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Range hood vent through roof or gable end?

pbyar | Posted in Energy Efficiency and Durability on

Claimed 760 max cfm range hood. I suspect 300 cfm actual will be closer to the truth. Make-up air issues aside, 6″ round, mastic sealed metal duct can go:
-up 7 feet (5 feet from ventilated attic floor) and out through 4:12 roof facing prevailing winds or
-up 2 feet, 90 degree elbow and 15 feet out gable end which is parallel to prevailing winds.
My inclination is to leave the roof undisturbed and perhaps avoid force-fed cold air leaking past the damper. Good plan or not?
Climate zone 4a, NJ

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Replies

  1. Chaubenee | | #1

    Without knowing more, I tend to want to see such penetrations made through walls rather than roofs. The less holes in a roof the better, in my humble opinion, especially a low pitched roof. Perhaps I am daft but usually kitchens have a window which usually means they are often bounded by at least one outside wall. Is the range/cooktop on some island far from the outer wall? However I think it isn't uncommon for those ducts to travel that distance.

  2. GBA Editor
    Martin Holladay | | #2

    Peter,
    Through the wall is better. If the horizontal duct has to travel through a vented unconditioned attic, make sure that the duct is very well insulated.

  3. pbyar | | #3

    Thanks very much for the guidance, guys. Joe, yes, it is an island hood. Martin, I'll pile on the insulation; thanks for mentioning it.

  4. davidmeiland | | #4

    Go out through the wall. You can get much better backdraft dampers for wall applications.

  5. pbyar | | #5

    Thanks, David. Any recommendations? I just ordered a Broan damped wall vent cap, but it's not too late to zig.

  6. davidmeiland | | #6

    Seiho makes the best I have found.

  7. pbyar | | #7

    Thanks for the tip, David.

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