Attic ventilation


  #1  
Old 06-12-15, 08:01 PM
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Attic ventilation

I have three roof mounted powered vent fans. Two motors went bad on the same day? I removed the motors and found they were not burned and no smell.
They had an external mounted capacitor so I removed the known good one, and neither would run.
Now, I am faced with buying three motors (might as well replace all). Cost will be close to $200.00.
I am beginning to wonder if it is worth the cost. A few years ago, in another home, I replaced the roofing in which there were no vents in the attic. A roofer advised me to just put three "Pancakes" for vents. He also said he did not recommend the turbines because they have cheap bearings and would spin while setting in grass or on driveway!
Just wish I could find an actual comparison test as to how efficient each type ventilator is.
 
  #2  
Old 06-12-15, 08:39 PM
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In a southern climate owners often try to cool the house by ventilating the attic. But tests have shown that air sealing between the house and the attic plus lots of insulation and good passive venting will do the job without the electrical cost and maintenance. We can discuss going that direction if you wish.

As for powered vents, especially 3 of them, they depressurize the attic and draw that expensive air conditioned air right out of the house. So even if you stay with the powered fans, you should do a class A job of air sealing. Related link below.

So, essentially, you will have to do the air sealing either way so considering the passive vent approach may be the better option.

What other vents do you currently have in addition to the 3 powered vents? Looking for ridge, gable, soffit, or other roof vents.

http://www.efficiencyvermont.com/ste...ide_062507.pdf

Bud
 
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Old 06-12-15, 08:48 PM
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Vinyl Soffit vents all around. No ridge vent in app. 3,000sf one story home with unfinished partial basement. Thirty year old brick house that is super insulated with large shade trees all around.
 
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Old 06-12-15, 08:55 PM
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To go passive venting you would need a ridge vent or gable vents if you have gables. Those powered vent openings could possibly be filled with roof vents.

Do you run the air conditioning?
Have you had an energy audit where they measure the air leakage?
If you look at the basement ceiling around plumbing pipes and your chimney if you have one, it will be obvious if someone has done a lot of air sealing. All penetrations, electrical should have been sealed in some manner. Same goes for the attic, now buried in insulation.

Bud
 
  #5  
Old 06-13-15, 05:29 AM
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100% sure there's not just plywood under those vinyl soffit vents, and they just covered it up?
100% sure the soffit vents are not covered up with insulation?
No way two fan motors failed on the same day, I be checking all the elect. connections.
 
  #6  
Old 06-13-15, 05:36 AM
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What did the guy mean when he said turbines have cheap bearing and will turn on the grass or driveway? Is that supposed to imply they turn very easily with very little wind? That is exactly what you want. I am a big fan of turbines as most times people do not get nearly enough vents at the top of their roof. Yes the bearings wear out after several Years, but they are very easy to change out when they wear out.
 
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Old 06-13-15, 09:43 AM
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Turbines turning on the ground means the wind is blowing. Most people think the heat escaping from the attic turns the fans.
I have had to replace several bearings (plastic bushings) in my older homes have no idea how old they were.
 
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Old 06-13-15, 10:22 AM
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This is what I mean. A turbine works by having the wind blow and turn the turbine, sucking air out of the attic at the top and drawing it in at the bottom.

The fact that they turn while on the ground when the wind blows (as they should) is irrelivent to their effectiveness.
 
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Old 06-13-15, 12:49 PM
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I am not in disagreement with you, just stating what a 70 year old professional roofer told me.
 
  #10  
Old 06-13-15, 01:54 PM
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I understand. I know alot of those "professionals". Lol.
 
 

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