They have thermostats that turn the fan on at a recommended preset temperature of 100 110 degrees.
Attic too hot.
High temperatures inside your attic shorten the life span of shingles.
Rotting visible rotting such as cracks or shrinking of the wood in the attic is a big indicator that the attic is too hot.
Alternatively install passive vents such as gable soffit and ridge vents which are openings in the roof that allow hot air to escape.
If hot air is allowed to sit in your attic it could overheat the shingles on your roof and cause damage.
In addition hot air in your attic could increase moisture levels which could result in wood rot and mold growth.
Install electric ventilators and attic fans which remove hot air from an attic.
Having a properly vented attic is the best way to keep attic cool because it allows the hot air to escape during the summer.
Too many people believe that because heat rises ventilating an attic space during the winter means you re releasing warm air and creating a drag on your heating efficiency.
A hot attic is bad for several reasons.
If these vents become clogged this can be an indicator of overheating in the attic.