from Luke in Waukesha, WI:
#660
I installed a vent over my stove last summer. It vents outside and now the cold air is leaking in and the kitchen is cold. What is the best way to remedy this?
Replace the passive flap. Read on for more.
Typically, the flap on the termination cap on the outside acts as a passive backdraft damper. It is designed/intended to remain in the closed position until you operate the exhaust fan. When operating the fan, the force of the exhausting air causes the flap to open, allowing the exhausted air to flow to the exterior. Often, this flap does not work as intended and allows outside air to enter, especially in windy conditions/locations. Because cold air is heavier than warm air, it flows downward through the duct and enters your kitchen. For this reason, we recommend (when possible) to duct these vents down to the floor joist cavity below and out the rim joist (located above the foundation wall) as a way to reduce the effects of cold air “falling” into kitchens. The concept is that cold air does not fall up.
All of the above is assuming the existing flap is not a dedicated spring-loaded backdraft damper. A permanent fix would be to remove the passive flap and replace it with a dedicated spring-loaded backdraft damper. Prior to this fix, contact the supplier of the range hood vent to discuss how it may affect your warranty. They may have an alternative option.
Published Tuesday, January 19, 2010