Are attic fans worth it?


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Old 08-23-23, 11:20 AM
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Are attic fans worth it?

I live in Southern Nevada where temperatures can get very hot and even cold. Would it be worth installing attic fans? My home is two stories, 3,600 sq feet and the upstairs does get 3-4 degrees F hotter during summer.
 
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Old 08-23-23, 11:40 AM
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Most homes are constructed so the attic is not conditioned. All the insulation is on the floor of the attic to separate the comfy part of the house from the blazing hot attic. Cooling the attic with better ventilation can help but it doesn't gain you much. How much depends on the amount of insulation you have. If you have poor insulation the attic isn't as well separated from the air conditioned space so cooling the attic can help more. The better insulated your attic is the less affect ventilating the attic will have on your AC bill.

The big benefit to ventilating the attic and why ventilation is required by code is to help keep the shingles cool. Super hot shingles don't live as long as ones kept cooler.
 
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Old 08-23-23, 12:36 PM
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I agree with what Pilot Dane said in the above post, and in particular that 'cooling the attic with better ventilation can help but it doesn't gain you much'.
 
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Old 08-23-23, 01:28 PM
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Thanks for the advice. I'll move on.
 
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Old 08-23-23, 02:10 PM
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There are two types of attic ventilators.

I have a split level home. I have a mushroom fan on the high roof and a wall mount fan in the side wall on the opposite side of the house in the lower attic. The attics are connected. The mushroom fan keeps the entire attic at outside ambient temperatures.

The sidewall fan is a 36" belt driven fan. I can use it to draw air thru the house on cool nights.
I've been using it for the last several nights. I've added a motor kit to the louver so that it will open if the attic gets too hot allowing extra air into the attic.

I am 100% for any powered attic ventilation.
 
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Old 08-23-23, 07:02 PM
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Not sure if you've looked into whole house fans. I installed one of those Mr Cool fans for the night time air. My house starts out at least 10 cooler in the morning if I use it. I have similar weather to you (maybe not as cold during the winter). Anecdotally, my AC starts about 2-3 hours later than before I installed it.
 
 

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