Attic Fans versus Whole House Fans

[ErikWood]

Hello Gentlemen:

This is my first post and I've learn an amazing amount of information from a group of obviously well-schooled industry professionals.

Yesterday I was considered a powered attic fan. I live in Southern California near Palm Springs (the desert) where summer temps can reach 120. My house in single level, tile roof. However, evenings are often very comfortable and we can often turn off the A/C if only there was a breeze at night, which oftentimes there is not. That's why I considered the attic fan. But...

I apparently confused an attic fan with a whole house fan. Am I correct in saying that the attic fan's intended purpose is only to cool off the attic, and NOT the rest of the house (via the negative pressure)?

A great many of you say the attic fan is a waste because it pulls out conditioned air. However I haven't seen a post which talks about only using the fan when outside temps are cooler than inside temps... like at night, here in the desert. So, in this case, wouldn't the fan work as desired... helping to pull out not only hot attic air (which, I hypothesize, can radiate through the attic floor and heat the entire house), but also to pull the cooler outside air INTO the house through open windows?

Thanks so much for all your help.

Erik

[jpsmith1cm]

Erik,

started a new thread for you.

[Shophound]

Whole house fan: pressurizes the attic to draw air out of the house. Attic must have plenty of ventilation ports for the fan to work adequately. Louvers to attic from house can be very leaky, where heated air will be lost in winter and hot attic air will enter in summer when air conditioning system is running.

Attic fan: augments natural convective attic ventilation. Not a problem if ceiling below attic is airtight (which is very seldom the case) or the space below the attic is not air conditioned. However, it is not intended to ventilate a house like a whole house fan can do.

As stated above, the drawback to the whole house fan is the louvers between attic and house. And that the attic must have plenty of ventilation openings for the fan to move enough air (not a drawback in itself unless your attic currently does not have enough openings...added expense to the project). You must also be careful of any combustion appliances within the house that can backdraft while the whole house fan is in operation.

[tipsrfine]

Do some googling and you will find a lot of good stuff regarding whole house fans being used in your area. My opinion is they are a great idea if your climate supports it.

[smoke]

Additional $.02,
Attic fan's intended purpose is to draw the heat out of your attic to reduce the penetration in you conditioned space.

As mentioned above, the whole house fan in your ceiling, when turned on it will move a large volume of air from your houses conditioned space a push it through you attic.
You will need to open windows in your house during operation and during install you will have to have more ventilation added to your attic.
I wouldn't recommend them. Swamp Coolers used to be cool too but our current technology is so much better now.


You might look into thermal barriers for your roof and an attic fan. It's all about R value of your home.

[jpsmith1cm]

Cool Daddy

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