What are your Thoughts / Opinions / Advice on Attic Fans
Joshua D.Pro Member
BiggerPockets Founder · HI · Member since 2008 · 16k+ posts · 5k+ votesWhat are your Thoughts / Opinions / Advice on Attic Fans
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Real Estate Investor · Pomona, CA · Member since 2009 · 56 posts · 25 votes
16yThe concern is not the fan catching the house on fire.
The concern is if there was a fire, the heat from the fire would turn on the fan causing air to circulate bringing fresh oxygen to the fire and increasing the intensity.
I do not know if this would happen but that is how it has been explained to me.
29 Replies
- Flipper · Phoenix, AZ · Member since 2009 · 973 posts · 679 votes16y
I'm not an expert by any means, but I wouldn't see any properly installed, UL listed, electrical device as a fire hazard.
That said, if the attic space was designed to have a fan, you're probably not getting all the airflow needed. As for the noise, I wouldn't think it'd be a problem if your attic is properly insulated.
- Lien Investor · Riverside, CA · Member since 2010 · 43 posts · 6 votes16y
Joshua,
Attic fans are simply a fan with a thermostat that cycles it on when the attic temperature reaches a specified temperature. To blow the hot air out of a vent from the attic. By pulling the hot air out of the attic, they help to keep the home cooler. I grew up in a two story home with one. As long as it is installed correctly, and maintenanced every year or so to make sure the wires aren't bare and the fan is functioning properly there should be no problem. If used properly it can help cut down on a/c costs.
:) - Investor, Entrepreneur, Educator · Springfield, MO · Member since 2009 · 21k+ posts · 12k+ votes16y
Josh, never heard of an attic fan causing a fire, I'm sure it has happened, but what's the chance there? I have them, it's about 82 outside, the attic fan is running and the air is set at 76 and it hasn't kicked on. They work....seems like they are low voltage/amp motors, I don't worry about them at all, at least I hadn't until you mentioned it! LOL,
- Real Estate Investor · Pomona, CA · Member since 2009 · 56 posts · 25 votes16y
The concern is not the fan catching the house on fire.
The concern is if there was a fire, the heat from the fire would turn on the fan causing air to circulate bringing fresh oxygen to the fire and increasing the intensity.
I do not know if this would happen but that is how it has been explained to me. - Investor, Entrepreneur, Educator · Springfield, MO · Member since 2009 · 21k+ posts · 12k+ votes16y
Hey William, there is my vote! Very good point, never gave that much thought! I wonder if there are models with a shut-off if the heat reaches, say 150 degrees?
- Landlord · Seattle, WA · Member since 2010 · 3k+ posts · 1k+ votes16y
Glad, I read this. I hadn't thought about attic fans spreading a fire, but this does seem like a serious concern. There must be some kind of safeguards that can be used though to prevent this situation. Worth looking into to.
- 16yMark UpdegraffBusiness MemberReal Estate Broker · Rochester, NY · Member since 2010 · 1k+ posts · 697 votes
Not sure what kind of "attic fan" you're all referring to. One that goes in a window?
On my house growing up we had an "attic fan" - it is installed in the ceiling of the hallway upstairs. It is NOT on a thermostat. It has a low / med / high setting. In the summer, our attic windows are open, and the the fan is on, it pulls air from the downstairs / basement up through the house. The hotter air gets pushed out the attic windows. It works great! We never had AC or central air, and were never too hot while sleeping. On High, it is noisy, but the temperature decrease is worth it and I've had not problems sleeping :D
Updegraff Group Realty4.746 Reviews - Boston, MA · Member since 2008 · 149 posts · 57 votes16y
I have one, it pushes air out the middle of the roof and draws it in through the vents at either end. I'm not sure how big of a difference it makes to be honest. When I first moved in the thing never turned on, so I set it really low, but with the heat we've had it runs all day and night, which defeats the purpose I think (air is too hot so it just runs).
I thought my fan had 2 dials on it, one for temperature and maybe the other was humidity.
Regarding the fire issue, if there is a fire in my attic I'm not going to notice until it gets lower in the house, and by then there is ridiculous damage to the house anyway.
