Whole House Fan

[lzenglish]

Get one, if you want to save energy, and piss the wife off! LOL! Yes, A Whole house fan is a way of life, as you need to use the cool/cold morning outside air, to cool the house, and attic space ,in the morning hours, which will keep your DX A/C unit from running, at far below the normal A/C energy cost. Downside: Possible Pissed off cold wife, a little more dust in the house, (which can be fixed by a couple of electrostatic air filters in the bathroom windows, which I'm working on, And, possible security problems, as you need a minimum of 2 square feet of intake opening, to run one. I use a pit bull, a 12 guage shot gun, and a whole house security alarm system, for the security aspect. If you do spring for one, buy a good one, and not a rattle trap from the big box store. I have had my Dayton 36 inch from Grainger for over 20 years now, and it is very quiet, on low or high speed. So far, this season, we have hit over 90 degrees O.A. at least 10 times, and I have not had to run my DX A/C yet. My whole house fan has a 1/3 hp motor, verses my 3 HP DX Compressor Motor. Just food for thought!, And IMO !

Wayne

 

[JakeKohl]

I bought a Tamarack for my 2nd story office above my garage. The space isn't finished yet but I have tested the unit and it's really neat. It has thick foam insulated doors on top (in the attic space) that slowly open when the unit is turned on. Once open, the fans start up. It solves the insulating issue with most whole house fans and it installs in one standard joist bay so you can avoid having to box in any new framing. They're a little pricey but they have some good features and seem well built.

The unit I have in that space is the HV1000 and I hope to get one of the higher capacity 1600 units for the house soon.

http://www.tamtech.com/store/fans-whole-house-fans-alternative-cooling,category.asp

 

[BadgerBoilerMN]

Obsolete technology for some time now. Think HRV or ERV and proper sizing. Direct exhaust fans assume perfect outdoor temperatures and humidity-rarely available at the same time in most climates.

 

[tdkkart]

Obsolete technology that still works very well. Pay attention to your surroundings, cool the house down before the big temps hit, and then close the house up. Works great for us, and is the plan for tonight before the 90+ temps hit before the weekend.

 

[Jackfre]

Our house in MA had one. Used it all the years we lived there. The last few years I had the mini-split hp installed but we had good service from the whole house fan. We would wait until the sun got low in the afternoon sky and open all the windows and let'er rip. Huge air flows. pull the bed covers down to cool it off. Sometimes we ran it all night and you could close doors and windows to concentrate air flows. Just like everything, you live with it and you learn how it best works for you. Come morning, close the windows and preserve the cooler mass in the house. Come winter I had a 4" ridged insulation cap to drop over it to seal it off. It cost a boat load of kw to run that thing, but at the time it was what we had. Oh, and when something got burned in the kitchen nothing worked better at getting rid of that air.

I believe that Panasonic makes the best of them today.

 

[JakeKohl]

Obsolete technology for some time now. Think HRV or ERV and proper sizing. Direct exhaust fans assume perfect outdoor temperatures and humidity-rarely available at the same time in most climates.

I don't agree that it's obsolete. My house was originally built without air conditioning...and it's pretty darn cost effective.

 

[tdkkart]

I don't agree that it's obsolete. My house was originally built without air conditioning...and it's pretty darn cost effective.

 

[malibu101]

I don't think it's obsolete technology either.
I think it's old technology that's a comeback due to time tested and proven results.
And like was said- If used properly is quite energy efficient.

 

[allinon72]

I have one and LOVE it. It was already installed when we bought the house and I didn't know much about it. The sucker has a huge motor that nearly trips the breaker when turned on and it can MOVE some air.

 

[Greatbear]

I would never have a house without one. Mine gets used more than the a/c by far.

 

[BadgerBoilerMN]

I stand corrected.

It was never a good idea in climates with nighttime dew-points below 50°F.

In N.Cal or Maine, maybe even along the coast in the Carolinas, OK; but I have spent a lot of time in Eastern, IA and some in Indiana...I don't think so.

