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Discussion Starter · #1 ·
I live in sunny Winnipeg, Canada where the winter's get to -35 C (and F), keep than in mind as far as condensation goes when contemplating this question.

I am venting a range hood (island style, 6 inch duct). It will travel 6 feet through the ceiling joists between the first and second floor of my home (heated space), and then will go through the exterior wall into the attic space of an unheated/uninsulated sunroom. The duct will then go out the wall to the termination point on the exterior of the sunroom.

My hood instructions call for the installation of ONLY one damper in the system, and provides a damper than mounts directly on the top of the hood. It does state though that you can mount a damper anywhere in the run provided that you do not use the one on the hood itself.

Im trying to minimize risks of the condensation forming in my duct and leaking foremost in the heated space, but also in the unheated sunroom space.

With that in mind, where should I place the damper?

1) Use the provided damper that attaches directly to the range hood. This will leave the entire 6 foot run of heated plus 6 feet of unheated run after the duct.

2) Place a damper at the point where the heated space meets the unheated space.

3) Place the damper at the end of the run after both the heated space and unheated space.

I would say Im leaning works option #2, but Im open to suggestions.



· Registered
17,837 Posts
You have to insulate the part of the run in the unheated space.

Also run the fan for a few minutes after each use to clear out the moisture.

Do both and it won't matter where it's dampered. Exhaust fans for bathrooms have the damper in the fan itself and they work fine.

Keep service into consideration. If damper gets jammed, breaks etc and is not accessible, it will be hard to deal with.

Try to get a metal outlet if you can.There are some really cheap plastic ones last maybe 10 years; the UV sunlight destroys the plastic.

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