Whole house exhaust fan size

[Cyngbaeld]

I'm wanting to get a large exhaust fan to cool the house down at night. I use some box fans now, but they aren't doing the job adequately. It'll have to go in a window with a cowling since I'm not into cutting holes in the walls right now. This is a 16x80 tin mansion. Anybody have an idea on how many CFM I need?

Is Dayton a good brand?

[Patt]

We had one put in our cottage it's a gable exhaust fan that is on a thermostat. It works great. Well worth the cost:

http://www.google.com/products/catal...CAcQ8wIwADgA#p

[Cyngbaeld]

Does it cool the whole house? How big is the cottage?

[Patt]

We are only 400 sq ft. It would definitely pull enough air for a bigger place, the big thing is to put it on the west end so it pulls in the cooler air from the east in the evening. And yes it does cool the whole house.

[Cyngbaeld]

Thanks!

[lamoncha lover]

Patt I have been looking for a fan....thought maybe get 2 for a 1995 sq ft attic area. You are well pleased with these?

[danielsumner]

My Ga house is 2300 sq ft. It has a full walk through attic and a galvlume metal roof. I installed two gable fans. Bought them from ACE hardware. They didn't cost very much. They came with a thermostat. I set them for 85 degrees. When the attic hits 85 the fans come on and exhaust to outside. Boy did it make a difference. You can walk around up there at mid day and not pass out. The electic/ac bill dropped like a rock. I'm sure you could set them up to exhaust the hot air from the living areas also. I think I payed like $60 each for the fans.

[Cyngbaeld]

How low can you set the thermostat?

[Mel-]

My parents lived with just an attic fan until the mid 90s in indiana which isn't as hot as texas but has a typical day of 90 with 90% humidity for july and august.

their's was in a hallway ceiling with no thermostat. had a wall switch and they just turned it on when it started cooling down at night.

later they put on a timer so it would come on and go off at a certain time but never a thermostat.

I always opened up a north window when I was growing up, that seemed the coolest air. and make sure my bed was right in front of it.

[Patt]

Originally Posted by Cyngbaeld

How low can you set the thermostat?

60 degrees Fahrenheit.

We like ours, our cottage actually has no ceiling so it is up in the top of the western peak of the roof. We turn it on and open the windows and it works just like our attic fan did in our old normal size house.

[Cyngbaeld]

60 should be low enough. Doesn't get that cool around here in summer. Thanks.

Sure miss being able to use a swamp cooler, but too humid here.

[SolarGary]

Hi,
This is a pretty good guide on whole house fans:
http://www.builditsolar.com/Projects...an%2026291.pdf

They reccomend that the fan cfm should be about half the volume of the house, so a 1000 sqft house with 8 ft ceilings would want a 4000 cfm fan. I think that's on the high side of what most people use.

We have one in our house, and its great -- I'd never have a house without one. Ours is two speed, and I highly recommend that.
Its also very important to have a way to seal it up for winter -- for ours, I built a 2inch thick rigid foam board box around it with the top that is removed for summer. I pile more insulation over the box for winter -- but then this is Montana

The guide above is also pretty good on how to mount the fan etc.

I've gathered together more stuff on whole house fans here:
http://www.builditsolar.com/Projects...htm#ActiveVent


Gary

[hippygirl]

Oh man! We had one in the hallway ceiling in our house when I was a kid and would turn it on as soon as the sun moved off the house. We'd then open the windows only about 4 - 6" and it would cool the house down very nicely.

I wish I could have one now, but I don't see any way to as I'm in a DW with vaulted ceilings.

[secretcreek]

We had a whole house exhaust fan in two different houses. Used them before we had AC..then later used them on days we didn't quite need AC. I just have to have moving air. Most hot weather is bearable ( today it's 85 with 89% humidity) if you can keep the air moving. We'd crack windows in bedrooms, or open the backdoor and allow the air to move thru the whole house, up the stairs and out the fan that pushed the air out and sucked the cooler air into the house.

This AC is so comforting and keeps the house from molding...but the drone and air noise disconnects me from the sounds of the outdoors, and I do not feel as alerted.

[Windy in Kansas]

You may need to get an application specific fan. I believe most fans described as whole-house attic fans designed ONLY to be mounted horizontally, i.e. which is generally through the ceiling. That horizontal requirement is based on the bearings used and how they accommodate the shaft.

I disagree with many posting and always recommend that a person get the largest belt driven fan (highest Cu. Ft. per minute) that they can. Not special order, but the largest normally carried in stock by a store.

[Texasdirtdigger]

We grew up with one in the center hallway of our house here in Texas. I almost always was reaching for cover before morning. It felt so good!!
When we build our next house....One is a definate must.
Ours was a big beast of a fan.... worked great. I can still hear those vent slats opening.

[ldc]

Cyngbaeld, I had one here in my first place. The only problem in the LA/E TX area is that it will bring the humidity with the cooler air! Eventually, it can rot walls out, etc. It was deff'ly cooler tho! ldc

[travlnusa]

One issue to keep in mind is the attic vents.

They must be large enough to let all of that air out, that you are pumping into the attic. Lots of places on the net will give you the figures, but without doing this step will greatly limit what the fan is there to do.