Ceiling Condensation - HVAC Advice Needed

[jamil]

Whatever you save during the few days of the year when the outside temp is too warm for heat and too cool for air conditioning, I think is more than being eaten up when you need to turn on one or the other.

If you leave it freely circulating what is the box for that you're building around it? I just think I wouldn't have a whole house attic fan unless I lived in a really mild climate. And then I'd want some mechanism that completely insulates it from conditioned air for when I do need heating or cooling.

I'm interested to hear what others say about that.

 

[steveh_131]

I think is more than being eaten up when you need to turn on one or the other.

This may be true.

If you leave it freely circulating what is the box for that you're building around it?

The box will essentially seal it off from below. So it will be sealed off from the house, but the fan and the interior of the box will still be open to the attic.

I may not be explaining this clearly at all.

 

[jamil]

One thing you might try if you have the resources, you could create a form fitting seal with spray foam. This might actually be a horrible idea, but I have to think it through here.

One place I worked years ago used expanding foam for shipping stuff. They put plastic around whatever we were shipping, put it in a box, then sprayed foam in. It created a form-fitting shell around the part. The same kind of concept could be used to make a form fitting foam piece to insulate your fan. You'd just press fit it over the fan when you're not using it.

But like I said, that may be a horrible idea. That foam spray isn't so good to breath and it offgasses for a long time.

 

[LtScott14]

The styro/ custom cover isn't too bad an idea. Is there a light in the hallway? Pull it out, anchor the box to a joice, add a ceiling fan w/ light kit. You know have air movement, and light, and your cover in place may help! I do agree about air movement, and have and use ceiling fans in all my rooms.
The whole house fan may seem antique, not really efficient. Some folks like them, my parents did the cover thing too. Some shade and cool nights we had to use covers because the outside was 50s and 60s.
Cost to run is additional. I have a hip roof on my ranch house, and am thinking of pulling a roof vent and put in a spinner type vent to help pull out some of the heat. An exhaust fan outdoors with an indoor thermostat maybe? Just thinking out loud.
Good luck. Am learning a lot from your posting!

 

[GodFearinGunTotin]

Alright guys, project of the week is to seal up that house fan. The assembly protruding from the ceiling is all metal, and is quite warm to the touch. I can feel gigantic amounts of heat coming in when I hold my hand up to it.

Here's my idea: Build a thin wooden box lined with foam board to seal directly to the ceiling all around the box fan.

I have some of this around:

I thought I might use that to keep it as air-tight as possible around where it makes contact with the ceiling and the wall.

Any expert opinions on this design? I have 4 very strong speaker magnets that I thought I might use to hold it to the fan.

The R-value on this foam board isn't huge. How big of a deal is that?

Thanks, guys.

Is this going to be temporary or permanent, Steve?

If temporary, I'd take some 2" or so styrofoam insulation board, cut it to shape and stick it to the metal housing with silicone. I'd take some of that caulk gap filler and fill the gaps between the walls and the styrofoam. Then fill any imperfections in the styrofoam cuts with caulk or some of that Great Stuff expanding sealer. It won't be pretty but it would insulate the temperature difference and be pretty cheap. Then when the weather cools off where you can work in the attic with out going into heat stroke, you can just tear it all out and throw it away.

If it's going to be permanent, I'd probably do the same thing...make sure it's going to help and not cause any other issues and then take some 1x stock and build a perimeter frame, on the sides of the fan enclosure and then cover it with luan plywood. Then caulk and paint it.

 

[steveh_131]

I'd like a cover that I can easily take on and off as the weather changes, ideally.

 

[GodFearinGunTotin]

There's any number of ways to fabricate a box, insulate it and attach it to the ceiling and/or fan. How about something "store-bought" like this?

http://www.amazon.com/M-D-Building-...217114&sr=8-2&keywords=whole+house+fan+covers

Here's kinda what I was talking about only this guy uses velcro...which would make removable.

http://www.instructables.com/id/Whole-House-Fan-Cover/

 

[looney2ns]

Be careful using foam that is left exposed indoors, it's flammable. It's suppose to have drywall or such over the top of it.

 

[steveh_131]

Well... it'll be exposed to the shutters below the house fan. Is that a real safety concern?