That is, if the humidity goes up at night (as it is bound to do in a good part of the country) then running a DX unit (A.C.) (the main function of which is to dehumidify the space) then you are fighting a losing battle. In fact I have had to tell may clients here in Eden Prairie, MN that the "A.C." will not keep up if they like to open their windows for sleeping.

Naturally after a nice storm like we had last night opening a window to temperatures and humidity 35 points lower than noon yesterday makes perfect sense. But a loud, electrically inefficient whole-fan with requisite "balancing" of windows etc. You can have it.

Most people need cooling in the dog-days of summer when humidity and temperatures are high day and night. On those days a whole house fan isn't as efficient as a ceiling or a box fan for that matter.

If you really want to go retro get out on your sleeping porch and shut off the noise and the electric bill at once.

To quote another smart guy: "The low to mid-speed COP of a 1 ton 20+ SEER mini-split is into double-digits when it's 75F outside/80F inside. It can remove more heat (both sensible & latent) cruising at 200-300W than a kilowatt of whole house fan under those conditions. (And it's quieter, and it doesn't create a mid to large sized infiltration leak-point to raise the average heating & cooling loads the way whole-house fans usually do.) But when it's 65F outside 80F inside the whole house fan can probably beat it on sensible-cooling efficiency."

 

[6768rogues]

Our code requires that a whole house fan be interconnected with a smoke detector. With the fan running, if a fire starts, it will pull the fire through the house and into the attic in a matter of minutes.

 

[BD1]

I'm in Northern Illinois and put one in 30 years ago. It's in hallway ceiling discharges into attic. This moves all kinds of air. I would never be without
one. You get a warm day, house closed up; night time outside cools down. Turn fan on and instant cool down . I have mine wired on a variable speed switch.

 

[54FordPanel]

I'm also a big believer in whole house fans.
I put them in all my houses that I've lived in.
I get up in the morning, and pull cool air in, and push the cooler air into the attic. In the afternoon, I turn it on again to force all the really hot air out of the attic, then I turn on the swamp cooler, which is ancient technology but is $$$$s cheaper than A/C and works great in Colorado.

 

[Sureshot]

I think they need to come up with one with a PLC to shut it off when the intake temp exceeds the exhaust temp. That would be awesome in the shop as well.

 

[Relie]

I installed one in my house 25 years ago and it worked great for years. A few years ago I installed central air and removed the fan. Guess where it went? Right out to my new garage. I have a 24x40 with no windows and this fan cools it off nicely. So, you see mine served double duty. lol

Dave

 

[gatchel]

Our code requires that a whole house fan be interconnected with a smoke detector. With the fan running, if a fire starts, it will pull the fire through the house and into the attic in a matter of minutes.

I know why but find this interesting. As it is pulling the smoke out, it is also pulling fresh air in from somewhere to feed the fire...

 

[venom50svt]

One thing that puzzles me is that the CFM rate of the fan. Does'nt it need just as much of an escape route at the same rate??? Is that possible with a standard ridge vent and maybe soffit vents?

 

[JakeKohl]

One thing that puzzles me is that the CFM rate of the fan. Does'nt it need just as much of an escape route at the same rate??? Is that possible with a standard ridge vent and maybe soffit vents?

a standard ridge vent doesn't do you any good without a plethora of soffit vents...but yeah, you need adequate ventilation. A ridge vent system should have a LOT of soffit ventilation to maintain flow and should be able to support the fan exhaust.

 

[mister_two]

What's the difference between this type of fan and a attic fan to cool the whole house? My situation: I have a ranch single family house outside of NYC, about 1200 sq feet. A brick house built in the 50s. When we moved in it had wall A/C units. We replaced them with 2 Fujitsus split A/C. They work fine although the bigger unit in the living room could use some help on really hot days. We turn on the units when temps start to hit 80s. Yesterday was a a good example it really wasn't THAT hot outside, maybe in the low 80s but in our house it's HOT. There are plenty of windows in all directions in our house but even with all the windows open the place is hot and end up going to the A/C. I am starting to investigate on ways to lower the temps for the whole house. Would something this whole house fan fit the bill? Or is there a better solution out there? Thanks for any advice.

