What shoud I set my Gable Fan thermostat to?

Question

I just installed a gable fan in my attic. Since I live in Sacramento, CA, where temperatures can typically reach close to 110F, what should I set the thermostat to? Is it possible that the temp in the attic could be cooler (105F) than the outside Air sometimes (108 or 110) and I could be doing more harm than good?

Thanks!

Answer 1

The attic will typically get much hotter than the outside air.  A Gable Fan will exhaust that very hot air while sucking outside air in through the vents making it easier to cool your house.  Setting the thermostat lower will make it run more often which will use more electricity.  I would follow the recommendations that came with the fan.

Answer 2

In Sacramento in Summer the attic temperature will always be hotter that the outside temperature with the exception of possibly early in the morning on a few days.  You can run that fan anytime without worry of doing more harm than good.

It is not good to run the fan 24 hours a day however.  The fan uses electricity.  If the temperature difference between the attic and the outside is not greater than about 30 degrees it is not really cost effective to run the fan.  If you set the stat for about 20 to 25 degrees higher than your indoor temperature set point you should be about right.

I worked the first 15 years I did contracting in Sacramento and have been in a bunch of attics in Sacramento in the summer at all different hours of the day.  I know from personal experience that what I an telling you is correct.