Conference 7.286::home_work

    I had a gas fired heater for a 20x40' inground pool.  This is 4 years
    ago and it cost roughly $130 initially to get it up to a comfortable
    temp. Then  I put a solar cover over it.  Now I would use a solar cover
    and not the heater....
    
    	Don
    

    Sorry, I don't have any experience to mention with "small"
    pools like yours.  
    
    I was the man in charge of a large in-ground, in-building
    pool at a local (non-profit, well-known institution), and
    can say that NO pool heats up quickly.... even with a
    massive heating system feeding the heater...
    
    Once it's up to (desired) temp., the problem is to KEEP it
    there.  I heartily suggest (recommend, urge) the use of a
    solar "blanket" (the big sheets of bubble wrap...) to do this.
    Even for an indoor pool, the savings in heat (and wear and tear
    on humidity controls) is impressive.  Outside, it also helps
    maintain pH, etc. levels.  Cutting down on "evaporation"
    doesn't just mean the water stays in....  your chlorine
    (however added) fades FAST in open air, too!!
    
    Hope this helps....
    
                                     - Ed -

    
    I've decided against a heater for now, unless I hear of some sort
    of solar heater. We have a Solar Blanket and will be opening the
    pool earlier than originally planned. We'll let the blanket sit
    on it for a month or so.
    
    Would still like too know if country and city pool temps would be
    different due to their surroundings?
    
    TN 

    I have an above ground pool that doesn't get sunlight till
    11 ish in the morning. I use a solar blanket and early in the season
    I use 150' of garden hose spread out on the driveway to absorb heat.
    I made fittings for the hose on the pump/filter and it runs water
    thru the hose slowly to get the most heat. It takes a while but
    I can bring the water temp. up enough to make it comfortable.
    This seems to be the cheapest way to heat a pool except for the
    power to run the pump.
    
    Jim

    I knew a guy who put a large spiral of 2" black plastic pipe on his
    roof (always in the sun) and hooked it up to the pump (as in .4).  
    He claimed that the water coming out of the pipe on a sunny day was
    over 100 degrees (I forget the exact number).
    
    It would eventually raise the temp of the pool significantly, but it
    also took a while.  The nice part is that it didn't use any fuel.

    How about a little more on pool heaters, such as...  
    
    How much does a heater cost?  Is it more-or-less just a boiler, like
    you use to heat a house with FHW? 
    
    How much fuel do they use (I'm thinking of a propane-fired heater)
    
    How much can you extend the pool season (in central Mass.) with
    a heater?

     A pool heater will cost anywhere from 1.5K to 3K NOT including
    installation. The exact cost will depend on the size and exact type
    of heater. (I don't even want to THINK of how much it would cost
    for installation!)  To run a pool heater will cost MUCH more per
    day than a house furnace. This is because the heater will run a
    much greater percentage of the time that it's needed. (ie, it will
    take DAYS of continuous running to get the pool from say 50-70 degrees.
    (water needs much more heat input to warm up than an equivalent
    amount of air) After the pool is up to temp the heater will have
    to come on a few times a day to maintain the temp, just like a house.
    You will HAVE to buy a cover of some sort, both to keep down the
    evaporation and the tremendous heat-loss that you get through the
    evaporation.
       As far as extending the season goes - there's no end to how far
    you can extend it with enough heat($$$) input! What you have to
    consider is how much you WANT to extend it.
       You may find (as I did) that buying and USING a solar cover will
    extend your season about 4 weeks (about 2 on each end) AND it pays
    for itself with reduced chemical usage and water evaporation!
    
    					Kenny

re .4:
>    I use 150' of garden hose spread out on the driveway to absorb heat.
>    I made fittings for the hose on the pump/filter and it runs water
>    thru the hose slowly to get the most heat. It takes a while but

maybe we could expand on this idea a little.  heating a pool by fuel is
expensive any way you look at it.  i was thinking of a 4x8 sheet of plywood
with two 4' circles of coiled black hose.  several questions arise: 1) how
to control pump flow through the solar heater only when the pool requires 
it.  i think some type of controller may be available. 2) how to prevent a 
meltdown when the sun is hot and the pool is too.  3) would a larger pump 
be required to overcome the added resistance.

