I am interested in installing a whole house fan in my Mid-Michigan home. Does anyone have any experience with this concept and especially with the whole house low cfm unit distributed by Tamarack Technologies? How well does it work?
Red
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Red
We have a WHF in our 1977 built house in Austin. We love this thing when the weather is cool enough to use it but heres some info that might be useful.
Ours is a large 36" fan with side mounted motor and v belt drive. It's fairly quiet and moves a lot of air. I've seen similar ones in WW Graingers catalog.
One problem is that the standard airflow operated louvers are a big energy wasting hole in your ceiling. Ours leaks like a sieve. I have been planning to go up in the attic and build a large insulated box around ours with a lid that is raised by a pull chain or something. I've seen the Tamarak fan in fine homebuilding and it looks like they have it very well insulated and sealed but I would find out how noisy it is and how much air it can move compared to the type i have.
The other concern is that you want to be sure you cant backdraft any gas appliance vents into your house. As long as all water heaters, furnaces etc are in separate sealed closets this should not be a problem but in our old house I had to seal off two water and one hvac closet because they had vented doors that took combustin air from the house ( UGH ). If someone turned on the fan without opening a window or three you could pull CO out of the water heater chimney into the house.
One thing I also want to do to ours is put a three way switch near the bed so we can turn it off at night. It can get darn chilly later at night,,, maybe a timer would be the way to go.
The other neat thing about a WHF is that not only is it bringing cool air into your house but it pushes hot air out of the attic and can keep the house much cooler on mild days.
Chris
"One thing I also want to do to ours is put a three way switch near the bed so we can turn it off at night. It can get darn chilly later at night,,, maybe a timer would be the way to go."
Definitly. Mine is a 2 speed with a timer. I put it on high when the house has been closed up. But when I go to bed I put it on low and set the timer for about 2 hrs.
Mine is a 30" and I found a plastic cover with an inch of foam that snaps over the louvers in the winter.
I have a 30 inch whole house fan in my home in southeast Michigan and find it to be great at cooling off the house after sunset (and in the morning before turning on the AC. One caveot---realize that when operating a whole house fan creates an excellent draft and flue system to help a fire really get going. I saw test data that had two identical houses, one with and one without a whole house fan. When the fire was started in the house the occupants of the Non-fan home has approximately 2-3 minutes to get out , whereas in the house with the fan running, they had les than 30 seconds before the fire had spread and built up to the same levels.
I shut off the fan before retiring for this reason.
Just a thought.
Stan
I have a Tamarack. It takes a few minutes longer
to move the air than a bigger one would. It does
not require any extra insulation since it is built
in. The folding insulated panels work well.
I understand the new ones have remote control so
you do not need to wire in a switch. Mine is in
the hall and I have to get up to turn it off at
night.
I love it. Roy
The only caveat that I would add to the above is this:
a whole house fan will draw in lots more pollen and dust than just opening up the windows does.
I put a fan in and was shocked after one spring just how thick the yellow-orange layer of (mostly pollen) dust was around each window (and therefore, presumably, in my lungs, on my pillow, etc).
Now I just use the A/C and save the fan for times when I'm working in the attic and can use the fresh air.
Buy the way, there is convincing evidence that cooling your attic space makes little difference in the living space temp on hot days (especially assuming that you've insulated the living space)there were long discussions here last year and the year before about this (warm air rises). I tried it in my place and found that it made little or no difference (and if you're using the AC then exhausting the attic will definitely reduce your cooling ability because you're pulling your cooled air out of your house instead of leaving it inside where you paid for it to be).
Norm,
I agree with the majority of your post except for the point at which you contradicted yourself. If (A) is true than (B) cannot be.
(A) Buy the way, there is convincing evidence that cooling your attic space makes little difference in the living space temp on hot days (especially assuming that you've insulated the living space)
(B) (and if you're using the AC then exhausting the attic will definitely reduce your cooling ability because you're pulling your cooled air out of your house instead of leaving it inside where you paid for it to be.)J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
I switched from talking about "without AC" to "with AC" between paragraphs A and B. I realize now that makes my post unclear.
In paragraph A what I meant to say is that: drawing outside air into your attic space (when you are not using AC) will tend to cool the attic, but the cooling effect will make little difference in the temperature inside the house (in my experience) because the insulation between the two spaces largely prevents the effect of lowering the attic space temp down from 120F to 90F from making a big (noticeable) impact on your inside room air. (I live in SE Michigan so in Atlanta, GA it may be more noticeable but the physics are the same). Now, if you do not have insulation it will be noticeable, more reason why down south it may be more worthwhile than I originally stated.
In paragraph B, running an attic fan and your AC together is wasteful and will tend to make your living space warmer than if you leave the attic fan off (AC on)because the attic fan will draw hot air into your house while you are tying to cool it with the AC.
(the same reason why putting your car AC on "recirculate" will be cooler than if you leave the "fresh" air vent open and are bringing more hot fresh air in all the time).
The common facts between paragraphs A and B:
- hot air rises (convection), and insulation resists the conduction heat down from a hot attic to a relatively cooler room below.
