Whole House Fans

[D45]

I am thinking about a whole house fan in the up stairs of my house

My first bilevel had one and it helped cool the upper level so much and so fast, worth it's weight in gold

Any special features to look for?

Any tips or tricks for installation?

 

[sleek98]

Install it at the end of the hallway so it pulls air up the stairs and down the hallway.

Otherwise your choice is a belt drive or a direct drive, I have belt driven ones in both of our houses. Just make sure that you have enough roof vents.

 

[Retlaw 66]

It can be noisy, take that into consideration if it will be near bedrooms.
You'll want to throw insulation over the opening during the winter, so consider access.

 

[johninct]

I have a house that has a very large cupola and I can't believe how much cooler it is compared to my house next door.

 

[fourjeepin]

Make sure the fireplace flue is closed before turning the fan on.

 

[Scott H in Wheaton]

It can be noisy, take that into consideration if it will be near bedrooms.
You'll want to throw insulation over the opening during the winter, so consider access.

You can get white insulated vinyl covers that attach with Velcro, this cover goes on the frame of the fan in the hallway. No more trying to remember if the insulation is there or not, no more climbing in the attic to cover the fan. The orange Big Box store carries them for around $20

 

[6768rogues]

Our state code requires a smoke detector to shut down a whole house fan. Maybe you can find a fan that comes with one. If there is a fire and that fan is running, the house will be gone before the fire fighters get their pants on.

 

[D45]

According to the assessor, my house is 2,088 feet

Does the size determine how large or fan to get?

Obviously the more blades, the more efficient and quiet it will be

My first house, built new, had one......it was loud but worked SO GOOD. In reality, it will only be one for a short time, to pull in/draw in cool air to the upper level so I can deal with noise

What about attic space? Does this also affect the size?

I have soffit vents on two sides of the roof/attic........is this sufficient?

 

[Shiftless]

When I put mine in I had to add alot more attic vents. Here are the pertinant requirements for California title 24 energy guidelines.

Have at least one square foot of attic vent free area for each 375 CFM of rated whole house fan Air Flow CFM

If you don't have enough venting area for the air in the attic to escape, your fan won't pull very much air out of your living space.

Realize that bug screens and louvers decrease the effective area of the vents. If existing bug screens are dirty, the effective area goes WAY down.

 

[wssix99]

^ You all sound like a bunch of Grandpas!!! The big, rattling, uninsulated, belt-driven fans are a thing of the past.

There are much nicer products on the market now. These fans are based off data center fans, are quiet, compact, can be easily replaced, and can be had with integral insulated doors: http://www.tamtech.com/

I have two of these 1000 cfm units to service 5000 sq feet of house and they do great. (One fan is on for Low power and both switch on when we want a faster flow.)

This type of fan flows less air than the giant fans, (the laws of physics still apply) so they don't give the option to have "knock-your-socks-off" air blowing through the windows, but if one is cooling a house with steady flow of cool air from outside - that type of thing isn't needed.

 

[rburke65]

I have a whole house fan and after looking at that This Old House Video, I'm thinking may be time to update. Those new ones are cool.......pun intended.

 

[Falcon67]

That 1000CFM model looks perfect, nice link.

 

[Shiftless]

"You all sound like a bunch of Grandpas!!! The big, rattling, uninsulated, belt-driven fans are a thing of the past."

Proud grandpa here

I have this Dayton 30 inch mounted in a hallway near the center of our one story house. On low speed you can barely hear it. On high it you can of course but then it moves 7600 cfm. Hey, this is GJ right?
I mounted it on high density foam cushions. Even better than that might be suspending it from attic rafters. Louvers automatically open and close.
( I plan to add a fire sensor soon)

 

[wssix99]

Proud grandpa here

he he he

That 1000CFM model looks perfect, nice link.

They are really nice and it's really great to have a super-quiet fan that requires no maintenance or application of insulation as the seasons change.


Getting over the low-and-slow approach to cooling with these is the only adaptation required. They only work when the temperature outside is colder then inside. (Whereas the big belt driven fans may "feel" like they are doing something when the temperature outside matches inside because their high flow makes one feel the wind.) These newer fans are used more like a HVAC economizer.

 

[Firebrick43]

Is their automation available for these fans? Ie you set a degree point, say 69 degrees indoor and anytime the inside temp is above 69 and the outside temp is cooler than the inside the fan comes on?

Is ridge vents enough ventilation? Is there some kind automatic intake air vents as well for really tight houses?

Thanks

 

[wssix99]

Is ridge vents enough ventilation?

They could be. The instructions give the minimum surface area of venting required- so you'd have to calculate how much ridge you have open and measure it up.

Is there some kind automatic intake air vents as well for really tight houses?

There are snorkel systems available for tight houses, but all the ones I've seen ****. When the wind blows across a house, negative pressure builds up on the back side of a house and it looks to me that this could open the snorkel and let cold/hot air in when not wanted.

In our case, we only run these fans manually, so we are careful to open a window or two first. (We already have the negative pressure problems typical to tight houses...)

Is their automation available for these fans?

No. They aren't intended to be an economizer. So, if you want that, you can get a commercial economizer module to add to your HVAC system. That will come with automation, venting, etc. (If you are putting this in your ICF addition, you'll have to cut some holes...)

