Condensation On Attic Fan Damper

If water drips from the bathroom exhaust fan the damper that normally controls the flow of air through the pipe may not be working correctly.

Condensation on attic fan damper.

It should open only under pressure from the warm air to let it out and remain closed the rest of the time. First inspect the damper on the outside. Exhaust fan condensation drip. Just as we were ready to move back in we discovered both bathroom fan exhaust ducts as well as the gas dryer duct all upstairs have been filling with condensation.

The outside damper is stuck. The duct should not be aimed at a roof vent or have any loose. Find the vent hood on your roof or exterior wall. The exhaust vent in the powder room downstairs is fine this is a new thing.

There s a damper on the fan housing too but the outside damper is much more likely to stick. If the damper won t open the fan may drive enough air through the duct to cause condensation but not enough to warm the duct and dry it out. Attic air leak into the fan unit unitself from not being well sealed to the ceiling attic floor exhaust damper not opening properly so humid exhaust air doesn t exhaust and stays in the duct getting cold enough to condense and drip back down. The duct is not kinked but there is a 1 5 inch gap between.

If your ducts are properly insulated another potential cause of condensation is lack of use. Whether you use your bath fan or not some warm air will still escape into the ducting.