- an attic fan can draw air thru insulation and other penetrations and overload the AC's ability to heat/dehumidify the air in the house (too many air changes / hour).
I should take more time to explain myself, today I feel too rushed.
Now I follow!J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
I'm not convinced on the
I'm not convinced on the supposed lack of benefit of cooling the attic and the effect on inside temps -- although I don't claim any specific knowledge on this.
>>there is convincing evidence that cooling your attic space makes little difference in the living space temp on hot days
What evidence?
I'd test by using an infra-red thermometer and varying scenarios over a number of days. (Remember that it'll take a wghile for heat to move thru the insulation and for the "thermal flywheel" inthe ceiling mass to adjust.)
My (subjective) experience is that a hotter ceiling radiates more heat to objects in the room than a "cooler" one.
And remember, (i) insulation just slows heat transfer and (ii) hot moves to cold.
We've got a roughly
We've got a roughly 30-year-old Sears unit. Maybe 30". It has a louvered door that works remarkably well (we've never had drafts through it -- in southern Minnesota), but in the winter I cover it with an open-ended box sort of cover made from old political signs and duct tape. The cover is light enough that it simply levitates off to the side the first time we use the fan in the spring.
The thing is direct drive, reasonably quiet (more wind noise than motor noise), and has never given us a bit of trouble.
You do need to make sure that you have adequate attic ventilation, of course, and you obviously should open windows before you turn it on, both to let air circulate and to avoid any danger of back-drafting gas appliances.
Some people are whole-house-fan people and some aren't. If you like it you like it, if you don't you don't.
Rats!! Got snookerd by an old message again. Why do these old messages keep popping up?
Ah, I know why! Someone started a NEW thread titled "Whole House Fans" and the system got it confused with the old thread by the same name. Amazing!! (In a rather sick sort of way)
I have a ranch house in SW Michigan. 3 years ago I installed a whole house fan in our Garage. The reason I did this was twofold: I did not want a heat leak in our ceiling during the winter time and I wanted to purge hot air from the attic during the day (but not affect the air in the house). I have lived in several houses that have had whole house fan and no matter how well you insulate them, they will leak heat like a sieve during the winter. The other reason I put the fan in our garage was because our attic space gets very hot during the summer. I wanted to be able to purge the attic of heat during the day when it was hot. In this case I would wait until the heat-activated fan in vent would turn on and then I would turn on the attic fan. Once on, the vent fan would be on for hours. With the whole house fan assisting, I could get the temperature down to the point the vent fan would turn off in about a half an hour to an hour depending on the temperature outside.
Typically, I run the fan at night when the temperature outside is below the temperature inside, then I turn it off when we go to bed, and then turn it back on in the morning leave it on until I go to work or the temperature outside goes above the indoor temperature. This works great for us. We usually open the windows of the rooms (our bedrooms) on the opposite side of the house and allow the air to snake its way through the house. On mornings when the temperature is in the low 60's the house ends up in the mid 60's. Last year we rarely used the ac in our house except on those days where the night time temperature never dipped below 72 degrees. Even on those days we would run the fan to get the inside temperature down to the outside temperature as a preconditioning step before running the ac. I then run the AC to get the house temperature down to about 68 and then turn it off until the heat in the house gets to 78 degrees. Most days that is all that is required. Another benefit of running the fan in the morning is that if the temperature the night before goes below the dew point, the air is quite dry. This is one way to dehumidify the house (to a small degree).
Under most building codes the attic of the house can't "communicate" with the garage.
Here in North Central Texas, I tried living with a 30" whole house fan. We have a fairly high humidity level as well as temps as high as 106 degrees in July and August.
Fans work when the temp is under 85 degrees. Dampness at night isn't comfortable, even if it is somewhat cool. As you pull in outside air, you are pulling in a lot of other things.... Open windows let in neighborhood sounds. The air may have scents of distant skunks. Be sure you have enough windows open or you will pull fumes and smells in air from gas vents and down through your damp chimney and rusty semiclosed fireplace damper. Dust and pollen are pulled into the house, so dusting and Hayfever pills will be needed more often.
If you still want to have one, check the self-closing ceiling shutter for nylon bearings. If the fan is near to your sleeping areas, a cheap, noisy and rattling shutter can take its toll on your quality of sleep. Then, plan to have some type of ceiling insulated and sealed cover to bolt/screw over the shutter framework to keep in your winter heat.
I installed two at each end of the house, but found that one 30" fan was all that was needed. Both were on spring timers. I tried to let them run until 5:00-6:00 a.m. When everything in the "Whole House" was cooled from the night's air, then I'd close the windows to keep in the cool night air of the early months of summer.
Living with all these options, truthfully, I haven't used either fan in 25 years.
Bill
I have both central A/C and WH Fan. For us the deciding factor is the humidity. If the skies are blue, then the air is dry, and the night temp will drop, so the WH fan works well to cool the house in the evening.
If the humidity rises, the skies are grey, the days and nights are muggy, and only the central A/C keeps the family happy.
I can remember as a child in KY that the whole house fan was the only thing that made summer nights semi-bearable. The humidity was about 105%, of course, but still the air movement kept you from suffocating, and made the pool of sweat in the bed a little smaller.