang does sound like it's in the ductwork under my bedroom.  I'll
    try to be in the basement when it goes off.  Thanks for the
    suggestions.  I think I know what the problem may be, since you said
    that "not enough registers" could cause the problem.  The ducts to the
    bedrooms are pretty much closed off.  I'll try opening them to see if
    it alleviates the problem.  --S

    Well, I'm typing this in the cold...
    
    Early this morning, the entire house smelled "hot".  Not
    electric-wiring-hot, but hot-iron-on-clothes hot.
    
    Well, we crawled through the entire house and couldn't find the
    problem, although it did seem stronger near the heat registers!
    
    As the morning wore on, the house cooled down, and we noticed that the
    furnace wasn't kicking on...  Bad sign!
    
    This is in Seattle, so it could be worse, still, the lows are around 20
    right now, so it could be better.
    
    We finally got someone out this afternoon, who said that our 8-year-old
    Carrier unit had a "pretty much dead" blower motor (I can sometimes
    coerce it into running, I suspect sticky bearings.) and the "control
    circuit board" in the furnace is completely dead.
    
    Now, the estimate for repairs is $500 plus tax, but they immediately
    started pitching the idea of replacing it to the tune of $1300.  They
    said that there's lots more that could start going wrong, and that
    "they just don't last much over 10-15 years anymore".
    
    So, my questions: (finally!)
    1) Do these estimates seem at all reasonable?  In the ballpark?
    
    2) The statement that furnaces aren't expected to last much over 10
    	years really surprised me.  What is your experience with recent
    	FHA furnaces?
    
    Thanks,
    Kevin

    re: duration of FHA furnaces
    
    We have a Bryant unit that's 16 years old and it's still working
    fine.  There aren't many things that can go wrong with a FHA
    furnace - blower, burners, and heat exchanger.  The blower going
    bad is obvious, like you've experienced.  The burners don't
    really go bad - they can burn out or have the gas regulators
    go bad -b ut you usually start seeing problems visually before
    that goes.  The only real "invisible" problem that can occur
    is with the heat exchanger.  If one of these starts to burn
    out (get a hole in it), it can leak CO into the house, which
    can be dangerous.  We have a digital-readout CO detector in the
    house, and as of now it still reads 0 most all of the time.
    When we had our furnace serviced this past fall, they cleaned
    it all up and said that the only thing they couldn't verify was
    the solidness of the exchanger - and to keep an eye on the CO
    level as it was one of the early-warning-signs that the exchanger
    might be going south.
    
    I can't answer you as to whether $500 is valid for a blower
    replacement - but if it's $500 vs $1300, I'd be tempted to go
    for the whole new unit so you start from ground zero on the
    whole unit - plus you'll probably get a more efficient unit in
    the deal as well.  Up here in NH you can't mess around with
    nickel and diming a furnace - losing heat when it's -10 with
    a -40 wind chill factor ain't fun!
    
    andy
    

    One of the "improvements" which have been made to forced hot air
    furnaces over the past decade or so is to reduce the thickness
    of the heat exchanger to speed up initial heat transfer.  This
    has the side effect of reducing the useful life of the exchanger;
    the thinner metal is more susceptible to stress cracking.  I've
    heard numbers in the 15-year range for furnaces of recent vintage.
    
    If you're switching from a 80% efficiency unit to a 95%+ unit you
    might be able to justify the difference between a $500 repair and
    a $1300 replacement in reduced energy costs.

    I'd be *mad* if my furnace only lasted ten years!  My FHA gas unit is 25
    years old, and it's fine.  Well, it's burned out a few thermocouples in
    its time, but not recently.  (I suppose a newer one would be marginally
    more efficient, but since we only heat three rooms of the house in the
    winter, the heating bill is real small anyways, so the payback period
    would be longer than my lifetime.)  Bad enough that water heater tanks
    don't last - I've replaced two of those in fifteen years (the gas-fired
    one once and the solar preheat tank once).
    
    /Charlotte

    re:192
    
    	Sounds like it's time to start reading up on your furnace. You
    don't need to be an expert, but there are certain things that you
    probably should know.
    
    	In my case, I have forced hot water oil, but it also has a control
    module. The control module has a couple of leads labled B1 and B2. They
    are the neutral and hot wire feed to the ignition module, which starts
    the blower and lights the furnace when the boiler temperature goes below
    a certain point. Your system should be even simpler.
    