i think this could extend the season if used with a cover.  with extra 
solar panels it could do wonders i'm sure.

craig

    
      A friend of mine put a coil of black poly(the semi-flexible stuff)
    pipe on his garage roof. This was plumbed into one of the pump
    discharge outlets with a Y fitting and a shutoff. When the pool
    was below the temp he wanted, he would have the valve open to the
    coil of black pipe. Whenever the pump was running it would send
    the water through that pipe picking up any heat that may be available
    from the sun. Once the pool is up to the desired temp., just close
    off the valve going to the black pipe
    	Most any pump will have NO problem pushing the water up at least
    10'. Once the water is flowing there will be NO extra strain on
    the pump because the water also flows back down.
    
    					Kenny

    
      RE. -1
    
      Is the Y fitting set up so that the water either goes stright to 
    the coil or straight to the filter, not both at the same time? Also
    where would the down line of coil go? If it comes back down into the 
    filter then it sounds like you'll need 2 Y fittings.
     

    
     Put the coil AFTER the filter (on the discharge side), the pump
    may not be able to handle the extra lift, but it will have NO problem
    PUSHING the water up the initial hill!  If you install the coil
    on the discharge side of the filter, you will need 2 Y fittings but
    only one shutoff.
    	 The heat coming through the plastic will remain
    constant, but the faster you can move the water through the pipe
    the better. -- Basic law of thermodynamics - The GREATER the difference
    in temp, the FASTER the heat transfer. That's why it costs more to heat
    your house when it's colder outside.
    
    					Kenny 

re: < Note 3085.11 by CSMET2::CHACE "let's go fishin'" >

>              but the faster you can move the water through the pipe
>    the better. 

    I'm confused by this.

    Here's the setup I've used for the past few years. I have a 100' coil
of 1�" black plastic pipe (4' diameter coil) which sits on my concrete
decking around my inground pool in direct sunlight. I have adapters on
both ends of the pipe to go to normal garden hose. One piece of hose goes
right into the pool (the discharge end). The other piece of hose is attached
to a submersible pump which sits on the steps in the pool water. Pump gets
plugged in, water flows through hose to black pipe in sunshine, out other end
and back into pool. Problem: submersible pump delivers about 35 gallons/minute
and exiting water temperature = entering water temperature. Solution: placed
a standard 3/4" valve in between the pump and the hose, crank down the valve
to regulate the flow to something slower, like 1 gallon/minute. Result: exiting
water is roughly 15 degrees warmer than entering water. This has the desired
result of putting heat into the pool, but what I've done is slowed the water
down to enable it to capture some of that heat. I open my pool in late April
and swim in 75 degree water by 1 week before Memorial day. Most of my neighbors
are barely getting their covers off.

-Jack

>    Here's the setup I've used for the past few years. I have a 100' coil
>of 1�" black plastic pipe (4' diameter coil) which sits on my concrete
sounds like one 4' diameter coil is enough.

>and swim in 75 degree water by 1 week before Memorial day. Most of my neighbors
what is considered warm?  is 75 in april too warm for july?  is one temp 
right all the time?  i never owned a pool before.

i am considering the following mix of complexity and simplicity.  a 4x8 
sheet of plywood with two 4' diameter coils of black garden hose.  garden 
hose to connect to the filter pump output.  at that point 2 tee's like 
this:      
                     
                          tee   valve    tee
                                 #1
    filter  pump    --------T------x-----T------   pool
                            |            |
                            x valve      |
                            |  #2        |
                            |            |
                             solar heater

by opening valve #2 and closing valve #1 i would get all flow thru the 
heater.  opening #1 some should allow slow enough flow thru the heater to 
pick up heat.  closing #2 would shut off heater.  covering the heater 
and/or leaving #2 open a crack should prevent meltdown.

i figured i'd just regulate by hand.  this sound reasonable?  one question, 
what kind of tee's, valves, and conversions from garden hose to pool hose 
should i look for?

craig

    RE: 12
    
       Sounds like a lot of junk around the pool just to get the temp
    at 75. How hot can you get it in the summer? What I'm looking for
    is in the mid 80's. Can you keep it in the mid 80's all summer? 
    
