Attic Fan

Good write up. One more thing that would make this article even better would be to talk about how much electricity it would take to cool the attic and if that would still save money because the AC won't have to run so much.

Do they make replacement motors for the electric powered attic fans? Mine went out and I can't say that I'm overjoyed with the prospect of changing out the entire unit.

Tim. I had a new roof put on last year and had the wind turbine type attic fans removed - I had ridge vents placed in lieu of the turbines. Do the ridge vents do any good. Oh yes, I live in Texas. Thanks.

Tim

Good article on attic fans. Your caution regarding the extended use of AC because of attic fans is very important to remember.
And like Ralph who writes above, i to find the
moving boxes very annoying. please stop that.
thank you
nitto

Roof mounted fans seems to be the subject of this topic, but I wonder about the effectiveness of gable mounted fans. Are they more or less efficient than roof mounts?

My attic fan just stopped working after thirteen years of thermostatically controlled ventilation, and after calling numerous electricians for a replacement, I was informed by one that replacing the attic fan when my roof has soffit under the edges of the front and back edges of the roof, side, trianglular gable ventilation, and a ridge vent that runs the length of the roof is of no cooling/energy value. I read your entire article and comments, but I am still confused as to whether I should just check the insulation depth and not replace the attic fan as natural air flow is the best or replace the attic fan for some help in energy savings. I do have a centrally air conditioned two story with basement home in the Washington, DC area(Fairfax VA).

i live near the ocean in Miami. i was considering the powered roof ventilators for a 1500 SF house to lessen the heat load on my central AC system. there is a product that moves 1050 CFM but i'm concerned about the 200 watt 1/10th HP motor(2.8 amps) constantly running. do you feel it would be cost efficient and help cooling inside? has sucking to much outside air through the attic ever been a problem? (moisture)? thanks,
Keith

Thanks Tim for this article. It has caused me to rethink the use of my household elestic powered attic fan.I live on the Canadian praries where we have very hot days but tend to have cool nightime temperatures. After reading your comment regarding the amount of air required to handle the daytime heat load I have decided to turn the fan off in the daytime and put it on auto in the evening.
I have just had the motor replaced after 15 years of use. It was running fine but I have heard stories of roof fires being caused by overheated roof fan motors.
Terry

We purchased a 2 story house containing approx. 4,200 sq feet with a 3 car garage. The house had two (2) attic exhaust ventilator fans on the top rear roof but neither worked. I asked a contractor to replace the thermostats and he did. He said that he first bypassed the thermostats to see if the motors ran and they reportedly did. After installing the new thermostats and setting them to kick on at 100 degrees F, they haven't come on.
another contractor later put on new and stronger AMP thermostats and the fan motors still won't come on.

any suggestions as to what I should do?

Thermostatic controlled attic fans can make a big difference in your monthly A/C bill. I have two (2) in my attic. Here in Texas with 100 plus degree days, they are worth the price. Important however is you must have vents under the eves of the house all the way around for the fans to pull in outside air. Minimum three vents per side. Attic ventilation is very important no matter where you live. Those vents need to be flushed out several times a year with a water hose to wash out the dirt that will clog the screens. The motors are easy to replace. You can find them on-line and at Lowes and some hardware stores. They run about $50.00. In answer to Richards problem with the fans not coming on after having the thermostats replaced; the guy who did it wired them wrong. It's not that difficult. The incoming hot wire is connected to one side of the thermostat. The hot wire from the motor is connected to the other side of the thermostat. The neutral wires are connected together. Thats it. Also, set at 100 degrees is to high. Set them at 80. You want a good jump on the heat of the day. Hope this helps everyone.

What about the formula for air intake vents square inches versus exhaust volume?
If there is inadequate soffit and gable air intake can exhaust fans and vents work effectively?

An excellent and well-written column. My only question is that, throughout the whole column, you never specify whether you are examining these various attic fans as replacements for natural attic ventilation or as augmentations to natural ventilation. I gather, reading between the lines, that you are describing attics without ridge vents - is this accurate? I am building a 2000K sqft 1-story house in upstate SC. I have read that continuous soffit-to-ridge vents running the whole perimeter of your eaves and the whole length of your ridge can supercede the need for mechanical ventilation, whether solar or electric or windpowered. Would you agree, or do you feel that, even with such vents in place, the cost of additional fan installation is worth it?

I have a 1980's home, one-story w. crawlspace, and an attic fan with gable vents. The fan died a few years ago, but I can't say that it made any noticeable difference in the power bills, thus probably not much difference in temp reduction. So, given the cost of replacement I have decided to just wait until an upcoming roof replacement and just remove the fan and seal/roof over the hole. With just two gable vents, I am debating the merits of going with a ridge vent (need to install soffit vents) or trying a reflective insulation system to keep the heat out of the attic rather than try to remove it once it's in. Any thoughts about pitfalls?

I live in the deep south and just had wind turbines installed on my roof and have seen a big difference in the inside temps. The slightest breeze will have them twirling like crazy. And my AC no longer runs constantly during the day.

Phil
I had two (2) different contractors install two different new thermostats on my attic exhaust ventilator fans and neither was able to get them running. The last or second contractor concluded that a surge must have burned out both motors.

Since we recently had a new roof put on after a complete tear off of the old, I don't want that new roof disturbed by ripping out the entire attic exhaust fans and replacing them with new units. Instead I would rather see new motors installed (assuming that can be done from the inside of the attic).

What a pity the roofing contractor told me that he didn't think the old fans needed replacement at the time he put on a new roof because he said they looked fairly new or recent ones.

Thanks for your advice. Much appreciated.

Seems like just too big a task for my area where the past 12 days it has been around 104 to 107 outside. Must be 108 in the attic. I have soffit vents every 6 feet and I open the attic door in the garage and the garage door with the wind out of the south blasting in and that seems to help some. I don't know I may be biting off my nose to spite my face!

Above is suppose to be 180 not 108!!!

I live in San Diego, California. It sounds like electric attic fans are the way to go. Can you recommend the best brand of fan to use in this part of the country?

My husband has "jury rigged" a large box fan on it's side wedged into the square entry (closet ceiling)to the small attic space in our townhouse condominium. He draws in the "hot" air up into the attic. Hmmm. Is it a bad thing to do? And can there be a fire from this? And will it trap dirt and catch fire, etc.
Thanks so much.

Hi, the article is very good. Now I understand why we have these things. Last night one of our electric attic vents started this whining noise. It sounds like the fan may need to be greased. Is this a common problem and how do I do this?
Thanks!

I have a new question. Shingles do get
very hot especially in Texas in the summer. Why use a product to roof a house that will transmit so much heat?

Is there a roofing product that is cool and reflecting neat instead of producing more heat?

I enjoy your comments very much.

Thank you, Marlys Kosel

We live in northern Michigan, and it is nothing to get 2'-3' of snow on our roof. Here's our problem: we live in a manufactured home with cathedral ceilings and a 3-12 pitch so there is virtually no attic space. But we do have 12" of pink insulation. In the winter months we get severe ice damming, which causes water to leak into the house. The roof is only 5 years old, and we had one row of rubber ice guard installed at that time. We have a ridge vent with soffits all around the house. What can we do to get some proper venting into our attic? And, prevent ice damming. I just hate getting up on the roof and shoveling it each time it snows, not to mention the fact that I'm 66 years old!