    	The point being that I can take a meter to B1 and B2 myself and
    help isolate down the possible cause of the problem, where you're at
    the mercy of the repair person. If they say something's bad, you have 
    to take their word for it, and if they're guessing and wrong, then they've
    already set you up by telling you to expect "other things" to go bad.
    
    	Without knowing your system, I can't say whether replacement is
    worth while or not. Your best bet at the moment would be to spend time
    with the repair person asking questions and learning as much as possible 
    about your system.
    
    	Ray

    Several years ago, I replaced a FHA furnace. The generic, contractor's
    unit that was installed was mfd by Magic Chef (the stove/oven people).
    The old heat exchanger went bad because the humidifier had been
    installed above the exch and condensation over the years corroded the
    metal until a hole started to grow.
    
    Lesson: the humidifier should be in the return side, not the feed side
    of the warm air.
    
    Several years later, we moved, so I don't know if that furnace is still
    there. Good luck.

most manufacturers of things that are sold as part of a house have
several lines of different quality.  most include a line of builder's
specials.  for an oil fired, hot water system, there are lots that
are over 50 years old.  in a new house, many fail in five to ten years.

a agree that more knowledge will be a big help.  get the model number
and find out where it sits on the quality scale.  the lower it is,
the more likely you should replace it.  ask a dealer.
if you can not find out, use the rest of the house and possibly the 
neighborhood as a guide.  if the dishwasher or stove has already
failed, or the plating has worn off the doorknobs, you should suspect
the furnace is also probably a builder special.  if you are in
a development, see what has failed for the neighbors.

there is lots of valuable info in this conference even if you are
not going to DIY.

get several estimates, and check references.  don't be surprised to
get one estimate that is double another.  check carefully what is
included.  one might propose using your old blower (that 
is going bad).  another might not remove the old unit,
or might add the charge to dispose of it at the local dump.

good luck.

Follow-up to .192:

Well, the more I got to thinking about the less it was adding up.

Furnaces have hi-temp cutoffs that are supposed to keep it from getting
hot enough to damage itself (or torch your house!).  Why should the control 
board go out at the same time as the blower?  And, if I could get the
blower to run, why was it called "dead"?

I went through the meager docs that I had for the furnace, looking for the
location of the "fusable links" that are supposed to be the primary failsafe
in the furnace.  I saw references to "manual-reset hi-temp cutoff switches"
that are only in some models (mine).  Sure enough, I went spelunking in the
guts of my furnace and found such a switch on the top of the blower unit
which had never been reset.  I pushed it, and closed up the furnace and
it immediately started up!  

Scratch one "dead control circuit board"

Now, the blower motor was definately struggling to spin up, and not always
making it.  Nonetheless, I cancelled my order for a new furnace, and warmed
the house up for the night.

In the morning a furnace technician (from a DIFFERENT place!!) came out
prepared to install a new blower motor, tore it down and informed me that,
"There's nothing wrong with this blower that a good cleaning and some oil
won't fix!".

Scratch one "dead main blower motor".

Morals of the Story:

*Maintain your equipment better than I did.

*Get a second opinion when somebody tells you that you need expensive work done.

*Get to know your own equipment so that incompetent/dishonest techs can't
   take advantage of you.

    re:199
    
    	Congrat's on your success. If the blower motor has brushes, the brushes
    can wear or you could get dust, or possibly oil in there that would cause 
    a poor contact with the commutator. I think this is what they look for
    when they look for "dead spots" on a motor. As with any motor with
    brushes, cleaning the commutator can sometimes be all that's needed. 
    
    	As you found, there are good techs and bad, and having a little
    knowledge can mean the difference between getting taken or not. It's 
    always nice to hear a success story.
    
    	Ray

    
    I think I wrote about this problem a couple of years ago, but I thought
    I'd try again since I haven't solved it.  4 years ago I had a new
    2-stage gas heater installed.  After it was installed, I noticed a
    musty odor in the house whenever the heat ran.  Knowing that the
    previous owners never had the ducts cleaned, I figured after 30 years,
    they could use it, so I had them cleaned.  The cleaning helped reduce
    the dust, but the house still has that musty/stuffy smell.  I change
    the filter regularly.  I've asked the gas company about it and they
    weren't any help.  My basement is dry - the dehumidifier doesn't run
    much at all until summer.
    
