Attic Fan Recommendations


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Old 04-14-16, 04:04 PM
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Attic Fan Recommendations

A few years ago the motor died in both of my attic vent fans (the type that look like a big mushroom on the roof) I replaced both with a generic motor from Lowes. Both died a year later and like an idiot I replaced them with the same motors because I was in a rush and they were right down the street. Of course, one has now died and I need a recommendation on a good brand of reliable motors that can be ordered. Thanks for any input.
 
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Old 04-14-16, 06:14 PM
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Get rid of them and install a ridge vent.
 
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Old 04-14-16, 09:55 PM
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I don't use them, but some here do so hang tight and see what we get.

My question would be, why are they failing? One concern is, a limited supply of intake air, like plenty of soffit vents. Attic fans need the air flow to limit their own heat. Tell us about the rest of the attic ventilation.

bud
 
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Old 04-15-16, 07:37 AM
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Could a lack of airflow also be cause by too much venting? Reason I ask is because I have a ridge vent and soffit vents (none of them blocked) and had an attic fan crap out after one year. The second motor I put in is on its fifth year so maybe the original motor was defective.
 
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Old 04-15-16, 07:53 AM
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I would discourage the use of a fan when ridge vents and soffit vents are used,cost me over 6K to have mold migrated from my attic as a result of having both,originally only had fans and after installing a new roof with ridge vents a soffit vents is when my mold developed,removed the fan and added more soffit venting and it's been fine.
JMO
 
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Old 04-15-16, 09:43 AM
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The house came with ample soffit vents, ridge vents, and the two fans. The soffit vents are not blocked anywhere. I guess it comes with living in Florida, but even with all that it gets really, really hot up there. Unbelievably hot. I go up there every now and then and have not seen any evidence of mold, even though it is very humid here. What happens is that they are frozen up after the winter (when they don't run). Maybe they are getting rust in there somewhere due to the humidity.
 
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Old 04-15-16, 11:22 AM
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Are you anywhere near the salt air?
If the bearings are freezing up, I would look for a motor where I could lubricate it.
I have no experience with these, but here is Graingers link with many models.

Is yours a roof or gable mounted fan?
https://www.grainger.com/category/hv...ts_optout=true

Bud
 
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Old 04-15-16, 12:07 PM
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...it gets really, really hot up there.
What is "really, really hot"? It is normal for attic temperatures to be 20 to 40 degrees warmer than the outside temperature So if your outside temperature is 100[SUP]o[/SUP] it would not be unusual to see as high as 140[SUP]o[/SUP] in the attic.

Now running an electric motor, especially one rated for "fan duty" or "air over" in a 140 degree environment IS asking quite a lot from the motor.
 
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Old 04-15-16, 02:35 PM
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I would definitely consider 140 deg. really, really hot! I don't think it's that hot, but it's in the "spend more than 15 minutes up there and you might pass out" range. The problem with getting one that can be lubricated is that I would regularly need to make it across half of the attic in a foot of insulation. I would probably end up putting my foot through the ceiling with my luck! (no floor up there) I am having some more insulation put in next Friday, so I would like to sort out the fan before they do it. Also, thanks for the link Bud!
 
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Old 04-15-16, 04:09 PM
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A raised walkway is a blessing when you have lots of insulation.

Furd is correct, that during the day while the sun is shining it is a challenge for even a fan cooled attic to control the temperature. Where I like them, been a long time, is during the evening when you can exhaust all of the hot air quickly.

That brings me to the question, why 2 fans? Is this a huge attic? A 1,500 ft² attic with an 8' peak has a volume of 6,000 ft³. double that for a 3,000 ft² home. An exhaust fan running at 2,500 cfm will make quick work of most attics. That's one fan.

If you replace the shingles, investigate their reflectivity. Some can reject a high portion of that solar energy before it heats up the roof. next would be to look at adding a foil covering directly against the bottom of the roof. Radiant energy is how that hot roof transfers most of its heat to your insulation and ceiling below.

Bud
 
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Old 04-15-16, 10:21 PM
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The house is 2400 sq. ft. plus a 2 car garage using the same attic. I'm not sure why they chose the arrangement they did when they built the house (I am not the original owner) but since I have two fans I would like to use them both. A new motor is not a huge cost, so I want to keep it going.
 
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Old 04-16-16, 07:11 AM
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If they are on switches, try running only one at a time and see if you can detect the difference. Besides using less motor energy, it will steal less ac from the house and the motors will last twice as long.

Bud
 
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Old 04-16-16, 07:56 AM
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I'm always interested in having the motors lasting longer. Unfortunately, I need to get a new one first. Today is my day to take care of it, so I will see what is available in the area and hopefully have it done tomorrow.
 
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Old 04-16-16, 08:12 AM
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Here's some reading for you. After a discussion on whole house fans he gets into attic ventilation.

http://www.greenbuildingadvisor.com/...r-do-they-hurt

Bud
 

Last edited by Bud9051; 04-16-16 at 08:14 AM. Reason: link correction
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Old 04-16-16, 12:28 PM
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Thumbs up

Thanks for the link! That looks like he took some time to research it. I wish that there were a straight answer, like "always, always use fans" or "never ever use fans". But, after reading that, I think I will just leave it as is. You saved me some money and getting really itchy from the insulation. Unless it were going to definitely save a lot of money, it's not worth it. Also, I leave the attic access in the garage open since the garage door is usually up and hot air constantly blows out when there is a breeze, so that is obviously doing something. Thanks again.
 
 

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