    TN

    RE: .14, boy are some people wimpy ;>)-75 Degrees..Brrrrr. I live in NH
    and still used my pool into the first week of October (until the water
    temp dropped below 66 degrees).
    
    Of course I put it in the middle of September and was going to get some
    use out of it last season by hook or by crook. (P.S. 66 is COLD!!!) 
    
    Eric (who used to scuba dive in RI just after the ice would melt)

re: < Note 3085.13 by TFH::DONNELLY "Take my advice- Don't listen to me" >

> >    Here's the setup I've used for the past few years. I have a 100' coil
> >of 1�" black plastic pipe (4' diameter coil) which sits on my concrete
> sounds like one 4' diameter coil is enough.

   I'm not sure what you mean, but maybe I wasn't clear enough. The pipe is
   in a 4' diameter coil but there's 100 lineal feet of pipe (like a laterally
   stretched slinky) so there's a lot of surface area to catch rays.

> >and swim in 75 degree water by 1 week before Memorial day. Most of my neighbors
> what is considered warm?  is 75 in april too warm for july?  is one temp 
> right all the time?  i never owned a pool before.

   I find 75 to be comfortable as long as the air temp is above 70. If the air
   temp is below 70 I'm not interested in swimming. 75 is probably not generally
   considered "warm" - I would guess that's somewhere around 80 or above.

   You're proposed setup looks good, but if you're anywhere near my latitude
   I don't think meltdown will be an issue for you.

   As far as the fittings go, Garden hose "almost" fits a standard 3/4" pipe
   thread. Since the hose uses washers and you won't be dealing with a
   closed system (i.e. not under pressure), 3/4" fittings shouldn't leak
   (mine don't). The pool fittings are standard 1�" or 1�" pipe thread. I'd
   get whatever fittings you can in plastic from a pool supply place - the
   remainder will need to be galvanized stuff which seems to be getting
   harder to find.

re: .14

   Where I'm located (Mt. Vernon, NH) 75-77 is the warmest my pool _EVER_ gets.
   I can't even begin to imagine what it would be like to be above 80.

   -Jack

   Oh, one other thing re: .13. You may want to consider the use of a separate
   submersible rather than the filtration system pump to push the water around.
   Like I said in .12, I believe you need to slow down the water enough to
   give it a chance to absorb some heat. That's going to backpressure your
   filtration system which can't be too good for it. (Also, this would
   eliminate the valves and tees.)

   My submersible is the best investment I ever made. In the late fall, winter
   and early spring it rids my basement of any water due to heavy rains. In
   the mid-spring it pumps the water (from rain-snow-ice) off my pool cover,
   and all summer long it circulates for my solar heater. Not bad for a $50
   purchase.

   -Jack

Well I've taken your information to heart and  decided to build a high quality solar
panel. My uncle has done what many of you have done with the hoses and things
and with his help $$$ I've designed and built a panel. I'll be installing it this week-
end. I will be taking temperature measurements every day to develop a standard
operating temp range and efficiency rating.  By word of mouth I already have some
others interested in one.  To anyone interested, I will keep you posted on my
success or failures. I used all high quality materials. Heavily insulated and has a
run of about 100 ft. It will be pumped with a sump pump for now and will look into
utilizing the pool pump later. The current size is 32" wide by almost 8 ft long.  I 
originally planned a 4' by 8' panel but found some old storm window glass to 
cut down on prototype costs. BTW, glass and copper pipe is expensive. Hope
it pays off.  Will mount it on the pool shed roof (south facing).

Ken

    Ken, your design sounds like something I'm considering, but could you
    adjust your screen width so that all of your text appears (I hate
    reading only part of a good reply)? Thanx.
    
    Eric

Well I've taken your information to heart and  decided to build a high quality 
solar panel. My uncle has done what many of you have done with the hoses
and things and with his help $$$ I've designed and built a panel. I'll be 
installing it this weekend. I will be taking temperature measurements every 
day to develop a standard operating temp range and efficiency rating.  By 
word of mouth I already have some others interested in one.  To anyone 
interested, I will keep you posted on my success or failures. I used all high 
quality materials. Heavily insulated and has a run of about 100 ft. It will be 
pumped with a sump pump for now and will look into utilizing the pool pump 
later. The current size is 32" wide by almost 8 ft long.  I originally planned a 
4' by 8' panel but found some old storm window glass to cut down on prototype 
costs. BTW, glass and copper pipe is expensive. Hope it pays off.  Will mount 
it on the pool shed roof (south facing).