- SFR Investor · Orange County, CA · Member since 2009 · 1k+ posts · 1k+ votes16y
Originally posted by Mark Claire:
On my house growing up we had an "attic fan" - it is installed in the ceiling of the hallway upstairs. It is NOT on a thermostat. It has a low / med / high setting.
That's what we have, but the correct term is "whole house fan". An "attic fan" sits between the attic and the outside. From what I can gather, the name is properly derived from which space is getting ventilated, not necessarily where the thing is actually located. :cool:Then again, as I think about it, if you leave a WHF on long enough, it will ventilate the attic as well, i.e., all that air coming into the attic from the house has to go somewhere. That's why I added another gable vent to our house... having enough exhaust area is just as important as opening enough inlets below.
- BiggerPockets Founder · HI · Member since 2008 · 16k+ posts · 5k+ votes16y
NOTE: I'm not referring to a whole house fan, but an attic fan designed to cool the attic.
- Attorney · Raleigh, NC · Member since 2008 · 4k+ posts · 1k+ votes16y
Josh,
You can get a solar powered attic fan I believe. Being solar powered, it's a low voltage system and as likely to start a fire as a doorbell.My concern is that if you purchased the property and there was an attic fan, there probably was a reason. The attic fan is there for both cooling and ventilation. Cooling is just the most perceptible effect of the ventilation. The cooling keeps your roof shingles from heat damage and premature failure. The ventilation keeps condensation from forming and creating or contributing to mold. I've seen moisture in attics so bad the mold ate through 2x8 rafters. In the winter, ventilation helps counteract ice damming. It's just an all around good thing.
This is something I would take care of this year (wait till fall probably - it's way to friggin' hot for this crap right now). Check out that solar unit though and see if that will work for you and if it's cost effective.
I've never had an attic fan start a fire and I've seen way too much damage from the effects of one not working. My 2 cents....
Tim
- Attorney · Raleigh, NC · Member since 2008 · 4k+ posts · 1k+ votes16y
Originally posted by William Johnson:
The concern is if there was a fire, the heat from the fire would turn on the fan causing air to circulate bringing fresh oxygen to the fire and increasing the intensity.
Wouldn't be an issue unless it was an attic fire in which case you've probably got asphalt shingles on fire....which is like burning oil...so you're already screwed. - Real Estate Investor · NC · Member since 2010 · 7 posts · 0 votes16y
I got a chance to talk to my roofer today. He's been roofing 40 years. His thoughts are if you have a ridge vent and ample soffit ventilation you are fine. If you have no ridge vent and soffit vents you need an attic fan as long as you have gable vents. He says that what the industry standards say.
- Attorney · Raleigh, NC · Member since 2008 · 4k+ posts · 1k+ votes16y
Originally posted by Tony Deese:
I got a chance to talk to my roofer today. He's been roofing 40 years. His thoughts are if you have a ridge vent and ample soffit ventilation you are fine. If you have no ridge vent and soffit vents you need an attic fan as long as you have gable vents. He says that what the industry standards say.
This will work on gable roofs just fine. Just make sure your insulation contractors don't back the perimeter of the attic with insulation and block the air flow. If they do blown in, they're supposed to put in foam channels to allow free air flow.I have seen problems on hip roofs where there's plenty of soffit for a free flow of air, but not enough ridge. This is especially the case in areas where it gets hot and you have asphalt shingles on massive roofs with huge rafter lengths on steep slopes leading up to little ridge vents. They act like a percolator. (bonus points if you start dancing here and saying, "It's time for the percolator"). The roofs that have this problem look like their shingles are curling faster halfway up the roof. Something like this could benefit from some other ventilation to supplement it.
- Real Estate Investor · NC · Member since 2010 · 7 posts · 0 votes16y
Tim is correct on this! The only true hip roof I've owned burned in 07. Not an attic fan. I own three others that are what are hips on three and a half sides.With a gable on half of the front. There's not much ridge vent available. I put attic fans in them. Good call!
- Real Estate Investor · Portage, MI · Member since 2010 · 470 posts · 315 votes16y
Originally posted by Tim Wieneke:
Originally posted by Tony Deese:
I got a chance to talk to my roofer today. He's been roofing 40 years. His thoughts are if you have a ridge vent and ample soffit ventilation you are fine. If you have no ridge vent and soffit vents you need an attic fan as long as you have gable vents. He says that what the industry standards say.
