Cold Air Kitchen Exhaust Fan

Maggie Scofield is suffering from cold air that's coming down through her kitchen exhaust fan in Raleigh, NC. Allow her to give you a full report:

"It's been frigid here in NC yesterday, and expected to get down to 0 degrees over the next few days. I never noticed before, but there is a very cold downdraft from the exhaust opening over the stove, where the vent fan is installed.

What can I do to stop this downdraft? It would be great if the fan had a damper like our fireplace does, but it doesn't, and unfortunately the chasework for the fan goes straight through the stick-built cabinets that are above it.

I thought about just putting some aluminum foil over it to stop the air. Is that silly? Here's a photo of where the air is leaking."

You can see the vent opening above the stove. It's not going to be easy to seal this off. Photo credit: Maggie Scofield

Maggie, this is a common problem. Believe it or not, there's probably a damper at the end of the exhaust cap where it exits the house. Unfortunately, they don't fit too tight because they need to swing open when the fan comes on.

Add to this that the dampers can get stuck in the open, or slightly open position, over time with a buildup of condensed cooking grease.

Instead of using aluminum foil, I'd recommend an old dishtowel that you hold in place with strips of hook and loop material. You can now buy this in all sorts of configurations including clamps. In your case, you may need to epoxy the hook part to the sides of the filter box and then sew the loop part to the dishtowel.

The advantage of this method is you can then wash the dishtowel as required so it looks nice and clean as it will get pretty gross unless you clean the underside of the hood on a regular basis. We don't here at my house because it's such a miserable job.

You'll need to cut the dishtowel so it doesn't block the light in the hood. If you cover that light up with the towel and someone turns on the light, it could overheat and cause a fire.

The other option, and I don't like this one too much because you can't see it, it to stuff a rag up under the filter cover. This rag plugs up the exhaust pipe completely. Once again, this is a fire hazard in case someone turns on the exhaust fan FORGETTING about the rag. The fan can overheat and cause a fire.

If you decide to do this, then come up with a reminder tag similar to what the US Navy and Air Force use on parts and munitions attached to planes. They say: REMOVE BEFORE FLIGHT.  In your case, it needs to hang down over the stove and say: REMOVE RAG BEFORE FOOD.