 

[green.bubbly]

I grew up with no air conditioning. Just a huge whole house fan mounted in the ceiling. I remember the linoleum rub in the dining room would rise off the floor when that fan was one and the doors closed.

I also remember sweating like a pig at night while sleeping. Way too damn hot and humid here for that. Although there are a few days in the winter where it would be nice to have one.

 

[Falcon67]

What's the difference between this type of fan and a attic fan to cool the whole house? .

An attic fan will pull air in from the attic vents and may reduce attic temps. Better to look at your venting situation first. They work best with gable vents and maybe soffitt vents. A whole house fan pulls air in through the windows and blows it out the attic, sort of doing both. However, if it's 100F outside, thats what is coming in. The usual "trick" was to run them at night to pull in cool night air, then shut them down during the hot days.

Note - Old houses with attic fans usually had big, wide and hand made gable vents. They move 4500CFM or more of air, so that air has to be let out somewhere. A more modern house with some eve and roof vents will not have enough vent area to let that much air out.

 

[Jackfre]

There are two types of cooling. Latent, think of it as humidity reduction, and Sensible, think ofit as temperature reduction. Your Fujitsu's (model and size, please) and any inverter (true variable speed unit) controlled ac will run at very low speed initially and just wring the moisture out of the air. Once the latent is taken care of the temp reduction begins in earnest. My suggestion would be, based upon the dreadful temp AND humidity that you are faced with recently that you turn it on and leave it on in these really max temp and humidity conditions. I always recommend undersizing, to a degree on residential systems. Your description of your house, windows everywhere, may just be putting to much of a load for "instantaneous" cooling and dehu.

Outside of Boston in the type conditions you describe I would run the whole house fan. My bed was right in front of the double windows. The flat out velocity of air would cool me, but with the humidity, I was still peeling the sheet off my back. When it was all I had, it was great!

 

[6768rogues]

I know why but find this interesting. As it is pulling the smoke out, it is also pulling fresh air in from somewhere to feed the fire...

You are correct. Keeping a fire confined to one compartment gives the fire department a chance to save something. Creating a draft is not good in a fire, especially a fire that occurs when everyone is sleeping. Once the fire reaches the attic, it is hard to save the house.

 

[jonesmechanical]

Obsolete technology for some time now. Think HRV or ERV and proper sizing. Direct exhaust fans assume perfect outdoor temperatures and humidity-rarely available at the same time in most climates.

This is 100% incorrect. The function of HRV/ERV's is to ventilate the house while protecting the home from the outdoor temperature and humidity (in the case of a erv).

If to goal is to take advantage of the out door temperature to passively cool your home, then a HRV/ERV will actually work against you in doing that.

A recent code adoption here in Utah requires us to provide a air pathway that opens/closes when ever that there is a kitchen hood fan over 400 cfm. Many of the home we work on have hoods over 1200 cfm, and the last home we had issue with had two 1200 cfm remote blower kitchen hoods.

Well, the outside air damper (OAD) that provides this fresh air in this case was sized at 14"x48". We also have a return air damper (RAD) and a mixed air sensor (MAS) so that the air from the outside can mix with the indoor air, and the dampers can modulate depending on how much make up air is needed for the kitchen hoods.

When the OAD and RAD modulate and work together, if the MAS indicates a temperature too low before the furnace, there is a electric element heater that tempers the air. In the case of air that is too warm, the air conditioning compensates for this.

With all this work, I figured, "HMM, here is a good opportunity". Well we setup a honeywell Jade controller to allow for passive cooling. Depending on the actual pressure of the house, we have a Tamtech insulated attic fan that receives a 2 speed input from the Jade controller (that changes speed based on how far closed the RAD is.

There are 4 zones in the house, and all of the passive cooling is automated through the Lennox Harmony III zone system and the Honeywell Jade Economizer control. All of the parameters are adjustable (at what point the attic speeds turn off/1st/2nd speed; when the outside temperature is allowed for cooling etc).

