I have a vent for the microwave-range that goes from an interior kitchen wall to the outside of the house. I need to re-locate this, but I can't move the exterior vent fixture. It currently comes in the house with a 6" galvanized ducting pipe about 18" long before it transitions to flex duct.

Is there an immediate 90 degree elbow that I can put directly on the outside vent so that as soon as it comes in the wall, it goes vertical within the studs, instead of jutting into the house so far? I would like to essentially go up with it about 8 inches and then transition it back to the flex pipe.

  • Someone good with sheet metal could make a custom piece that's a 90 degree bend with a round opening at one side and a rectangular one at the other.
    – fixer1234
    Aug 5, 2018 at 3:02

2 Answers 2


I'd just get a length of rectangular 3-1/4 x 10 duct, capped on both ends, and connect to it low and high with starting collars. Seal things up nicely with silicone caulk or foil tape.

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                         ||     || <-- end cap
                        __|     |
                          .     |
starting collar in -->    .     | <-- box duct
                        __.     |
                          |     |
                          |     |
                          |     |
                          |     |__
                          |     .
                          |     .   <-- starting collar out
                          |     .__
                          |     |
  • Well, its far too late for me, but I think that's a great answer
    – Derek
    Jan 17, 2020 at 4:03
  • Thanks. Yeah, maybe next time respond to the more timely questions to keep interest up. d.george asked you for clarification and got no feedback.
    – isherwood
    Jan 17, 2020 at 14:00

Do you want the pipe to stay round or can it be changed to a rectangle? If it is to stay round, just install an adjustable elbow and if it is a round to rectangle that you want a 10" X 3-1/4" to 6" round 90 degree stack boot.

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