Would an attic fan help cool my house?

[ZmOz]

I've got a 2000 sq. ft. 2 story house, and no air conditioning. There is also no shade on any side of the house. It has a relatively steep roof, so the attic holds quite alot of hot air. I was thinking about installing an electric fan that would exhaust the attic air to the outside. Would that make a noticeable difference in the temperature inside the house? It's usually not that bad in the middle of the day, but at night it really sucks. We've allways got so many fans going it sounds like a 747 is trying to take off.

 

[Drowned Rat]

Re: Would an attic fan help cool my house?

Is your attic vented at all? I've seen alot of houses here in Arizona that install fans under the eaves. They pull air into the attic and push it out the vents in the roof. Alot of houses here also use ceramic tile roofing to prevent heat buildup, or they will use a lighter colored shingle. To answer you question though, yes. It should help a little. Maybe 2 or 3 degrees, which may be enough in your neck of the woods. Down here in the Summer, we get second jobs to pay the electric bill.

 

[LubeDude]

Re: Would an attic fan help cool my house?

Yes, it will help more than 2-3 degrees, but probably only in the upper story. You have to make sure you have vents in the eaves so you can suck in as much as you blow out. If you turn it on about noon, and dont let it get that hot, it will do a better job than if you allow the thermostat that comes on them to turn it on automatically. Also you have to make sure you have the floor in the attic well insulated. Also in the evening it would help to put a very large fan in an upstairs window blowing out and opening the windows downstairs so it can pull the cool evening air in. Another attic fan fashioned to the window works pretty well, even two. You need to get the hot air out so the cooler air can come in.

 

[18rabbit]

Re: Would an attic fan help cool my house?

OmOz – on average, 10-12 deg F drop in temp inside the house just by adding a fan in the attic. The fan should pull/push across the longest part of the house…in one side and out the other. Almost as good is a turbine vent…those ball-looking sheet metal wheely-bob thingys that spin when the wind blows. Advantage of the turbine is no electrical.

 

[John Carpenter]

Re: Would an attic fan help cool my house?

I've used them and they make a tremendous difference. Just remember that you can pull air as far as you want to, but you can't push it at all. In my opinion, an attic fan will do a much better job than the roof turbine jobs.

 

[ZmOz]

Re: Would an attic fan help cool my house?

Wow...I didn't think it would make that much of a difference. There aren't any vents except small ones in the eaves. And yeah, there's a fan in pretty much every window.

 

[Boomyal]

Re: Would an attic fan help cool my house?

ZmOz, go to Home Creepo and look at their fan selection. They have both thermostatically controlled gable fans and those mushroom domed roof fans. They will say on the box how many square feet they are good for and they will tell you how many square inches of intake ventilation you will need to use each size.<br /><br />On a 90 degree day, the temperature in your attic is probably 140-150 degrees. If you can get your attic closer to ambient outside temperature it should have a significant affect on the temperature in the house, even with good insulation.

 

[ZmOz]

Re: Would an attic fan help cool my house?

Geez...150? While I'm up there I think I'm going to run a couple hundred feet of pipe and pump water through it as a pool heater.

 

[Boomyal]

Re: Would an attic fan help cool my house?

Originally posted by ZmOz:<br />Geez...150? While I'm up there I think I'm going to run a couple hundred feet of pipe and pump water through it as a pool heater.

Depends on the color of your roof. <br /><br />People actually coil black pipe on dark roofs and do just that.

 

[ZmOz]

Re: Would an attic fan help cool my house?

My roof is black. Never really thought about it before, but why are so many roofs a dark color? Doesn't make much sense when you think about it...

 

[Boomyal]

Re: Would an attic fan help cool my house?

Originally posted by ZmOz:<br />My roof is black. Never really thought about it before, but why are so many roofs a dark color? Doesn't make much sense when you think about it...

Very true, re most roofs. Black/dark composition roofs actually self destruct due to the heat they absorb. Plus without a doubt, they make you turn on the airconditioning sooner than you would otherwise have to. In some circumstances it might make a difference as to whether you use the A/C at all.<br /><br />If a hot attic can make a 10 deg difference in the temperature inside it might go from 85 down to 75 in the house if your attic was cooler either from a reflective roof or good attic ventilation.<br /><br />I have two 40 ft storage containers. They are white. You can go inside them in the summer and they are not uncomfortable. Go inside one of those red oxide colored containers on a 90 deg day. You think you walked into a sauna.

 

[SS MAYFLOAT]

Re: Would an attic fan help cool my house?

