Whole House Fan

[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]

Originally Posted by mister_two

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]

Originally Posted by gatchel

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]

Originally Posted by 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.

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

Originally Posted by 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.

Originally Posted by 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."

Originally Posted by 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.

Originally Posted by 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.

[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 ass fan mounted in the ceiling in the hall way." It will suck 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]

Originally Posted by 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

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]

Originally Posted by 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.

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]

Originally Posted by 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.

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]

Originally Posted by 472scout

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.