When the indoor thermostats indicate that the home needs cooling and it happens to be cooler than 65 degrees (this is how we have it setup for Park City) the cooling call from the Harmony III zone panel is intercepted and the RAD/OAD modulated depending on the MAS (set at 50 degree target minimum, so it its zero degrees, it mixes more indoor air with the outdoor air). The DX cooling (2 stage) or the outside air economized is completely automated, and if there is any pressurization in the building, the 2 speed attic fan is activated. If the indoor kitchen hoods are activated, the attic fan stops, and they act for the method of depressurization.

The net impact is a simple to operate system that addresses make up air for the kitchen hoods, while doubling as a passive cooling system.

Also to note: All of the bathroom air extraction in the home is performed by two Venmar HE2.6 High efficiency HRV's. At first the builder was insistent that the HRV's would provide the needed makeup air for the Kitchen hoods. It took him a while to understand that there is a fundamental difference between fresh air (when provided by HRV/ERV) and makeup air. Fresh air when provided by a HRV/ERV is completely balanced by the nature of its operation because it brings in the same air that it exhausts. Makeup air provides the balance to a exhaust system that a HRV/ERV already by its design.

 

[BadgerBoilerMN]

No way.

You have an ocean over there, right?

You have the perfect solution for your climate with the highly efficient air-to-air min-split. If you leave the windows closed in warm, humid, weather and keep the house below 50% relative humidity, you will be comfortable in all weather.

Keeping the house open and full of latent heat and then closing up and turning on the AC when you can't stand it anymore is missing the whole point-not to mention ignoring basic design criteria. Most human discomfort in hot weather comes from the humidity. This is certainly the case in New York.

Try leaving the place closed in July and August, set and forget the thermostat at say 78°F and see if you aren't happy.

If you don't mind suffering, the wasteful inefficiency, unnecessary noise and wasted material and labor should not bother you.

 

[BadgerBoilerMN]

I think you have both the scale and the climate mixed up in this debate.

Whereas, there may be a few days in a few climates, such as high arid plains and mountain areas where an obnoxious "whole house fan" placed in an attic and balanced by opening this window and that may "work" for some folks. The vast majority of people will not benefit from this crude technology.

I have lived in many parts of the country from CO, and NM to OH and MN. All have design conditions that require special consideration. That's why I use Wrightsoft to keep it straight.

To compare a whole house fan to a sophisticated economizer (exclusive to commercial installations except perhaps in the small hotels some folks who "live" in Park City call "home" is off the subject.

Note that we in Minneapolis are beyond summer design conditions at 100°F and 80% rH and you in Park City are suffering 84°F and 21% rH. By all means, open a window!

Give me a nice tight house in any climate and I will be comfortable...OK grass hut in Hawaii, no HVAC needed.

 

[Charles (in GA)]

Four posts and nothing to add to the discussion except you don't like attic/whole house fans, which are quite efficient and workable in many areas of the country. SOME people DO actually like the smell and feel of the outdoors, and just want to stay cool.

Charles

Obsolete technology for some time now. Think HRV or ERV and proper sizing. Direct exhaust fans assume perfect outdoor temperatures and humidity-rarely available at the same time in most climates.

I stand corrected.

It was never a good idea in climates with nighttime dew-points below 50°F.

In N.Cal or Maine, maybe even along the coast in the Carolinas, OK; but I have spent a lot of time in Eastern, IA and some in Indiana...I don't think so.

That is, if the humidity goes up at night (as it is bound to do in a good part of the country) then running a DX unit (A.C.) (the main function of which is to dehumidify the space) then you are fighting a losing battle. In fact I have had to tell may clients here in Eden Prairie, MN that the "A.C." will not keep up if they like to open their windows for sleeping.

Naturally after a nice storm like we had last night opening a window to temperatures and humidity 35 points lower than noon yesterday makes perfect sense. But a loud, electrically inefficient whole-fan with requisite "balancing" of windows etc. You can have it.

Most people need cooling in the dog-days of summer when humidity and temperatures are high day and night. On those days a whole house fan isn't as efficient as a ceiling or a box fan for that matter.

If you really want to go retro get out on your sleeping porch and shut off the noise and the electric bill at once.