Ken

    I'd also be interested in hearing about your experience in this area.
    In fact, do you have any more specific technical information? Piping
    layout and type, collector materials, insulation, etc?
    
    A point was made in .11 (and disparaged in .12), regarding flow in the
    collector. As .11 stated, a basic thermodynamic principle says that heat
    transfer is greatest when temperature gradient is greatest. This implies
    that to gather the most heat in the shortest time, you should pump
    as much water through the collector as possible. As .12 pointed out,
    this makes the discharge temperature cooler, but because there's so
    much more water discharged, the absolute amount of heat going into the
    pool should be greater, which means that the pool will rise to a
    comfortable temperature more quickly. This is not intuitive, but all
    other parameters being equal, it should be true.
    
    When most people think of such a collector, they think in terms of
    heating water to 120-140� for domestic consumption. While it's nice to
    heat that water as *quickly* as possible, the overriding goal is to
    heat it as *hot* as possible. Therefore, the water trickles slowly
    through the collector, getting close to the maximum collector
    temperature, but as it gets closer to that temperature the rate of heat
    flow into the water decreases drastically (given a 140� heat source, it
    takes much longer to raise the temp from 139 to 140 than from 79 to
    80).
    
    In the case of a pool heater, the design goal is to affect a quick
    temperature rise at a much lower heat range than the (assumed) maximum
    temperature of the source. This impliea that the water should be pumped
    through as quickly as possible to maintain the maximum temperature
    difference and thus the most efficient heat flow.

Hi Bill,

The piping layout is a serpentine of 3/4 " pipe. Input and output pipes
are 3/4 NPT for the initial use of the garden hose. A cedar frame
(quite nice looking) encloses the double pane glass, rigid insul.
and pipings. Of course the inside is painted black.

You are correct in that the ammount of calories (if I can recall from
college chem. is the amount of heat needed to raise one gallon of 
water one degree C. Since I intend on taking roughly 65-68 deg.
water and raising it to over 70, the ammount of heat required is
much less than taking 45 degree town water and raising it to the
temperatures you listed. I looked at a few pool solar heating
companies and they all focused on selling square footage as 
opposed to maximum effectiveness. In fact, the leading manuf.
pushes his low cost per panel, but it is a black molded plastic 
sheet that supposedly has a chemical in the plastic to raise its
solar absorbtion capabilities.  This is all fine and dandy but it
must loose a good 50% of its heat into the atmosphere. I am
more interested in capturing the most amount of heat, holding it
and transferring.

How does this sound to you?

Anyone have any opinions?

Ken

    
     You asked for opinions!!
    
      Your setup should definitely work! Also your (anybody's) pool
    pump should provide PLENTY of pressure to use it for pumping the
    water through the collector (providing the collector is on the output
    side of the pump). 
      Did you use 3/4" running in a serpentine fashion for the WHOLE
    collector? NO WONDER you said copper is expensive! You could have
    split the 3/4" into (2) 1/2" pipes, serpentined them in the collector,
    and then gone back into 3/4" for the return line. This probably
    would have cost less AND would have given more heat. (For two reasons-
    one is that only the water that contacts the pipe is heated. Smaller
    pipe has a greater percent of the water in contact with the surface.
    Second - you probably could have put a greater total length of pipe
    in the collector because of it's smaller size.)
    	Also be careful how hot the inside of the collector gets; It's
    possible for the inside of a collector to get hot enough to IGNITE
    or at least char, the wood! This won't usually happen when collector
    is in use (the cold water serves to cool the inside). It will happen
    when the collector is not in use but the sun is strong. Also make
    sure that when you put the pool away for the winter you leave some
    kind of opening in the piping (usually the pool outlets are plugged)
    in case of a pressure buildup. (when not in use the temp inside
    could go over the boiling point of the water).
     In any case it should work well, keep us pool owners informed of
    the results!
    
    	Kenny_who's_pool_temp_goes_up_3_degrees_per_day_with_the_solar_cover!

