Thoughts on attic fans? (how much, house, vs.)

[kryptos]

Thinking a little ahead here...
We have a fairly open multi-level home with AC, which we leave turned off unless we have sweltering hot days (90-100 F) in the summer. Our basement is finished, and since it is a lot cooler, DH & I move down there for summer

A friend mentioned installing an attic fan to cool down the house and we're wondering about how effective it will be. Any thoughts on this? It is supposed to work well for Colorado, but I don't know of anyone who has these installed. How much of an improvement would we see?

[tfox]

Originally Posted by kryptos

A friend mentioned installing an attic fan to cool down the house and we're wondering about how effective it will be. Any thoughts on this? It is supposed to work well for Colorado, but I don't know of anyone who has these installed. How much of an improvement would we see?

An attic fan is a good idea. Basically, it's very simple -- the idea is that it blows hot air out of your attic on hot days and blows in the (relatively cooler) outside air, resulting in improved energy efficiency. It works pretty much automatically with a temperature sensor both in and outside. It's also quite cheap. I wouldn't expect a dramatic change, but it's kind of like adding insulation -- every little bit helps and this would be well worth the energy savings.

[steveindenver]

We had one at our old place. It worked very well at night -- which makes sense when you consider it often drops into the low 60's and 50s for most of the summer at night. Last year we ran the A/C for maybe a couple of weeks total.

It will be harder to run one in our new place because the insulation is blown. I suppose I will have to get up there and cover the insulation with plastic before we start blowing air around in volume.

[Katiana]

They are noisy. Our house is older, so we went down to Home Depot to look at new ones and were told they are still noisy. I call ours "the train". If I had been the original owner of this house, I would have put in a swamp cooler.

[Charles]

Originally Posted by Katiana

They are noisy. Our house is older, so we went down to Home Depot to look at new ones and were told they are still noisy. I call ours "the train". If I had been the original owner of this house, I would have put in a swamp cooler.

Are you sure this is an attic fan and not a whole house fan? I think attic fans are pretty quite. The attic fan moves air from the attic to the outside and the whole house fan moves air from the house into the attic.

I installed a whole house fan in California and it was very loud - which made using it a nuisance because I liked to use it first thing in the morning to get the coolest air in the house.

[Katiana]

I thought they were one and the same. In any event, we don't use ours much, b/c it really does sound like a train.

[denverian]

I think two different types of fans are being discussed here. One is normall installed in an attic vent area, set to operate when the temperature in the attic gets to a certain temperature, and it simply sucks hot air out of the attic. Those types of fans you wouldn't hear in your house. They other type, which I refer to as an "attic fan", is large and normally built into the ceiling somewhere in your house (ours is upstairs over the hallway where the bedrooms are located) and you open windows throughout the house, then turn it on, and it quickly sucks in cool night air and cools the entire house very well. I think these are great for Colorado in the summer because the air is cool and dry enough to make for very comfortable sleeping and much cheaper than running the A/C all night.

[kryptos]

So, would there be a significant difference in the performance of the two (Whole house fan Vs. Attic-only fan)? I'm inclined to try just the attic fan out this summer to see how well it will work.

[Charles]

Originally Posted by denverian

They other type, which I refer to as an "attic fan", is large and normally built into the ceiling somewhere in your house (ours is upstairs over the hallway where the bedrooms are located) and you open windows throughout the house, then turn it on, and it quickly sucks in cool night air and cools the entire house very well. I think these are great for Colorado in the summer because the air is cool and dry enough to make for very comfortable sleeping and much cheaper than running the A/C all night.

This is a whole house fan. It is totally different from an attic fan which moves air from the attic to the outside.

[Charles]

Originally Posted by kryptos

So, would there be a significant difference in the performance of the two (Whole house fan Vs. Attic-only fan)? I'm inclined to try just the attic fan out this summer to see how well it will work.

An attic fan is autonomous. You install it and it works as needed.

A whole house fan works XOR with an air conditioner. Either you use AC or you you use a WHF but not both.

WHF are noisy and have the biggest impact when the air outside is cooler than inside (like at the end of the day if hot air has been trapped in your house....or early in the morning when you want to pre cool your house so your AC doesn't have to work as hard later.)

WHF can create a slight wind chill effect but the best tools are ceiling fans. The wind chill effect they provide is probably like 5F to 10F.