You could make your own automation for the fan, but you'd still have the pressure relief problem that you allude to above. It would be possible to put mechanical louvers in, but I expect that you'd have to search for a while to find a well-insulated system. (See Modern Jess' comments - http://www.garagejournal.com/forum/showthread.php?t=337783)

 

[Falcon67]

Is their automation available for these fans? Ie you set a degree point, say 69 degrees indoor and anytime the inside temp is above 69 and the outside temp is cooler than the inside the fan comes on?
Thanks

Look into something like the Ecobee 3 thermostat.

http://www.smarthomehub.net/forums/...e-connected-their-ecobee3-to-a-whole-home-fan

Another plus for a whole house fan - you can do a blower test on your house. You may well be surprised at where air leaks into your conditioned space.

 

[D45]

I did a re-check.........I have soffit venting around three sides of the main attic (where the fan would go)

I also have two cheap-o square vents cut into the roof

 

[Bruce 993 SEA]

If I were to put in another whole house fan I would go for this one:

https://www.wholehousefan.com/quiet-cool-qc4700/

There are various sizes...

The motor and fan are suspended in the attic on nylon straps so they do not rumble.

Almost pulled the trigger at the old house but we moved. This place has minimal attic with scissor trusses...

Cheers!

 

[D45]

A lot of varieties to choose from, a decent selection at the big box stores

A ton of choices online

I am wondering about the install myself compared to paying someone.....seems like labor/install prices are crazy expensive

 

[D45]

This site says 3,000 CFM - 4,000 CFM for most 2,000 square foot houses

https://www.wholehousefan.com/products/

https://www.wholehousefan.com/sizing-a-whole-house-fan/

 

[mike93lx]

I have one but never use it. Don't like the idea of dumping all that hot and humid air into my attic, regardless of how well it is vented. I'll be removing it soon when i have the time to patch the drywall.

 

[wssix99]

This site says 3,000 CFM - 4,000 CFM for most 2,000 square foot houses

https://www.wholehousefan.com/products/

https://www.wholehousefan.com/sizing-a-whole-house-fan/

If you go to see a Ferrari dealer, they will tell you that most 40-60 year old men require hand stitched Italian leather, also. (They do, of course.)

The CFM is an empty measure unless you are getting into a "mine is bigger than yours discussion". The actual flow of air will depend on how many windows are open, how the attic is vented, etc.

For example:

If you have a 3000 cfm fan and you open the windows in one room, you are getting 3000 cfm of flow through one bedroom. If you have a 3000 cfm fan and open the windows in three rooms, you are getting 1000 cfm-ish of flow in each bedroom.

^ So a lot of the adequacy depends on the use, and not so much the size of the house. Likewise, CFM works a lot different in a house with 12 foot ceilings vs. a house with 8 foot ceilings.

 

[like2wheel]

I have one but never use it. Don't like the idea of dumping all that hot and humid air into my attic, regardless of how well it is vented. I'll be removing it soon when i have the time to patch the drywall.

I know this is from 6 years ago, but I gotta ask: do you somehow have conditioned air in your attic?

Trying to understand how the air from inside your home mixed with what comes thru the windows is somehow hotter and more humid than what's in an attic space.

My attic welcomes the fresh air forced up there by my whole house fan. I think that's why my 29 year old shingles still look so good.

 

[toplessHO]

last house I put one in the hallway closet ceiling
I had to drop the louver down 6 inches to clear rafters so lost 6 inches of ceiling in there.
I paid $20 for it at Sears on clearance.
Pulled it out when I moved and its now on a cheap hand truck as our mobile garage fan.
Current house I put a big Dayton fan in the garage loft. I can turn it on and open a door or window
in the house thats on adjacent wall and pull air thru the house too.
Its really nice when spray painting or running a car(with garage door open).
I love it when its cool and dry enough to run.I put a firestat on attic fan on house #1.

 

[Innovate1]

From a BS perspective, are these products good, bad or merely useless?
I define a whole house (WH) fan as one which is intended to pull air from the living space, whereas an attic fan is meant to pull air only from the attic.
A WH Fan seems benign and maybe even usefull if used to pull cooler outside air into a hot home in the summer months as long as the humidity being pulled is not harmful.
The attic fan seems more complicated. The most recent as I noticed is in USA Today this morning from SolarTube. It is meant to pull air through the roof from the eave vents, thus cooling the attic. It would seem to "short circuit" the ridge vent. If there are leaks in the second floor ceiling it might pull conditioned air (and maybe mositure) into the insulation above the second floor ceiling. Does cooing the attic have a measurable affect on the home interior temp anyway?

Attic fans aren't that effective in most cases from the studies I have read. As long as you have a good amount of ventilation powered fans or turbine vents aren't going to do much better and may use more energy than they save.
Whole house fans are great for "free" cooling in areas that get cool, low humidity nights. Our area has high humidity in the summers so most of our use is in the spring and fall. I watch "dew point" rather than relative humidity (which is what people commonly use) as it's an absolute measure of moisture in the air. Studies have shown that above 60F dew point starts to get uncomfortable. If the dew point is 60 or less I open the windows and turn on the WHF. In the morning turn it off and close the windows. Thinking about how to automate it but need some motors for the windows.