Astonishingly, we've only just noticed why the kitchen is so freezing cold; the extractor fan in the wall has never actually worked, so we've just got … Hi Steve, Fans normally come with a finial with fins that drop down and close the vent when the fan is turned off, depending on the type of fan it is either part of the housing, or for inline fans a separate article, it sounds as though somebody omitted fitting these, they are … Maggie Scofield is suffering from cold air that's coming down through her kitchen exhaust fan in Raleigh, NC. These thin metal flaps don’t form airtight seals because they have to open when the hood’s fan is working at low speed, but they should keep the cold drafts, and the hot ones, from coming in through your hood. When it's working properly, the exhaust duct is a one-way street to the outdoors. Is there any way to stop it, such as a valve of some kind or a different type of exterior vent? When its off with the slightest wind outside cold air comes in. Outside, at the end of the duct attached to your range hood, is a flap designed to prevent cold air from coming through the hood. Cold Air Kitchen Exhaust Fan Q & A | Ventilation text: Tim Carter. Between the two of them it does a good job of stopping massive drafts but the long run of duct and the thin metal damper doors are not insulated so even without wind you can feel some cold air falling down the duct and out of the vent. Vents ar often fitted with a draught preventer which looks like little plastic venetion blinds. I believe some fans have a type of gate inside that opens and closes mine doen't? There is very cold air coming in through the hood. 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. This will be because (1) wind direction and (2) there is not an effective control to stop air blowing in. I need to know if there is anything that can be bought to block (placed over) the vent when swiched off. When working properly, the flap should close when the vent fan is not in use, and open to let air escape when the fan is in use. The hood in the kitchen. Why Do We Need Exhaust Fans? The flaps stop the cold outside air from leaking directly into your bathroom and house. it is possible that cold air is blowing into the duct from outside. I put my hand up to the vent and didn’t feel any cold air. These … This is a substantial energy-loser that causes cold drafts to enter your bathroom and house! Many common bath exhaust fans use a single plastic flapper to attempt to reduce this air leakage. In the winter, cold air leaks in through the duct and into your bathroom, while your heated air just pours right out! Bathroom extractor works fine, when switched on, getting the air out. Is anyone aware of a fix for this? Bearing in mind it is a ceiling fan. In bathrooms and kitchens, overhead exhaust fans are used to pull unwanted airborne particles out of the room and into the atmosphere. But during the cold-weather season, exhaust fans may also make it too easy for frigid air to creep in. We're getting a lot of cold air blowing back down through the extractor and out into the kitchen. One is located just above the fan blower where it connects to the duct and the other is on the roof. I guess they are supposed to have flaps in them too. I have the GC'ers coming back on Tuesday to do a few things for me and am hoping they can address it. One is at the top of the hood, where it connects to the duct, and the other is at the wall or roof cap where the duct exhausts its air. I just walked into the bathroom to see if any cold air was leaking through the fan.