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-   -   Bathroom exhaust fans (http://www.diychatroom.com/f17/bathroom-exhaust-fans-32107/)

PirateKatz 11-18-2008 09:42 AM

Bathroom exhaust fans
 
Hi,

I just posted something very similar in the painting forum but I think it's more appropriate here.

My wife and I are interesting in installing an exhaust fan in our primary bathroom. Our house is about 100 years old and the bathroom was renovated in the 60's. We're trying to get a feel for how difficult/expensive it will be, or whether it something we should just hire a contractor for.

The bathroom is on the second floor and does have a centrally located light fixture in the ceiling, as well as lights built into the cabinet along the wall. So, it seems like it would be easy to get power to a new exhaust fan. It seems like it would be convenient to have a light/fan combo unit and control it both by a single (existing) switch, so we don't need to run any new wires. There's also a subpanel in the attic, as well as a electrical runs criss-crossing the attic for the bedrooms.

Our attic is unfinished but does have tongue-and-groove flooring, so a section would have to be removed to access the bathroom ceiling. Presumably, we could then run flexible duct work to the attic soffit.

All of these tasks *seem* to be within my level of ability but from experience, something unforeseen always crops up...

How difficult and expensive is a project like this?

hvaclover 11-18-2008 09:50 AM

You can buy light and exhaust fan combos. Vent thru the roof with ridged insulated pipe.

bradnailer 11-18-2008 10:14 AM

Had a similar issue so I just replaced the existing light with a light/fan combo using the existing outlet and switch and vented the fan to an outside wall. I wanted the fan on when the light was on so this arrangement was fine with me. You'll need to pop up some of the T&G flooring to have access to the light/fan so you can install the vent pipe.

PirateKatz 11-18-2008 10:42 AM

Thanks for the advice...

Though, it just occurred to me that there are a few issues I didn't think of before.

Even though the bathroom was remodeled, I'm about 90% sure the switch that controls the existing light fixture doesn't have a ground and there's the possibility that it still uses the original knob-and-tube wiring.

All of the wiring diagrams shown for the light/fan units I've seen, show 12/2 leading to a dual control switch, and 12/3 to the light fixture. Is it possible to simply use the existing switch and a single hot wire to run both the light and fan? Is the lack of a ground an issue? Can wire nuts be used to connect the K&T (if that's what's there) to a new fixture?

In terms of venting out of an attic soffit... We have aluminum siding, what is the most effective way to cut/drill through it?

Thanks!

bradnailer 11-18-2008 11:06 AM

As far as cutting the aluminum siding, you can use a jig saw with a bi-metal blade. If you cut it from the outside it will leave small burrs on the siding but since you will be putting a vent cap on the exhaust line, that won't be a problem.

If you can, you might consider snaking 12/3 from the switch to the light/fan, but it would be just fine to run the light and fan off the same hot wire from the switch.

Hopefully, some electrician types will adress grounding the new fixture.

hvaclover 11-18-2008 11:09 AM

Quote:

Originally Posted by bradnailer (Post 186785)
As far as cutting the aluminum siding, you can use a jig saw with a bi-metal blade. If you cut it from the outside it will leave small burrs on the siding but since you will be putting a vent cap on the exhaust line, that won't be a problem.

If you can, you might consider snaking 12/3 from the switch to the light/fan, but it would be just fine to run the light and fan off the same hot wire from the switch.

Hopefully, some electrician types will adress grounding the new fixture.

You can buy 4 1/4 hole saws that cut nice and clean.

pcampbell 11-18-2008 12:30 PM

I just finished this project. For me, it was difficult, but 99% of the difficulty was the fact that I was working in a 2 foot wide space where the rafters meet the floor, smashed behind the furnace in the attic.

I ended up venting horizontally but probably should have gone vertically. With a horizontal output, you need to worry about condensation build up. To try to combat this I insulated all of the duct work, grill housing, and the fan unit itself. Secondly, after the fact, I realized that I am spitting out this air, right to our patio, where our outdoor table and chairs are. While 99% of the time, this is not an issue, it could make for an embarrassing situation if we have company over, and are outside BBQing or something. Very unlikely, but a possibility. I am not yet comfortable with doing roof work so I figured I would go horizontal over vertical.

I like FanTech, these have fans which are NOT part of the grill housing. That is to say that in your bathroom, you just have a grill - in our case it is a grill and a light (PB100F). It makes the duct work slightly more involved, but results in less noisy, more powerful fans.

One note - FanTech bathroom fans do not take a ground, as they are completely enclosed in plastic. I went to go attach the ground and there is no where to hook it up. I went back to the manual and that is what it says.

Another thought - you probably want 2 switches - you do not necessarily want the fan on ALL THE TIME that the light is on. Or maybe you do... it may not matter to you, but it may matter. Just another thing to consider.

Circle hole saw bits work great... gotta love a nice clean hole.

hvaclover 11-18-2008 04:09 PM

Need to get more air changes to alleviate the trapped moisture. This is on of the best products for it


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