Get one that runs on a temperature sensor.
Best way to lower attic temperature.
Install electric ventilators and attic fans which remove hot air from an attic.
Ideal attic temperatures shouldn t be more than 10 to 20 degrees hotter than outside temperatures.
It will help to keep the attic much cooler in the summertime.
Gable vents around 25 each plus 75 per vent for labor can lower attic temperatures about 10 degrees.
When reroofing use white or pale gray shingles instead of dark ones.
A solar powered attic fan would be best.
Also make sure your attic is ventilated.
Adding a radiant barrier to the underside of your attic structure will help reduce heat gain in the space but be sure to check your roof shingle warranty and make sure it would not be voided by such a measure.
Again i m assuming that you re not considering a sealed attic lowering the temperature of an attic that contains ducts can reduce your air conditioning costs.
They have thermostats that turn the fan on at a recommended preset temperature of 100 110 degrees.
A ridge and soffit ventilation system an extra 200 during reroofing will reduce attic temperature to around 100 degrees.
If you don t worrying about how best to keep the attic cool is a bandaid on a self inflicted wound.
In existing homes the question is important.
If your attic soars above 100 degrees and reaches the 150 mark its time to consult.
Use a thermostatically controlled roof mounted ventilator.
The thermostat will usually start at 95 degrees fahrenheit which is the temperature that the attic fan usually starts at.