To quote another smart guy: "The low to mid-speed COP of a 1 ton 20+ SEER mini-split is into double-digits when it's 75F outside/80F inside. It can remove more heat (both sensible & latent) cruising at 200-300W than a kilowatt of whole house fan under those conditions. (And it's quieter, and it doesn't create a mid to large sized infiltration leak-point to raise the average heating & cooling loads the way whole-house fans usually do.) But when it's 65F outside 80F inside the whole house fan can probably beat it on sensible-cooling efficiency."

No way.

You have an ocean over there, right?

You have the perfect solution for your climate with the highly efficient air-to-air min-split. If you leave the windows closed in warm, humid, weather and keep the house below 50% relative humidity, you will be comfortable in all weather.

Keeping the house open and full of latent heat and then closing up and turning on the AC when you can't stand it anymore is missing the whole point-not to mention ignoring basic design criteria. Most human discomfort in hot weather comes from the humidity. This is certainly the case in New York.

Try leaving the place closed in July and August, set and forget the thermostat at say 78°F and see if you aren't happy.

If you don't mind suffering, the wasteful inefficiency, unnecessary noise and wasted material and labor should not bother you.

I think you have both the scale and the climate mixed up in this debate.

Whereas, there may be a few days in a few climates, such as high arid plains and mountain areas where an obnoxious "whole house fan" placed in an attic and balanced by opening this window and that may "work" for some folks. The vast majority of people will not benefit from this crude technology.

I have lived in many parts of the country from CO, and NM to OH and MN. All have design conditions that require special consideration. That's why I use Wrightsoft to keep it straight.

To compare a whole house fan to a sophisticated economizer (exclusive to commercial installations except perhaps in the small hotels some folks who "live" in Park City call "home" is off the subject.

Note that we in Minneapolis are beyond summer design conditions at 100°F and 80% rH and you in Park City are suffering 84°F and 21% rH. By all means, open a window!

Give me a nice tight house in any climate and I will be comfortable...OK grass hut in Hawaii, no HVAC needed.

 

[skyking]

We always called them attic fans in Dallas.We also had water coolers (some call them swamp coolers.) I now live in Okla. my house (built in 1986 ) has an attic fan." Big *** fan mounted in the ceiling in the hall way." It will **** your shirt off.We love the noise it makes. Terrible for someone with allergies. We love it.Only use it when it is pretty nice outside .
When it gets hotter (above 75) we turn on the a/c and keep it at 72 deg. all the time.
Screw the elec.bill ....we gotta be cool.

 

[Sureshot]

Four posts and nothing to add to the discussion except you don't like attic/whole house fans, which are quite efficient and workable in many areas of the country. SOME people DO actually like the smell and feel of the outdoors, and just want to stay cool.

Charles

You ruined it for me Charles. I was feeling all special because I thought I must live in the only place where it worked to cool the house with outside air at night and close things up during the day. We don't have AC and for all but a few days a year that is fine. We do have AC in the camper and the basement is always cool.

 

[tdkkart]

No way.
You have an ocean over there, right?
You have the perfect solution for your climate with the highly efficient air-to-air min-split. If you leave the windows closed in warm, humid, weather and keep the house below 50% relative humidity, you will be comfortable in all weather.
Keeping the house open and full of latent heat and then closing up and turning on the AC when you can't stand it anymore is missing the whole point-not to mention ignoring basic design criteria. Most human discomfort in hot weather comes from the humidity. This is certainly the case in New York.
Try leaving the place closed in July and August, set and forget the thermostat at say 78°F and see if you aren't happy.
If you don't mind suffering, the wasteful inefficiency, unnecessary noise and wasted material and labor should not bother you.

Attitudes and advice like this is the reason I look at my neighbors utility bills and find that they pay 50-100% more than I do.
The neighbor gal was whining on Facebook that their A/C was broken......it was SIXTY FOUR degrees outside!! DUH, open the damn window!!!

 

[tdkkart]

Four posts and nothing to add to the discussion except you don't like attic/whole house fans, which are quite efficient and workable in many areas of the country. SOME people DO actually like the smell and feel of the outdoors, and just want to stay cool.