I agree with the pump pushing it through but need more info on pool 
pumps. The pressure these babys exert appear to move the water
quite quickly (which is against my principles). Someone also 
mentioned the back pressure created. Is their some way of reducing
the water volume and still get adequate filtration? I wouldn't want
the water to get dirty because its not cleaning quickly enough, not
would I like to damage the pump. Sure would appreciate help in this
area? My uncle owns the pool, I don't so I'm ignorant on pumps.

As far as the piping is concerned.  The problem with 1/2 inch is that
by reducing the diameter you are increasing the velocity. Also Its a
fine line between the surface area principle you mentioned. The 3/4
pipe does have more heating surface. Which would you go with -
Lower cost, more velocity, more footage, less heating area  OR higher
cost, less velocity, less footage, larger heating area. Tough decision
hugh? More pipe means more money too. I hope to have the 
opportunity to try other things like what you mentioned. Also, I 
concidered the genova plastic pipe. Perhaps, I'll be able to do a 
lower cost slightly less efficient model also (maybe not less efficient 
although on paper it should be). I know my next one will go with a single 
pane. Recent calculations show that I may not be gaining a whole lot 
by using pane and spending alot more money for it.

Good ideas, Thanx

Ken

    Would there be any corrosion problems with copper pipe because of the
    pool chemicals? The pH sould be OK, but I wonder what the chlorine
    would do to copper in the long run.
    
    Eric

re: < Note 3085.21 by ESCROW::KILGORE "Wild Bill" >

As the author of .12, thanks for the explanation as to why moving colder
water faster is better than moving hotter water slower - it seems to make
sense, but I guess it shows how much attention I was paying in Physics
class 20 years ago. It still seems intuitively obscure, though. Are you
really sure that that exiting water, running quickly, which has no
perceptible temperature difference from the pool water, is _REALLY_
going to add degrees to the pool? It would almost seem to me that pumping
30 GPM which is only .001 of a degree warmer than the pool is a waste of time.

BTW, I had no intention of disparaging the claim in .11 - sorry if it sounded
that way - I was only trying to present what, I think, works for me.

-Jack

    	A somewhat cheaper and LIGHTER frame for the solar panel collectors
    is the use of metal wall studs for the framing.  then you can just
    drill them and pop-rivet them together.  Works fine.  They take
    paint well to help extract all the heat and keep it within the panel
    better.  I helped my brother put the collectors on his roof for
    his house.  We were able to handle 8'X12' collector panels with
    2 people without much trouble at all.  (Minus the glass.)  Also,
    use high temperature insulation for the collectors.  Just a helpful
    hilt form experience.

    Any new experiences in the world of do it yourself solar heating for
    pools? I think I'll try something this year......once the ice melts!
    
    Terry

    My brother did the same thing with 1.5" polethylene black pipe ...
    put it in a coil backed by insulation and black shingles and covred
    with glass near Ottawa ... it really worked well until ...
    
    He went away one weekend and turned the pump off ...
    
    He developed a leak ...  Then he turned the flow through the thing
    off and it melted down!  Back to square one.
    
    He controlled the flow by a pair of valves, but found in general that
    flow through the heater was plenty without closing down the normal
    return jets at all (the output of the heater dumps straight into the
    pool.)  We noticed that with full flow through the heater on a
    partly cloudy day, the water being returned to the pool was cooler
    (heat loss in underground pipe runs etc), so we slowed the flow until
    the heater output temp was just above the pool temp and then on a
    sunny day it was noticeably hotter but that didn't matter.
    
    So, for this year we've got to find him some more cheap pipe!
    
    Stuart

    What do you mean it melted down?
    
    Any other new ideas out there?
    
    Terry

    The polyethylene pipes literally melted!
    
    It really got HOT inside the box !  Because the pipes ran in a coil,
    there was an open space in the centre.  If you put your hand on the
    collector on a sunny day, this centre section was uncomfortable to
    touch where the area over the running water pipes was cool.
    
    Now if we could only find pipe that was CHEAP and didn't melt there'd
    be no problem!
    
    Stuart

    My plan was to use ordinary black garden hose on the roof of my garage.
    Since the water temp will not likely get much higher than mid 80's,
    what effect if any will this have on the hose given that exterior of 
    the hose will be exposed to direct sunlight sitting on the black
    shingled roof. I don't plan to enclose it in any type of frame covered
    in glass or anything like that.
    
