Indoor air quality has become a serious issue. Most houses have very toxic air!  Ventilation is necessary.   At a minimum, a 24 hour fan must provide 20 cfm for the first bedroom and 10cfm for every bedroom after that.

Ventilators-

• Exhaust only-  A quiet low volume bath or laundry fan can provide the needed air if wired so that it can't be shut off  with a lighted indicator in place of the switch. The light tells you if the fan ever stops and needs replacement. The air supply to the home is passive with make up air coming through the minor leaks around windows and doors.

• Supply only- This is a  special fan that blows air into a home. It's exhaust is passive, again using the small leaks of the house for air to escape. It is wired like the exhaust unit.

• Heat Recovery Ventilator- Both exhaust and supply- This is the ultimate solution to indoor air quality. Both the exhaust and supply are fan driven and a heat exchanger recovers the energy in the exhaust so air exchange can be increased greatly without affecting  energy costs. Filtration and the ability to control house internal pressure make it possible to build a dust and allergen free home.