Our A/C has been on for less than 2 weeks this entire summer season. Whenever the nighttime temps are forecast to be below 68 degrees our whole house fan gets turned on overnight. In the morning the windows are closed and the house stays perfectly comfortable well into high 80deg outdoor temps.

 

[Jay H 237]

Ours runs often this time of year, it's a two speed, belt driven Dayton unit. Mounted in the hallway cieling pulling cooler air into the house and pushing the hotter attic air out.

The house built in 1989 has no A/C, not easy to add being 3 stories and hot water baseboard (no ducting).

 

[tehach]

We use ours to pull in cool outside air and to exhaust hot attic air. Works great, minimal cost, I wouldn't be without one.

 

[472scout]

Any recommendations on a good unit for a 3000 sf home?

 

[lzenglish]

Any recommendations on a good unit for a 3000 sf home?

YES, I would go with the Dayton 30, or 36 inch whole house fan, with quiet louvers, sold at Grainger, at a near wholesale price. If you work in the HVAC field, or your company buys from Grainger, you can get a Employee disscount price, with free next day shipping, to your front door, if you order before noon the previous day! At least this has been the case with me for 30 years now.

Wayne

 

[pseudorealityx]

I think it's an acceptable solution for a lot of people. It grows less acceptable as you move towards the SE USA, as the humidity levels just get ridiculous for more of the year. Which is the same reason why even many commercial systems are not required to have economizers in the deep SE. That said, I know friends in the Atlanta area who have and use them, and they work 'ok'. My biggest problem around here is that we get such terrible pollen seasons during the spring when these things would be perfect to use. YMMV.

All that said, it would be smart to have a humidity sensor so that people can make more intelligent decisions on when to use it vs. the A/C. Badger was right that humidity is more 'annoying' to people than heat in many cases.

 

[luv2diy]

Another good read! I found a formula online and thought I’d post to help any other fellow GJ’s cut down on research time. The required CFM for my house is ~4900. What are your guy’s thoughts on Direct drive vs belt drive?

Design Considerations:
• For maximum effectiveness, a whole-house fan must be sized correctly for the structure it is required to ventilate.
• The formula to follow for determining capacity is: square feet of living area x 3 = CFM (cubic feet of air moved per minute) required.
• Because whole-house fans exhaust hot air into an attic, a properly sized attic ventilation system is required to exhaust heated air from the attic to outdoors.
• To determine the net free area of attic ventilation required, use the following formula: CFM rating of fan divided by 750 = square feet of net free exhaust area.
• Failure to provide this venting will reduce the fan's airflow capacity. In addition, it will lead to noisy operation and ultimately failure of the fan motor.



Direct Drive
24” 4500 CFM 1500 HOME SQ.FT
30” 5700 CFM 1900 HOME SQ.FT

BElt-DrivE
30” 5700 CFM 1900 HOME SQ.FT
36” 6900 CFM 2300 HOME SQ.FR

 

[Jagmandave]

It does depend on where you live.....

In Sandy Eggo where I used to live I didn't even have A/C, but I did install a whole house fan, and it was wonderful.....but we usually had 50 or less humiditity. Where I live now, here in KC, the humidity is crazy high, so I can't see it being as useful, except on those rare nights when the humidity drops.

I understand the mass temp reduction and so on and I agree in principal, but here where it's soooooo humid, I have to use the A/C till about early to mid Sept.

If I lived in Colorado, it would be perfect with their low moisture......

 

[Zelatore]

I stand corrected.

It was never a good idea in climates with nighttime dew-points below 50°F.

In N.Cal or Maine, maybe even along the coast in the Carolinas, OK; but I have spent a lot of time in Eastern, IA and some in Indiana...I don't think so.

That is, if the humidity goes up at night (as it is bound to do in a good part of the country)

Well there's your problem...you're obviously confused about where the good parts of the country are. You see, the good parts don't have 60-70-80+% humidity like the south and the Midwest.

FYI, mine is running right now. Far cheaper and faster to cool the house off with it at night than to try the craptastic heat pump we have that literally can't bring the second story bedrooms below 80 without setting the thermostat to 60 and running constantly. As long as the daytime highs don't exceed the low 90s I don't even bother with the A/C.