Whole house fan install tip?

[MossRoad]

There is really no debate between an attic fan and a central AC system as far as maintaining a comfort level in an entire house...

Not sure if the trend is still on for large rooms with high ceilings but many were built in the last decade and that increases the demand on an AC system...

With a central system if it is on you are constantly moving all the air in the entire home...whereas with an attic fan you have the option of only moving the air in the rooms you wish...

.... provided you don't have an open concept house. My in-law's house has kitchen, dining, great room all in one. They have three separate bedrooms. High ceilings in the open room - 17'. There is no place to put a whole house fan that would look good, and it wouldn't do much to create a breeze in that huge, open area. The bedroom doors all open to the common area, and you don't want to sleep with bedroom doors open in case there's a fire (I sleep with my doors open, but we always closed the kids' bedroom doors at night). Anywho, whole house fans work better in some designs than others. Even AC and heat don't work that well in an open concept house with high ceilings.

Trying to get old people to leave a ceiling fan on in winter to circulate heat is about impossible. They keep thinking that ceiling fan is using electricity, and it is, but it's moving the heat around and keeping the space heated evenly VS having all your heat staying up in the high ceilings and cold areas along the walls. They complain about the cold and hot spots, I tell them to leave the ceiling fan on, we turn it on, in about 10 minutes they say "that feels much better"..... and when we're backing out of the driveway, we see them walking over and turning it off! :laughing:

 

[California]

with an attic fan you have the option of only moving the air in the rooms you wish...

Our whole house fan, upstairs ceiling to attic, pulls air in noticeably through every window we open, even when there's a window open in every room. Its normal size, 30 inches to fit between joists.

We spec'd additional 'doghouse' vents in the roof when we re-roofed so all that air can escape.

Long ago I tried the type of fan that mounts in an attic end wall vent, intended to cool the attic alone not the house. I couldn't tell that one made any difference.

 

[California]

For that open ceiling house, maybe put the whole house fan venting to outdoors from the laundry room, or even from the garage to outdoors. (with some kind of shutters for winter). Leave the door open to laundry room/garage when the fan is in use. It will still pull air in at every window that is opened. It doesn't need to be at higher elevation than the windows it draws from.

But a whole house fan is only useful if overnight you get lower temperature and humidity outdoors, that you want to pull indoors!

 

[/pine]

Our whole house fan, upstairs ceiling to attic, pulls air in noticeably through every window we open, even when there's a window open in every room. Its normal size, 30 inches to fit between joists.

We spec'd additional 'doghouse' vents in the roof when we re-roofed so all that air can escape.

Long ago I tried the type of fan that mounts in an attic end wall vent, intended to cool the attic alone not the house. I couldn't tell that one made any difference.

Most of the attic venting (gable end etc.) are controlled by a thermostatic switch...so you can tell by the cycle how well they are working...turbans speak for themselves...


Back in the early 80's I was bidding on restoring an old plantation home that had been turned into a few apartments...one of the units had what appeared to be an original attic fan...it was huge...The tenant was there and when asked if the fan still worked he said "yeah man...that thing will suck the flies right off the spaghetti"...

 

[Industrial Toys]

Makes me start to wonder what the electricity draw is for bigger fans, compared to a small AC unit. If you are using a lot of electricity, to move huge amounts of air and not really accomplishing any significant "comfort" that doesn't make too much sense either. I mean, really, you are doing the same in both cases, just trying to relocate heat.

 

[LS Tractor Owner]

Back in the olden days attic fans where very popular here to move the air around enough to help keep the house a little cooler. They did work to a certain degree, and I know some people that liked them. Not enough to not get air conditioning. In the last 15 years or so, I've removed or sealed up about a dozen of them for clients. All where in perfect working condition, they just never use them and they hated looking at them, and knowing that they where huge holes in their attic insulation.

I can't imagine anybody wanting to put one into their house when AC is so effective and energy efficient compared to an attic fan.

I'm cooling a 3200 sq ft house w/ refer air. Using my whole house fan cuts my electric bill by 60-65% over using the a/c. Granted, we use both. The a/c during the heat of the day, then when the outside temps start to drop (usually around 6-7 pm) we switch on the fan. We do live in the mountains, so even in the middle of summer, our overnight temps drop into the 50's and 60's

 

[CADplans]

I purchased a 24" fan that looks like Fuddy's, except it is a heavy duty Grainger (Dayton?) unit, and belt drive
I installed a 1/4HP motor, and checked the current draw,, under 100 watts.
The drive belt was the narrowest I could find pulleys for,, I think it is 3/8 inch wide.

My heat pump is old, and sized pretty close on the needs of the house,,,
The 24" fan is mounted in the gable, and I have several vents cut into the eves where the fan will draw in air.

With the fan off,, on a 90+ degree day,, my heat pump will literally run 100% of the time to keep the house at 75 degrees
Turn on the gable mounted 24" fan, the heat pump will run under 20% of the time.
The fan is thermostatically controlled,, I can tell how sunny the day was by how late at night the fan continue running.
Most hot days it is off by 9-10 PM,, a SUPER hot day it will run until midnight.

My sister's house near Williamsburg performed the same way when I helped her install a fan in her house.
Some nights it is so hot in her attic,, the fan will run ALL NIGHT, and not reduce the attic to the set point of the thermostat.
Before the fan, her attic got so hot, plastic Christmas decorations would melt enough to deform,,,

No air is removed from the living space by my fan,, only attic air is exchanged.
I have 24" (installed depth in 1982) of fiberglass insulation in the attic.

Yea,, the fan runs quite a lot during the day,, but, it only uses as much electricity as a 100 watt light bulb.

I think the electricity I "waste" with the fan buys me a LOT of comfort,,,

 

[Industrial Toys]

At 767 watts per HP, that must be some small (albeit hard working) motor. lol Plus the motor heat, you have to get rid of too.

Is there a point at which you can't shove air into a very hot attic? Because like I said, I tried and failed. If it worked at all, I didn't notice any relief.

 

[JerryK]

The concept of a whole house fan is to remove the heat near the ceiling [ hotter near the ceiling than by the floor ] and exhaust this heat into the attic. The attic during the day is usually unbearably hot. Outside air is drawn into the house thru open screened windows venting the hot air up thru the whole house fan, thru the roof, which also lowers the attic temp. I used to have one years ago and it worked great. You can hook them up using an A/C line thermostat to shut them off at night if it gets too cool inside the house. Some are multi-speed, and you do not have to run them wide open. Even the low setting moves a lot of air. Only real drawback is if you live near a dusty road.

 

[CADplans]

At 767 watts per HP, that must be some small (albeit hard working) motor. lol

Is there a point at which you can't shove air into a very hot attic? Because like I said, I tried and failed. If it worked at all, I didn't notice any relief.

The pulleys I used cause the fan to rotate slower than the recommended speed,, therefore it uses VERY little horsepower.

I am not pushing air into the attic,, I am pushing air out of a louvered gable vent., no living space air is moved by my fan.
Air in at the eves,, air out through the gable mounted fan.

And,, if there is no wind,, you can stand on the ground 20 feet from the house,, and smell the "attic wood" smell.
I am amazed that wood still gives off odor after 40 years,,,

I think the attic fan concept where house air is pushed into the attic only functions further north than where I live.