Condensation On Attic Fan Damper

Bath fans have a damper designed to keep the outside air from entering in through the fan but that valve doesn t stop warm air from escaping.

Condensation on attic fan damper.

Find the vent hood on your roof or exterior wall. Exhaust fan condensation drip. The damper will help prevent cold air from dumping back down into the house which may lead to condensation right at the fan itself. It should open only under pressure from the warm air to let it out and remain closed the rest of the time.

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. 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. 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. First inspect the damper on the outside. Whether you use your bath fan or not some warm air will still escape into the ducting. The duct should not be aimed at a roof vent or have any loose.

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. If your ducts are properly insulated another potential cause of condensation is lack of use.