Whole House Fans
#1
05-07-01, 01:23 PM
Poor me. I live in So Cal and I am willing to try anything to keep from paying $750 electricity bills again this summer. Our area gets cool at night, but may reach 100 in the afternoons. Someone suggested a "whole house fan." Theory being when it starts to cool off around 6pm open up the house, run fan, pulling in cool air, then close house when it cools way down.
You HVAC guys...that sound reasonable? This fan pulls the hot air out of the house and up into the attic, do I need some sort of support fan up there to blow it out again? Is it safe to assume that the "fan" will be more energy efficient than my 10 year old under powered air conditioner????
Thanks for the help.
mw
You HVAC guys...that sound reasonable? This fan pulls the hot air out of the house and up into the attic, do I need some sort of support fan up there to blow it out again? Is it safe to assume that the "fan" will be more energy efficient than my 10 year old under powered air conditioner????
Thanks for the help.
mw
#2
05-08-01, 02:52 PM
whole house fan
I just left one of these behind when I moved to a new home and I really miss it. I'm no pro on HVAC issues, but I prefer fresh air over A/C air whenever possible. Here are a few pros and cons:
PROS:
Instant results: Most of these fans are very powerful and they draw cool air into your home immediately.
Attic temp: Many homes are difficult to cool because the attic is so hot. Your home's attic will have fresh air circulated into it. It will take only a few minutes for the hot air to get pushed out, unlike passive systems that cool very slowly.
Easy installation: You have to cut a big hole in the ceiling, possibly header one ceiling joist if it's a big unit, and you'll need to wire one switch. That's it.
Fresh Air: There's nothing like cool evening air!
CONS:
Fresh Air: If it doesn't cool off at night, neither do you. Plus, I live in a fresh air place. If you don't, maybe you'd rather have yours filtered in the home instead of drawing in dusty or polluted air.
Noise: The more powerful the fan, the louder it is. If you can, place the fan in a stairwell or someplace not so close to bedrooms (and the TV!)
2 CAUTIONS:
You MUST have enough windows open to at least equal the size of the fan opening or you will create a vacuum in your house that might draw smoke and fumes down chimneys, such as your stovetop range hood or gas water heater. (I did this once--ick!)
Be sure you have large enough gable vents or other attic vents to handle the large volume of air you'll be kicking in their, or you'll pressurize your attic and make the fan even noisier due to turbulation.
Hope this helps. If you can usually count on cool evenings, I say "Go for it." I'm seriously considering putting one in my current home like I did in the other one.
HINT: put the wall switch way up high or even on the ceiling to avoid someone accidentally turning that sucker on in the dead of winter!
PROS:
Instant results: Most of these fans are very powerful and they draw cool air into your home immediately.
Attic temp: Many homes are difficult to cool because the attic is so hot. Your home's attic will have fresh air circulated into it. It will take only a few minutes for the hot air to get pushed out, unlike passive systems that cool very slowly.
Easy installation: You have to cut a big hole in the ceiling, possibly header one ceiling joist if it's a big unit, and you'll need to wire one switch. That's it.
Fresh Air: There's nothing like cool evening air!
CONS:
Fresh Air: If it doesn't cool off at night, neither do you. Plus, I live in a fresh air place. If you don't, maybe you'd rather have yours filtered in the home instead of drawing in dusty or polluted air.
Noise: The more powerful the fan, the louder it is. If you can, place the fan in a stairwell or someplace not so close to bedrooms (and the TV!)
2 CAUTIONS:
You MUST have enough windows open to at least equal the size of the fan opening or you will create a vacuum in your house that might draw smoke and fumes down chimneys, such as your stovetop range hood or gas water heater. (I did this once--ick!)
Be sure you have large enough gable vents or other attic vents to handle the large volume of air you'll be kicking in their, or you'll pressurize your attic and make the fan even noisier due to turbulation.
Hope this helps. If you can usually count on cool evenings, I say "Go for it." I'm seriously considering putting one in my current home like I did in the other one.
HINT: put the wall switch way up high or even on the ceiling to avoid someone accidentally turning that sucker on in the dead of winter!
#4
05-09-01, 09:40 AM
thanks
Great, thanks for the info. My electrician called me today and told me the fan uses about 1/8 the power the air conditioning does.....so this seems like a go.
Out area does cool off at night, yesterday it was 92, but last night got down to 64.....so just open the windows...turn on the fan, fraw that cool air in.
Out area does cool off at night, yesterday it was 92, but last night got down to 64.....so just open the windows...turn on the fan, fraw that cool air in.
#5
05-09-01, 10:53 AM
As long as you're in the attic...
Be sure you have enough ventilation to allow a large quantity of air to get out. Ideally, you should have the same square footage of vents as the fan opening. Not that you'll blow the roof off, but everything works better. Also, check occasionally to be sure the screens on those vents aren't getting plugged up with dust from your attic insulation, etc.
I know you lucky buggers down there don't get winters like we do up here, but if anyone else is "listening in" I recommend putting a large bag of insulation on top of the thing during winter months. just don't forget to take it off before turning on the fan again come Spring!
I know you lucky buggers down there don't get winters like we do up here, but if anyone else is "listening in" I recommend putting a large bag of insulation on top of the thing during winter months. just don't forget to take it off before turning on the fan again come Spring!
