Replies

1. 
   Guest_ | Apr 30, 1999 08:42am | #1

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   Where do you live? My dad put one of these in many years ago so we wouldn't sweat at night and while in theory it was great, it sucked. It was noisey and sucking in hot air is only marginally better. I think ceiling fans would be much better, or do as my mother did and get the AC, of course this was after we all left the house so I got 3-4 days a most out of it before she sold the place. BTW this was in Roanoke,Va, not known for brutal summers.

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   Guest_ | Apr 30, 1999 09:41am | #2

   *VERY noisy, and I think best if you have a house that is badly insulated so that it overheats during the day (for example, our house). Room fans are individually controllable, and the breeze is what is nicest.I put in a gable fan sized on treating the 2d floor of our Cape as an attic. A vent in the ceiling allows air into the crawlspace; I blocked the other gable vent. It is enough to draw a gentle breeze in our bedroom windows and, because it is not mounted in the ceiling, it is quiet. It most definitely helps, but my master plan is to fix the roof & insulate for real.

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   Guest_ | Apr 30, 1999 11:01am | #3

   *Whole house fans work well in climates where there is excessive heat during the day, but with nighttime temps which drop low enough to be comfortable. I've found that the building structure itself will heat up during the day, and unless there is evening breezes, it won't loose heat. (PS Andrew... when its 110F and full sun, any house will heat. I've got radiant barrier, heatmirror glass and R24 walls and R38 ceilings and you still cook.)Invest in a good fan. Belt drive is a must. 6 blades allow lower RPM, and less vibration.If the fan is mounted well off the ceiling joists, and you use vibration isolation, you can reduce the noise. Heck, I hung mine from the roof rafters and then built a flexible connection to the ceiling opening. Given a 4600 sqft house, you can probably find a location away from the bedrooms for the shutter location.Make certain you have enough attic exhaust vent area- remember the fan can only suck as much as it can get out of the attic.A speed control is very nice, and a automatic shut-off is helpful at night.One drawback is that they do suck in a lot of outside air. THis will pull in dust and pollen, and can cause "issues" with the wife and allergy sufferers, respectively.

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   Bill_H. | Apr 30, 1999 12:26pm | #4

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   I've been pleased with our whole house fan, installed 2 years ago. I believe its a Broan brand. 30" diameter, direct drive. I enjoy the optional variable speed control and have added a 12 hour timer (long version of bath fan timer). My first attempt at leaving on all night had me shivering at 3 a.m.. In western Oregon we have about 25 or 30 degree drop in temp. Now we can vent/cool the house in evening, say 9 or 10 p.m. and set the timer for a couple hours or so. The noise is a factor (more so for wife) and the suction can actually slam doors in other parts of house (a rude surprise if asleep). Pick a good location for intake. Seems we used to get a cumulative heat buildup during a several days long hot spell, now we start every morning with the house comfortable. I'd buy as big as available exhaust will allow if you are inclined to flush out hot air and shut down for sleep. Also plan accordingly for intake air. Perhaps small windows (non burgler) that can be left open. If using magnetic alarm sensors perhaps a switch could be set up for choosing closed or open positions on doors/windows. The literature warned of pressure dangers if venting water heaters,furnaces or fireplaces nearby.

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   Guest_ | Apr 30, 1999 07:39pm | #5

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   True, Adam -- our real advantage is this high-tech infrared reduction system called TREES.

   Our fan has a thermostat, so it starts up only when the attic temp exceeds a certain mark. My nerdy sise would like a fan smart enough NOT to start unless the outside temp is significant below the inside temp. I'm also not thrilled at the energy consumption of the larger fans. I'm going to try to set up a chimney of sorts up the center of the house to encourage convection out a skylight. And, as Bill says, be wary of backdrafting in a tight house!

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   Guest_ | Apr 30, 1999 08:06pm | #6

   *Jeff:I install about 2-3 a year, and would refer you to the Grainger catalog. They have a nice little inset article on how to calculate the proper fan size. I don't have the catalog handy, and I am terrible at math, so with that disclaimer, here are my thoughts:The ideal situation is where the home's air is changed over 10-20 minutes. The rating system is CFM for cubic feet per minute. Take your 4600 square feet times the ceiling height, and that will give you your cubic feet. Assuming you have about 40,000 cubic feet of dead air, and want the entire home's air changed in 20 minutes, you would want a fan with about 700-1400 CFM. Do the math.Given the size of your home, and the fact that it is spread out all over one story, I would not recommend a single whole house fan. One area will be like living in a wind tunnel, and the remote areas won't get breeze.Instead I would install several medium sized fans in your attic, in holes cut in the roof. I's put them accross the the back side of the roof along the ridge. This way the back bedroom has a fan near it, and so does the front living room.There are two several manufacturers, put I generally pick Broan. They have a wider variety of sizes (CFM) and most have thermostats, so they turn off automatically when the attic temperature goes below what you set it. They each draw about 2-4 amps. They run about $150 each.For your home, I would install 4-5 fans each with about 250 CFM. I would snake two circuits into the attic, and have them switched at a central location. I would use LED switches so you know they are on. I would set the thermostats at somewhere between 100-110, and dial them in to a comfortable setting over a period of about 2 months of hot weather.Hope this helps, and look at the Grainger Catalog for more details!

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   Guest_ | May 01, 1999 09:17am | #7

   *Andrew,Some RadioShack components and an x10 controller and you can do it.Regarding backdrafting...years ago, we had a minor oven mishap while roasting in the winter. I decided to put the whole house fan and open the sliding door to cross ventilate the kitchen. REgrettably, I did it in that order. By the time I got to the slider, the woodstove had filled the dining and living room with smoke. I was really amazing how quick and thick it got. Ultimately I got enough windows open, and essentially drove the interior down to the outside air temp. Best laid plans.... She didn't stop laughing for days.

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   Guest_ | May 01, 1999 04:32pm | #8

   *I've lived in a house with a ceiling mounted whole house fan for 12 years. On beautiful days it is wonderful to bring the outside freshness into your home. On days of marginal humidity it might make your home a tad more comfortable especially if your basement is dry and you can channel the outside air through the usually cooler basement. On high humidity days which we get our share of in CT you'll be calling your HVAC man for an estimate. The most important advice I can give you is DON"T turn it on before you open enough windows, I have pulled flue gases down my chimmeny from my hot water heater more than once and having to practiccally evacuate the house kind of defeats the whole purpose. I have also found you get more air movement through the house with ceiling mounted versus gable mounted although gable mounted are more effective at cooling the attic space which in turn prevents the house from heating up. If you do opt for AC then on those marginal humidity days remember your pulling in humidity into the house that your equipment will have to remove. Our fan gets the most use on the beautiful days.

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   Guest_ | May 01, 1999 04:54pm | #9

   *I saw something on one of those home improvement shows that you might want to consider. They built a sort of "offset box" up in the attic, and put the whole house fan on top of it. The air came up through the louver, jogged over about 4 feet, and then went up through the fan. The inside of the box was lined wih styrofoam (I think) to deaden the sound of the fan.

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   Guest_ | May 01, 1999 07:16pm | #11

   *Some great ideas here, thanks! I'm remember installations that didn't work, but that must have been due to the installer..

4. 
   Jeff_Baker | May 01, 1999 07:16pm | #10

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   Building a ranch style house with a walk out basement with 4600 sq. ft. Would like to have whole house fan/attic fan to pull outside air in, in place of AC. What is the appropriate cubic foot per minute rating on the fan needed for this size of house?