This will work on gable roofs just fine. Just make sure your insulation contractors don't back the perimeter of the attic with insulation and block the air flow. If they do blown in, they're supposed to put in foam channels to allow free air flow.
I have seen problems on hip roofs where there's plenty of soffit for a free flow of air, but not enough ridge. This is especially the case in areas where it gets hot and you have asphalt shingles on massive roofs with huge rafter lengths on steep slopes leading up to little ridge vents. They act like a percolator. (bonus points if you start dancing here and saying, "It's time for the percolator"). The roofs that have this problem look like their shingles are curling faster halfway up the roof. Something like this could benefit from some other ventilation to supplement it.
Tim,
You may also have some "pot vents" installed on the hip roofs. You are correct on the heat build up and shingle curl. That cuts the shingle life big time! It also adds to cooling costs in the summer.Josh,
I'd think about having a competent roofer (get a couple of opinions, since all roofers are not created equal!) check out your existing roof venting. I would say that in about 95% of the instances, you can fix the problem without the attic fan. Have your insulation checked, too. As Tim said, the baffles may be covered (or missing) if insulation was added. I would also suggest maybe adding insulation. As a Certified Green Professional builder, I'd rather see a properly vented roof system and lots of insulation, rather than an attic fan trying to mitigate those shortfalls.
Bill
- Real Estate Investor · Portage, MI · Member since 2010 · 470 posts · 315 votes16y
Originally posted by Tim Wieneke:
Originally posted by Tony Deese:
I got a chance to talk to my roofer today. He's been roofing 40 years. His thoughts are if you have a ridge vent and ample soffit ventilation you are fine. If you have no ridge vent and soffit vents you need an attic fan as long as you have gable vents. He says that what the industry standards say.
This will work on gable roofs just fine. Just make sure your insulation contractors don't back the perimeter of the attic with insulation and block the air flow. If they do blown in, they're supposed to put in foam channels to allow free air flow.
I have seen problems on hip roofs where there's plenty of soffit for a free flow of air, but not enough ridge. This is especially the case in areas where it gets hot and you have asphalt shingles on massive roofs with huge rafter lengths on steep slopes leading up to little ridge vents. They act like a percolator. (bonus points if you start dancing here and saying, "It's time for the percolator"). The roofs that have this problem look like their shingles are curling faster halfway up the roof. Something like this could benefit from some other ventilation to supplement it.
Tim,
You may also have some "pot vents" installed on the hip roofs. You are correct on the heat build up and shingle curl. That cuts the shingle life big time! It also adds to cooling costs in the summer.Josh,
I'd think about having a competent roofer (get a couple of opinions, since all roofers are not created equal!) check out your existing roof venting. I would say that in about 95% of the instances, you can fix the problem without the attic fan. Have your insulation checked, too. As Tim said, the baffles may be covered (or missing) if insulation was added. I would also suggest maybe adding insulation. As a Certified Green Professional builder, I'd rather see a properly vented roof system and lots of insulation, rather than an attic fan trying to mitigate those shortfalls.
Bill
- BiggerPockets Founder · HI · Member since 2008 · 16k+ posts · 5k+ votes16y
Just got my attic fan installed and it is working wonders! The attic is a good 20+ degrees cooler now!. I've got to replace some soffit vents, but otherwise we're in business.
Just thought I'd share the update!
- Dallas, TX · Member since 2010 · 56 posts · 2 votes16y
Full disclosure: I only read the first 2 posts, there are a lot of replies and your problem is already solved so no reason to read them all.
I can say, though, that this is somewhat of an area of expertise for me because I am a residential energy efficiency professional here in Dallas.
That being said, here is what happens with those AC powered electric fans in Texas - your region may be different, we have extreme heat around here!
The reason that your fan broke is because almost all AC electric fan motors break after a few years (5 - 6 years average here in Texas). They do have a thermal snap switch to turns the fan on at 90 or 95 degrees, and shuts off when the temp gets below that, but here in Texas your attic is about 120 - 130 F for 3 or 4 months straight, so the fans never shut off. This is what causes the motors to break - they are just over worked.
