It depends on the climate and weather conditions. In a hot climate, it is recommended that the attic fan runs continuously to keep the house cool. In a cold climate, it is recommended that the attic fan runs for about 30 minutes every 2 hours to keep the house warm.

It depends on the size of the fan and your climate. In general, attic fans should run for about 15 minutes after the attic has cooled down to the ambient temperature outside. So if it's 100 degrees outside, your attic fan should run for about 15 minutes after it's cooled down to 90 degrees.