cold draft coming in through Hood Vent... any ideas why???

15 years ago

There is very cold air coming in through the hood. Is anyone aware of a fix for this? I have the GC'ers coming back on Tuesday to do a few things for me and am hoping they can address it.

It has been SO cold here in New England these last couple of weeks so this draft is very noticeable and something I want to fix ASAP.

Thank You!!

Featured Answer

davidro1

15 years ago

This is a common problem with all vent holes and fireplaces and it will be solved later this century. In terms of whole-house HVAC, these holes need to be dealt with and they aren't yet. My take on the problem. (I live in a cold climate.) Houses are more and more airtight, which is Step One towards optimal insulation against extreme cold (or heat). Then each vent hole becomes comparatively more of a problem. I think each opening should have two flappers, one at each end of the hole (i.e. outdoors and indoors). A single flapper is extremely leaky when air pressure ("wind") is pushing against it. Two thingies makes for more reasonable air pressure on the second one, less leak. Sounds like basic common sense to me, but no-one has ever integrated it into their product design or "standard" construction process. It's a recurring need in millions of buildings every year and everybody always makes it look like "'golly, we just noticed this." In buildings big and small.

So you are not alone.

-david

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Comments (10)

Jean Farrell
15 years ago
I was going to post the exact same question. We complained about it to my GC, and they did something that made it a little better, but there is still a huge draft, and I really need to fix it as well.
redroze
15 years ago
Gosh, we have the same problem. Our range hood is on an exterior wall, and he basically drilled a big hole in the wall to the outside with a thin metal round "flap" that keeps animals from coming in. I wondered how effective this was for keeping out the cold, given the wind makes the metal piece flap sometimes. I also noticed that our dishes (in cabinets on the same wall as the range hood) feel quite cold, which has me concerned.

Anyone out there, please help!
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The duct size is determined by the manufacturer of the specific unit you select but it is likely to be 8" round which will fit in a 12" dropped ceiling or soffit. A round duct is cheaper and more efficient but in such a short run you could use a rectangular duct to raise the soffit/ceiling a bit. The duct could rise vertically in cabinets and then run horizontally to the outside wall. Your kitchen designer can easily accommodate that standard detail. I've never seen a range exhaust duct installed in a wall. I can think of no reason for a remote blower unless the sound of the fan at the highest speed (rarely used except when something is burned) is seriously objectionable. Most people run these fans at the lower speeds to reduce odors in other parts of the house. In my experience a remote fan is common in a commercial kitchen but very rare in a residential kitchen. If you are going to use a fan larger than 400 CFM, you may have to provide an automatic make-up air system. that would only be worth it if you have a very large, high capacity, semi-pro gas range or the room is unusually large. I would not terminate an exhaust at a roof if I could possibly do it at an exterior wall. It's not a matter of efficiency but avoiding roof leaks and snow & ice in northern climates. I try hard to avoid all unnecessary penetrations in a roof because wall penetrations are easier to waterproof. I would do option C because it puts the termination away from windows and on a less important facade. Also, the ceilings/soffits can be easily built at 8 ft. from the floor and there would only be one 90 degree bend, and it might simplify the cabinet design. Be sure to get rid of the attic access hatch in the ceiling of the closet. You wouldn't be able to use it anyway and it is contrary to building code requirements.
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So, I finally have the venting done. The guys sure know how to drag ass. But, we finally came up with a plan and worked it out. Actually part of the delay was waiting for the cabinets to arrive. We decided to go through the wall and run ducting through cabinetry in the laundry room. We ordered really basic stock in white shaker style from Home Depot. I wanted to convert one tall cab into a broom closet, and only one collection had something that would work. The “stock” cabinets are not “in-stock” we had to special order, then we had to re-order one of the tall units FOUR times before we got an undamaged one! Ugh! Next our carpenter had some challenges installing them. We put a small upper in between two tall units (it’s a long story, but the configuration has a specific purpose for us.) they were almost finished when they realized the doors did not have enough room to operate, so the upper and left unit needed to be re-installed with filler. They also needed to order a special hole saw to fit the duct through the cabinets and exterior wall. Anyway, it was tedious, but finally done. I’ll tidy up the room and get new pics, but these show the point where they stopped the night they realized they had to add the filler. And a photo of the finished opposite side just waiting for the toe kick trim. We also got all the baseboard and other miscellaneous trim done too. I still need to fill nail holes and patch & paint, but I can finally call this main floor reno complete after 1.5 years! So relieved.
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steph1602
15 years ago
Same problem here, too. I did some research online and think that I might need a damper. I'm going to call my GC about it tomorrow.
marthavila
15 years ago
Yes, a backdraft damper may be exactly what's needed. I just had my hood installed last week. Afterwards, my GC said he needed to also install a springloaded backdraft damper. Not certain if such an item will be helpful to you or not but the main purpose of a backdraft damper is to keep out keeps cold air from coming into the house through the hood's ductwork when the hood is not in operation.

HTH
smilingjudy
15 years ago
Yes, you need a damper, sorta like this.

In my pre-reno kitchen, I put a couple of layers of foil just above the fan grids to try keeping the cold out. (The fan didn't work anyway.) I would constantly hear the foil crinkling and blowing in the breeze. (shudder)

New kitchen has the exact damper above...provided by my HVAC guys who custom fabricated my duct. No cold air. Works great!
brunosonio
15 years ago
You need a damper. Your HVAC or roofing guys can get you the right one, or it may come with the hood.

We vented our 900 cfm hood straight up to the roof and out, no bends. They installed a cap on the top that also had a damper in it. It keeps the rainwater and critters out.

I've not had any cold air coming down into the hood. I did have some water leakage, due to an improperly sealed seal around the hood pipe, which extends about 3 feet up past the roof. In wet Seattle here, that is more of what we have to worry about than cold air, LOL.
clax66
15 years ago
Oh, we had the same problem when we installed our 1200 cfm Viking Hood! Not surprising, as a huge hole had to be knocked out of our exterior wall.

As Marthavila wrote, you need to get a backdraft damper!

This was not easy: my BF had to special order a couple of times before we got one that correctly fit. Good luck!
brunosonio
15 years ago
We have the Wolf hood, and I think the damper/flue mechanism and piping came with the hood, or was ordered as part of the whole package.

I had my carpenter do the installation (I GC'd the whole renovation myself), and then had the roofing company check the work when they were out to fix some other stuff up there.
Raquel
5 years ago
I have the same problem and worried about oil and grease accumulating on these backdraft dampers. It doesn't seem like they are placed in places where it's easy to clean them and I worry about a fire hazard and the fact that when dirty they will not close properly. Thanks

cold draft coming in through Hood Vent... any ideas why???

davidro1

Comments (10)

Jean Farrell

redroze

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marthavila

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