    Should I expect a meltdown if water is running through it continuously?
    What if I close the valve going into the hose?
    
    Terry
                               

    I wouldn't think what you describe, especially if you're going to run
    it all the time, it won't melt.  Most black hose is rubber, and that
    shouldn't be any problem.  The plastic hose is usually green.
    
    Just beware when you turn the pump off.  Having recently shingled a
    roof, I can tell you the shingles get too hot to touch with direct
    sunon them!  Rubber hose I wouldn't worry about, but plastic I'd
    be careful about.  You could do with a cover for when the pump is
    off.
    
    Stuart

    
    Just make sure that there is no water pressure in the hose when shut
    off. Pressure + heat = very short hose life.

    Opened the pool on Saturday. Connected the hoses to the system, and
    ran it up to the roof of the garage.
    
    Opening temp was 48F. On Monday it was 53F.
    
    So far so good.
    
    Terry

    Can you give us an update on the warming situation now?
    
    Bill
    

    I don't think enough water is passing through the hose quickly enough
    to make much difference. The pool temp has been 78 the last couple of
    days.
    
    Next step (probably next year) will be to put more line on the roof.
    And divert more water up to the roof. 
    
    Terry 

    The 1.5" pipe my brother was using brough his pool temp up to about
    80 - 82.  The hitch is that it went green again!  In spite of all kinds
    of care about pool chemistry this seems to keep happening.  I reckon
    his pool must get dumped on by tons of algae spores every now and then!

    "Temp UP TO about 80-82". I should have such problems here in Dallas,
    where my pool normally this time of year is almost 90 on its own!
    
    Eric

    re: .39
    
    yeah...a friend relo'd to Arizona last year from NH. She writes back
    once in a while and has mentioned that every so often, they have to buy
    a 250 lb block of ice and dump it into the pool to cool it down!
    
    

    Does anyone have any experience/knowledge/information about heating
    a pool using a heat exchanger ?    The system I am considering is
    a water-water exchanger that has two loops.   The heat comes from a
    closed-loop zone added to my gas heater (I have FHW house heat).
    The other loop is connected at the output of the pump/filter.
    
    Total cost for the system (installed) is about $1850.  This includes
    the zone (1" copper w/�" insulation, 20GPM circulator), the heat
    exchanger, thermostat, ,valves, etc.     The vendor claims that
    the exchanger is capable of delivering 55-80K BTU per hour.
    
    /Russ

    Have you considered solar heating for your pool?
    Littleton Pool in Littleton Mass sells a heating
    mat that you put on your roof through which
    water is circulated.

>    mat that you put on your roof through which water is circulated.

	    For a non permanent solar heater, you could use a couple of
	lengths of garden hose (preferably black) and a submersible pump.  
	You lay the hose out around the pool and pump the pool water
	through it when it's sunny out.  I'm not sure how much the pump
	would cost, but you could probably get the whole package for less
	than $100. 
	    A solar cover (a giant sheet of heavy duty bubble wrap) would
	help you maintain the water temperature and reduce evaporation.

					Tim	    
				

    In response to the previous messages, yes, I have considered alternate
    methods (some less expensive & some more).   The original question in
    reply .41 still remains:  Anyknowledge or experience on how water
    heat exchangers ?
    
    /Russ

    
    Go down to the plumbing supply house that your site uses
    with the make, model, serial # and BTU output (not input)
    and the same of your circulating pump.
    
    This info will allow them to find out how many gallons
    per minute your unit is engineered for - for a given 
    temperature rise.
    
    From that infomation, they can size up a heat-x and tell
    you how many gallons per minute of pool water has to go thru 
    it.  If you're planning on using the pool pump, then there is
    engineering data that comes with the heat-x that will tell you
    how many gallons per minute is flowing thru by reading the pressure
    difference of the inlet and outlet.
    
    :^)   I hope you have a big oil barrel...
    
    Keep in mind that, it takes one BTU of heat to raise one lb. of
    water one degree F.  One gallon of water is approx 8 lbs.
    
    Hope that helps a little.
    
    Fred

    
    The first paragraph is relating to the furnace data.