Shutters closing while running
The shutters should be gravity closed, which means they are counter weighted just enough to close with no air flow... when the fan starts, it will create a slight pressure differential across the shutters - when that pressure overcomes the counter weight, the shutters should open... I assume you open windows and/or doors when the fan runs...
I would check for the following items:
a) (unlikely) check to see if the counter weight is adjustable, if so, it may be slipping and needs reset.. I think this is unlikely as I think most shutters do not have adjustable counter weights -- check last)
b) check your attic vents to the outside -- the air being blown into the attic must escape to the outside world, otherwise it will build up pressure and the airflow will drop or stop altogether -- this sounds like what is occurring, at slow speeds, there is insufficient airflow to open the dampers, at high speeds, they open long enough for the pressure to build up and then they close as the air flow diminishes
c) have you replaced windows, caulked up windows, made any modifications to reduce the flow of air into the living areas -- air must enter the house just as air must leave the attic (assumes you don't open windows or doors)
d) if you have a fireplace, check to make sure some animal or other hasn't plugged up the chimney -- if the house is tight, the attic fan will pull air from the chimney unless it is blocked
hope this helps...
Jul 25, 2008 |
Ventamatic Direct Drive Whole House Fan...