Whole House Fans:

Homes built after 1991 are required to have mechanical ventilation systems installed.

One such system includes a timer controlling a damper that bring in fresh air at a measured rate and introduces it into the heating system of the home. The timer activates the blower of the heating system and activates a Whole House fan at the same time.

This system is designed to introduce fresh air into the home for about 8 hours each day.

A recent study of over 450 home with this system type installed showed that more than 400 were not installed or operating properly resulting in unhealthy home environments.