Attic Fan vs. Power Roof Ventilator

[<fgravelle]

If you had your choice, what would you have installed in your home: an attic fan or a power roof ventilator? What are the pros and cons of each.

Thanks!

[jagerEd]

If you have refrigeration AC studies at the National Institute Of Standards and Technology have shown the powered attic fans are not cost effective. While it is true that reduce attic temperature, and the does indeed reduce the load on the AC, the cost of running the fan outweighs the cost of save energe at the AC on an annual basis. Besides, if you use one big enough to have a significant effect the noise is significant. Your neighbor will hate you.

Ed Sowell.

[Joseph Meehan]

I will answer the question assuming that the "attic fan" you are talking about is for ventilation the attic, not a whole house fan.

I have to agree with Ed. Don't bother with the power. In fact I would not bother with those wind powered roof ventilators. People seem to have a lot of problems with them, while a well designed and sized passive vent system does a good job with a much higher reliability.

Spend you money on better insulation on the attic floor.

[TURTLE]

This is Turtle.

Get you a motor powered attic vent-o-lator. the cost is nothing up against a $600.00 electric bill in the hot summer. In cooler climate like the northern state it may be a little cost effective but anywhere in the southern states where you see it get HOT these fans save a bundle down here. When i'm running a Manual J on the cooling load of a home. If i see the customer had a motorized vent fan. I will program the home as being in the shade most of the day even when it is not. This will make the size of the cooling unit to be just a hair smaller to do the same job.

Weither you need one or not really is what part of the country you live in. All the test that are run on these fans are run on homes in the northern states where they call hot as 90ºF and down south we call hot 110ºF to 120ºF . Down south the attics will get up to 140ºF to 155ºF with just draft vents and cost you big time. The Sun is what will bring the attic above the temperature outside and if your house is shaded, you may not need motorized vent fans but if your house is out in the hot sun all day. You better get you a motorized vent fan.

TURTLE

[jagerEd]

Correct. Whole house fans, which draw outside air through the house and out the attic, can be cost effective. However, some point out that dust can be a problem.

Ed