I'm not really a fan of attics.

This is literally my business…attic fans and Wholehouse fans.

Attic fans are good if you can change the shutoff temp remotely IE a phone app or simple bypass switch. You WANT to be able to have the fan run at night to pull in cool evening air. An attic fan with a thermostat set at 110F will shut off at 110F, which means the best your attic temp will reach is 110F.

Have your electrician wire a T-Stat bypass switch into the house, or buy an attic fan with a phone app. There’s a company that makes app driven fans, but they are anti 2A so I won’t mention them by name,

IM me for details.

I added solar powered attic fans and my overall power consumption went down on a 3,300 square foot house in west texas.

As long as you have soffit vents, you should be fine.

Keep an eye on it, ten years is pretty good for one of those.

Get three quotes on a ridge vent install.

it depends how cool it gets at night. running a house fan is much more energy efficient than an AC.

a friends cabin has one, he doesnt have AC as its off grid. it works very well but its in the mountains where it never really gets over 90 or so and thats rare. every night it gets cool so we just opens the windows uses the fan when the sun sets and closes them when it rises.

Very similar to this:

I don't think attic fans are worth the money.

1. They do nothing to reduce the heat the sun has created on the structure of the house through radiation.
Radiation has already cooked the structure of your house and an attic fan won't do much to lower that generated heat.

2. They don't really create enough push or draw to actually get the air in your attic to move.
Generally a properly sized attic fan would need to be the size of an F-4U corsair propeller to move enough air to be effective.
If your house is a square or rectangular box it might help, the minute you add in gables, L or H shaped house designs, multiple stories the effectiveness of one fan is moot.

3. Depending on how many other openings in your roof there are and their location make the fan less effective.
Air, like water, takes the path of least resistance.
If you have a ridge roof vent or multiple gable vents or under eve vents the air is going to go in or out the closest vents depending on there the fan is located.

4. If your house is not well sealed an attic fan can pull conditioned air from inside of your house or push hot air into your house.

As has been mentioned in this thread, I think the best way to start is to foam spray the underside of the roof sheathing or install a thermal barrier (or both).
Get rid of that shit blown in insulation and go with a rolled in fiberglass insulation, a minimum of an R30.

Of course I could be wrong.

A house we lived in several years ago got hit by a tornado, and when we had the roof replaced we added an attic fan.  It was thermostat triggered, and made a noticeable difference in the temperature upstairs during the summer heat.

how did you come to these conclusions? Are you a GC or roofing contractor?

When you say "attic fan," it sounds like you're describing a fan to exchange air between the attic and the outside.  My last house had two of them, and they make a huge difference in how hot it is in the attic in the Summertime.  When one died, I had to go up there in the Supper and replace it.  I had the breaker off, so the other wasn't running either.  Hot as hell, even in the morning.  When I was done, and my wife flipped the breaker back on, turning both fans on, it was almost instant relief.  The air temp dropped probably 20-30 degrees in seconds.  Each fan has a thermostat that turns it on only when it's hot in the attic.  They blow hot air out at the roof peak, and suck in air from the soffits.

There is also what I've always heard called an "attic fan" that is a giant blower that sucks air up from the inside of your house and dumps it into the attic, which when your windows are open, will suck air from outside into the house.  My parents' house (circa 1965) has one.  In the Summertime, they ran it a lot, creating a great breeze in the house, and I'm sure it used a lot less power than the air conditioner.  Don't run it during pollen season or when it's rainy/wet outside.  There have been times when I wish I had one in my house.  I think they're also called "whole house fans."

I don't think they do a lot, and I'm a fan of KISS.  Which these are.



No mechanical systems, motors, or power systems involved.

Should be solar powered...only needed when the sun is heating the attic!

Same here, with closed cell insulation sprayed on the interior of the roof you don't need attics any more, you can have more living area now.

Well you need to make sure you have enough eve vents to let air come in easy vs the cfm.

Ridge vent with soffit vents would be better.

Turbin vents work great here. We have lots of wind.....

This thread is fun. You have those with out them saying they are useless or to use other options like ridge vents. Then you have those who have them say it makes the upstairs cooler or the AC work less.

needs to go the way of the dinosaur. Ugly, high profile and the top comes off all the time. I have probably fixed hundreds of these by replacing them with a low profile dormer or redoing the ventilation system and going to ridge vent.

They only metric you need to be concerned with in regards to attic venting is CFM on powered vents and NFVA on static intake and exhaust

That's nice.  I've done both, and there wasn't any difference.

Gable fan and roof vents….

On page 1 I wrote what the ventilation requirements are for ever major roofing manufacturer and current residential building specs. The best system is a large ridge vent with the proper ratio of intake vents, coupled with a whole house fan and it really kick ass if you know how to use that system.

I don't like powered gable or roof mounted vents. I have seen several house fires start from both, plus you have to rely on electricity to make it work and then you get noise and or vibration issues from them.  For what they actually do, there are better systems.

31 years residential roofing contractor with 25+ licensed in California central valley

I also did ridge vents when I re-roofed.

I have considered putting an attic fan in my garage just to suck out the hot air in the evenings.  Not so much for just the attic, but for the entire garage.  This project never got any traction with my planning department.

Can you passively vent the attic and soffits?  A passive flow will work when the temp is high enough to matter.

Some people put a powered vent in their attic, which is the standard, reliable way of doing what you are talking about, but you still have to provide a route for the air to enter your attic.

The way my attic is vented, I could install a fan in areas that would increase ventilation, but I'm not sure it would be worth the extra power to do so unless I was working up there.  Here in the midwest, I'd probably accumulate too much moisture if I was actively driving air through the attic 24/7.

Anyone got a lead on a good 36" whole house fan?  Mine died.  Bearing failed and it dropped the whole blade and shaft on the louver.  That was fuckin loud.  

I'll bet.  

I'll ask my dad if he wants to sell his.  It's only 50 years old.