Conference 7.286::home_work

      Summerville Lumber has adapters that go from 3 1/4 X 10 to 4"
    round. I think this is what you'll need, as there are a wide assortment
    of pipes and vents available in 4" round.
    
    					Kenny

Mark,
	I think I have seen roof vents 3 1/4 by 10 at Summerville Lumber too.
Or it might be Spags.

	You can get 6" flexible duct there also. It is called
"FLEX-DUCT". The stuff is insulated so you whould avoid the sweating problem.

Re: .1
	 I can't say that I saw those 3 1/4 x 10 to 4" round at Summerville
Lumber. I won't think that they would make those either 3 1/4 x 10 is
32.5 cubic inches and 4" round is 12.56 cubic inches.
	6" round is 28.26 cubic inches.


	I hope this helps..

				Bill

    Total Air Supply in Nashua N.H., on east hollis street just before
    you go over the Hudson bridge.  They can fix you up with anything
    you like in the way of ducking or venting.

thanks for all the reies.  summerville had EXACTLY what I wanted.

-mark

Your welcome.  Just what did you get 4"?, 6"?, other?

Bill

I had to use the 6" for the volume.  3-1/4"X10 has a cross sectional area of
over 30 sq inches.  A 4" hose would only give me around 14 sq inches which the
6" gives me about 30. 

The only bummer is I had to by a hunck of 8' metal flexible hose for $11 and I
only need around a foot of it.  sigh...

Anyhow this weekend I can put in the fan, finish the sheetrock and call John
Mossey to do the skim coating.

-mark

    Earlier in the year, I installed a bathroom vent fan in the ceiling.
    It's vented through the vents at the edge of the roof. It's a typical
    Braun fan, with something like 20cfm exhaust rate. It only had a 3 inch
    exhaust outlet that I put an adapter on and made it 4 inches. I'm
    running about 6 feet of flexible hose, basically dryer vent hose, to
    the edge of the roof.
    
    The problem is, it really doesn't seem to have improved anything. The
    bathroom is small, probably something like 4X10. Steam buildup is still
    a problem. When I installed the fan, I repainted the ceiling. Now
    aprox. 4 months later, it's peeling. Even leaving the bathroom window
    open a few inches and the door open doesn't help that much. The steam
    line on the vanity mirror is still aprox. 2 feet down from the ceiling.
    The fan "is" drawing air but it just doesn't seem to be enough to keep
    up with the steam generated by the shower. The fan blade fins appear to
    be flat so I would assume rotation direction doesn't matter.
    
    Anyone have any suggestions as to something I may have done wrong
    during installation. DOES the fan direction make a difference. Any
    other ideas.
    
    
    Thanks
    Steve

First, you said 20cfm?  This is not nearly enough.

I just fixed a similar problem, so I'll tell you what I did.  The bath is about
8x8, including shower/tub unit.  There was an existing exhaust fan that wasn't
pulling the steam out.  The existing fan was a 110 cfm Nutone vented through
plastic flexible dryer vent hose out into the soffit, about a 4' run.  Note that
the end of the hose was just stuck into the soffit, left there to sort-of vent
out through the soffit vent.  This sounds like your setup.  This ceiling fan was
mounted somewhere around the middle of the ceiling, about 1-2 feet away from the
shower tub.

I installed another fan, a 130 cfm.  I used flexible metal vent hose (4" round),
and I kept the run to about 2' total: I placed the fan unit about 1-2' away from
the outside wall.  I also placed the fan unit directly over the shower curtain
rod, or slightly inside the shower tub area.  (Note that certain units are not
intended to be installed inside a shower area.)

I ran the metal hose to a wall vent cap (a standard aluminum dryer vent cap), so
that the exhaust was going directly to the outside through the soffit vent.  I
installed the vent cap so that it would vent down out of the bottom of the
soffit vent board.  Because I was hanging the vent cap in a vertical position
instead of the usual horizontal position, I sifted through the various vent caps
at Home Depot until I found one with a spring that was sufficiently strong to
close the damper up.  Then I attached screening across the outside opening of
the vent cap to keep the bugs out of it: this would be a concern should the
damper closing spring get tired in the future and not close the damper.  I also
didn't want to risk any corrosion between mismatched metals with this setup, so
I made sure that the hardware, screening and fasteners were all aluminum, the
same as the vent cap.

This setup works like a charm.  There is no steam at all in the bath, and there
are three women who love showers in this household.

The last point is air intake: you need to ensure that there is sufficient draft
for the exhaust unit to actually exhaust!  In the summer, make sure the window
is open.  In the winter, either open the window during showers or leave the bath
door ajar.