Have you thought about a ridge vent? It is a vent that runs the whole length of the peak of your roof. It then gets capped with matching shingles that is on your house. Not very noticiable at all.<br /><br />The normal convection of air currents will keep your attic air moving. No electric to run, no need to remember to turn it on/off, and no big vent on your house. Also putting in some small soffett vents will help increase you draft to get the hot air out.<br /><br />Houses around here that get reroofed usually get the ridge vents installed plus new construction houses get them also. I put them on my old house and it made a very big difference in keeping the house cooler. I like them because there is very minimal maintenance if any at all. <br /><br />Just another alternative to attic fans to think about......

 

[18rabbit]

Re: Would an attic fan help cool my house?

Have you thought about a ridge vent?

It’s kind of a trade off … you want the vents when it is warm outside but not when it’s cold or it increases the home’s heating cost. You do want some air circulation at all times to prevent mold.

 

[craneman72]

Re: Would an attic fan help cool my house?

i have a ranch house and installed an electric thermostat controlled fan, made a world of difference, i keep mine set on 80degrees, when the temp hits 80 in the attic, the fan kicks on, before installing, i had 3 window unit air conditioners , i am now down to one unit 8k btu, house stays very cool<br /><br />just my opinion

 

[Mike Langianese]

Re: Would an attic fan help cool my house?

Go with the ridge vents that Mayfloat recommended and Add extra insulation in the attic. Home Depot will “lend” you the blower if you buy several bags of the fiber insulation.<br />Just another way to go...

 

[Xcusme]

Re: Would an attic fan help cool my house?

Just a basic concept to ponder. Heat doesn't rise....heated air rises. Heat travels in every direction. A super heated attic will radiate energy up (into the sheathing and shingles),and down (thru the insulation into the living space). An attic with a noon day temp of 180 degrees radiates many thousands of BTU's into the floor below. Install an attic fan that circulates, say 80 degrees outside air, drops the attic air temps by over 100 degrees (180 down to 80=100 degree temperature differential). Another benefit of cooler attics, your roofing last longer, it's not cooked and dried out from underneath.<br />Attic insulation is easy to install, either batts or loose fill. Be sure not to block the air flow at the roof/outer wall junctions, this is where your soffit vents provide fresh air for ventilation. Building centers have insulation baffles of cardboard or molded foam to keep these airways open. Don't use faced bats, only unfaced. Having a double layer of batts with a vapor barrier on top will hold trapped moisture in the insulation and freeze in the winter. In the winter, your attic should be very close in temperature to the outside air. Proper attic ventilation in the winter is important too. Air-born moisture will condense on the roofing rafters and sheathing. Some folks use both a temperature operated fan with a humidistat to insure that both temperature and humidity issues are addressed. <br />Removing the dome of heated air in your attic with much cooler evening air cools the roof members too. Since the attic temps are cooler when the sun comes up, it takes longer for the heat to build in the attic, again, another plus.

 

[Mercury140-I6]

Re: Would an attic fan help cool my house?

In addition to the attic fans, installing a "Whole House Fan" does a great job of getting the heat out of the house. My parents live in Redding, CA. (The armpit of CA) Not unheard of to get 115 during the day and cooling off to 85 - 90 at night. In those temps AC and the attic fans are the only way to go, but if it does cool off at night in your area, a single (BIG) fan in the celing, will do a good job of pulling the air (Hot) in the house out and cooler air in therough bedroom window's, sliding glass doors or what ever you want open at night. In my area, even when it does get hot during the day it usually cools down at night, I have a pretty good size fan in my bedroom window and it works for my 720sf house.<br /><br /> http://www.myfishingpictures.com/showphoto.php?photo=13003&sort=7&thecat=500&password= <br /><br />Craig

 

[ED21]

Re: Would an attic fan help cool my house?

If you have enough ventilation in the attic, a whole house fan is a great way to go when the air conditioner isn't running. <br /> <br />It can draw in cooler air through the house & blow out the hot attic air. It does this with a minimum of noise & fuss.<br /> <br />I use mine a lot. I prefer it to the A/C except when it gets really hot. <br /> <br />Even if you don't install the whole house fan, you need to vent the attic.

 

[wajajaja]

Re: Would an attic fan help cool my house?

i have a power attic fan on a thermostat and a overide switch to lower the attic temperature,and a whole house fan that blows into the attic from the house on a timer. <br /> they both do quite well, but the wife feels the whole house fan sucks in mini bugs(gnats) too much so we go with central air most of the time.

 

[miloman]

Re: Would an attic fan help cool my house?

I have none of the above. I justr suffer through the intense misery of looking over my hydo bill when its time to play. I think Im going to go and get a whirly bird tomm. Sounds like a good idea