Furthermore, the electricity that it takes to run the fan exceeds the energy that you save from cooling the attic - again, regional differences may occur, but this is at least true in the south - see this study done in Florida:
http://www.fsec.ucf.edu/en/publications/html/FSEC-GP-171-00/You do get benefit of reducing strain on the HVAC system and ductwork if it is in the attic, so even though you are spending more on electricity, reducing the temperature in your attic is important because this will increase the longevity of your HVAC system (if it is in the attic).
So, the conclusion is that for energy savings, solar powered attic fans are superior. If you go buy a fan at Costco or Home Depot or where ever, the DC electric motor will have the same problem - it will be broken after 5 or 6 years (at least in the south).
My company sells Attic Breeze solar attic fans. I am not employed by this manufacturer, and I do not receive any payment / commission directly from them. Attic Breeze is manufactured in Texas (outside Houston I think?) and they make the best solar attic fan on the market. It pushes almost twice as much air by CFM than other fans (solar or AC electric), and it comes with a lifetime warranty. They are larger and quieter than most fans, and you do pay a premium for the quality that you receive - but you will never have to replace it again.
http://www.atticbreeze.net/
If you are looking for an attic fan for your homestead, then I recommend Attic Breeze, hands down no contest. For rental, flip, or other investment properties, you may have to consider the extra cost that you would pay to get it.
- Dallas, TX · Member since 2010 · 56 posts · 2 votes16y
Originally posted by Tony Deese:
I got a chance to talk to my roofer today. He's been roofing 40 years. His thoughts are if you have a ridge vent and ample soffit ventilation you are fine. If you have no ridge vent and soffit vents you need an attic fan as long as you have gable vents. He says that what the industry standards say.
This is also quite accurate - if you have well designed passive ventilation (soffits, air hawks, ridge vents, whirly birds, etc) then you do not need active (powered) ventilation at all.Very few attics are designed with proper passive ventilation, though. And when I say very few, I mean perhaps a dozen of the 300+ homes that I have conducted energy audits for in the last 2 years have had well designed passive ventilation.
- Investor, Entrepreneur, Educator · Springfield, MO · Member since 2009 · 21k+ posts · 12k+ votes16y
Well Travis, sounds to me like business should be pretty good for you. You should be selling twice as many fans in Texas to be installed in the first place, put one row on a timer so they only work half a day, then use the second row, they should work twice as long. This will allow the price to increase over a longer period of time when they do need to be replaced and you'll be selling twice as many fans at a higher price! lol
- Homeowner · Dalton, GA · Member since 2010 · 108 posts · 13 votes16y
Originally posted by Joshua Dorkin:
NOTE: I'm not referring to a whole house fan, but an attic fan designed to cool the attic.
from when i was building houses a properly installed cutting and capping a ridge vent is better by natural convection (as heat rises) from the Eaves of your roof with adequate soffit ventilation and close off the gable vents and this will increase life of shingles - Investor, Entrepreneur, Educator · Springfield, MO · Member since 2009 · 21k+ posts · 12k+ votes16y
Originally posted by Sammy Johnson:
Originally posted by Joshua Dorkin:
NOTE: I'm not referring to a whole house fan, but an attic fan designed to cool the attic.
from when i was building houses a properly installed cutting and capping a ridge vent is better by natural convection (as heat rises) from the Eaves of your roof with adequate soffit ventilation and close off the gable vents and this will increase life of shingles
I prefer a continuous ridge vent as well, did that last year with a metal roof at the cabin, made a big difference. - BiggerPockets Founder · HI · Member since 2008 · 16k+ posts · 5k+ votes16y
Travis -
The fan stopped working because the soffit vents were somewhat blocked by insulation installed by the weekend warrior that we bought the house from.As for conclusions about the effectiveness of these fans, I can say without a doubt that we'll recover the cost of the fan very quickly. Our home is about 10 degrees cooler on average since installing the fan. We've been enduring some stifling heat here, and prior to the fan, even with our swamp cooler running, the house was very hot. With the fan we're pretty comfortable all the time.
Maybe we're the exception, but I think our attic fan is one of the best investments we've made in a long time!
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