    So, I was wondering - is there a way to pull fresh air from outside and
    have it go through the heater?  I'm thinking that since I live alone,
    the house is closed up tight most of the time, so maybe it's just the
    recirculated air that gives off the musty smell?
    
    Does anyone know if there is someone I can call who specializes in
    problems like this?
    
    Thanks,
    
    - Cindy

If you have a forced hot air system, I should think it would be pretty easy to
make a small connection between your return air duct and the outside, if it is
not done already.  My system has one although it is not obvious.  The return air
ducts in the basement are really just the space between the floor joists, with
some sheet metal covering the bottoms of the joists.  In any case, this just
goes along up to an outside wall, and outside, you can see a little vent hole.

I wonder...you might check to see if you already have such a thing and look what
is around outside where the vent is.  Perhaps there is something musty/smelly
there.

Burns

        re -.1

    Hello Cindy...

    	There was a story last night on one of the news shows (20/20 or
    something like that) about a series of children becoming very sick (not
    to scare you...) in the Cleveland, Ohio area - turned out that most of
    these homes had forced hot air systems, and the furnace was taking the
    basement air only, as they had no cold air returns from the upstairs living 
    area. This was causing mold spores being sent through out the house. 

    	So you may want to check to see where your cold air is coming from
    to your furnace. 

    	As for pulling air from the outside, it could work, but to heat the
    outside air from -0 to 70, you will use a lot of gas...  First check
    your cold air returns.

    	Also, if you have a humidifier connected you may want to have that
    checked out. 


    	Good Luck,
    	Tom

    
    Hi Tom,
    
    Thanks for the info and the e-mail.  I will have the cold air returns
    checked out - that sounds like a definite possibility.  There was a
    humidifier on the old furnace, but it had been disconnected and it was
    removed when I had the new one installed.  I had hoped cleaning out the
    ducts would get rid of any moldy dust that was leftover from the
    humidifier.
    
    How much of a vacuum does as cold air return create?  I was wondering
    if I a piece of paper would stick to the return to show that it was
    working.
    
    Does it make more sense to call the gas company since they installed
    the furnace or an independent heating company?
    
    Thanks again,
    
    - Cindy

Yes, job #1 is to check the return path for your "used air."
Pulling air in from outside won't solve the problem, because you still need 
to get the used air out of the rooms to make way for new air.

High-tech tight-house systems use a heat exchanger to bring is fresh 
outside air and exhaust used air to outside, but use the exhaust air 
to pre-heat the incoming air, saving the heating that you've already paid for.

- tom] (the other one)

    
    ...plus FHA units can only impart a delta temperature to 
    the return air.  If you start pulling a lot of outside
    air, the return (inlet) temp. into the furnace drops and 
    you'll get a similar drop at the output.  I'd venture a 
    guess that a typical delta rise for an FHA unit to be
    30 degrees or so.

    The cold air returns are working in all the rooms.  When the furnace
    was running, I went to each return with a piece of paper and it stuck. 
    I put a strong air freshener in the basement and after a day, the smell
    is now throughout the house.  Not sure if it came up through the
    furnace or just through the door and floors.  I'll get a professional
    in soon to check it all out - thanks for the advice!
    
    - Cindy

    
    Ok, look for what is called a static relief damper in the return in the
    basement.  When a furnace is sucking air from the return sometimes it
    can't pull as much air as it needs thru the return and a static relief
    damper is inserted.  This is usually nothing more than a weighted 
    damper leaf in a round duct that is open to the basement.  It will
    appear closed or almost closed much of the time.  It is more often
    present in multi-zone air based systems because its nearly impossible
    to balance air flow when only one zone is calling for heat.  
    
    When the furnace is running and attempting to pull air from the return
    across the heat exchanger if it can't pull enough air a negative
    pressure is created in the return.  The static relief damper opens
    in response to this negative pressure and air from the basement
    is sucked into the return to reduce the negative return pressure. 
    Such a complicated explanation for such a simple mechanical device.
    Anyway, the damper can be adjusted with a small weight on the damper
    usually.  But the real question then becomes why isn't the return
    drawing enough air.  It might be a partially clogged return, a return
    may have been removed or reduced in size.  If you need the static
    relief damper, typically the only way of eliminating it is to add
    more return volume from the living space.  Also, in some systems
    this is a design feature in that the input thru the static releif
    damper permits the slow/eventual replacement of cold basement air
    so that the air down there doesn't completely stagnate.
    
    Just my opinions from what little experience I have with them in
    my parents house.
    
    Bud