So, the important points are:

	1. short hose run
	2. placement on ceiling near steam-generation point
	3. venting directly to the outside
	4. sufficient cfm
	5. sufficient intake (draft)

-Chris

    on the box of a Broan fan 50 cfm is good food 45 sq. feet
    of floor space.  The smallest size I saw was a 50 cfm so
    -.2 could be very near the limit or way over depending on 
    his actual cfm.
    
       Dean

    I could be off on the size. I still have the box so I'll check when I
    get home. 50 cfm rings a bell. However if 50 cfm is good for about 45
    squares, then I'd need at least 2, or a much bigger one. This is just a
    wild guess, but I'd guess the shower is producing 2 rooms worth of
    steam a minute so one fan just can't keep up if this is the case. 2
    fans might.

    	Try opening the bathroom window from the top instead of the bottom. 
    This is not a fix, but something that might help until you get a bigger 
    fan installed.
    
    	Ray

	    Two feet, four feet or six feet, the difference in length wont 
	matter for runs as short as these.  The max flow will be limited
	by the smallest opening along the flow path.  A 4" hose connected 
	to a 3" fan would not limit flow unless it were somehow obstructed.
	    If the exhaust is just jammed into an eave, the installation 
	might obstruct air flow.  But even worse is the fact that lots of
	moisture would get pumped into your attic.  Too much moisture in
	an attic will reduce it's life expectancy.
	   
					Tim

A suggestion from this file a while back works wonders for us.  Step out of the
shower and run a cold shower for a minute or 2.  You can see it suck the fog
from the air.

How bad is venting into the attic if you have ridge and soffit vents?
I imagine it would still get some condensation, especially in the winter,
but I'd expect most of it to get wafted away eventually.

PeterT

    
    One thing that can happen in winter is that condensate can drip down
    onto the insulation, where it freezes. Over time a frozen puddle builds
    up.  When this eventually thaws it soaks into the insulation, which can
    take a long time to dry out. If you get enough water up there it may
    even find its way through the moisture barrier and damage a ceiling.
    
    I discovered after putting boards up in my attic that even the
    normal perc through the moisture barrier can cause condensation
    on the underside of the boards.
    
    Colin
    

    	Re:-2
    
    	What's the problem with putting in a hole ? Is it roof height or
    just that you think it will wind up leaking ?
    
    	If it's roof height that's a problem, and you have accessability to
    the eaves in your attic, you may be able to secure the output end of
    the hose to the soffit vent grate. This wouldn't be the best solution
    but it would be much better than blowing all the moisture up there day
    after day.
    
    	As was mentioned in the previous note, the steam will likely
    condensate on cold days and leak down on the insulation. It will be a slow 
    process, but one that will likely cause damage over time. Even worse, if 
    you happen to have a house with waferboard roof sheathing, your likely
    to see your roof start sagging between the rafters. Moisture seems to 
    affect this much more than plywood.
    
    	Ray

Venting into the attic is very bad.  But venting out a soffit vent is ok.

				Steve

No problem with the height.  More a combination of laziness and putting a 
hole through a layer that we just reroofed this past year and causing 
additional leaks.  I will probably go the duct to soffit vent route. 
So far I haven't noticed any problems, but its been in less than a year and
I suspect this is something that happens over a period of time.  Considering
the major leaks we had in the roof before we had it re-done, I'm not terribly
concerned with the steam from the showers causing much of a problem yet.
We've already had the puddles in the ceiling scenario to deal with.  But
it is something I will look at.  Does anyone make a fixture that goes from
a 4" round (attach to duct), and fans out into a wide thin opening that will
fit nicely in the soffit vent opening?

Thanks,
PeterT

>Does anyone make a fixture that goes from
>a 4" round (attach to duct), and fans out into a wide thin opening that will
>fit nicely in the soffit vent opening?

	    You might be able to get some sheetmetal ductwork that will 
	do the job for you.  HD or HQ would be a good bet.

					Tim

    
    This would be about the same shape as the reducer that goes from
    a round heating duct to a baseboard register for FHA.  The 4" duct will
    slip inside the 6" collar of the register outlet, and you can fill
    the gap with 2" foam gasket (used to seal around A/C units).  In the
    heating dept at HD.
    
    Colin
    

    Do you have one of them nifty water saver shower heads? The one I'm
    thinking bout is the small metal one that gives you a nice feeling
    shower along with MUCHO steam. I found this to be the case with the
    one I had, so I went out and bought a standard 2.5 gallon shower
    head from pollinex. sure the shower is not as nice but very little
    steam is produced.
    
    
    							./Dave