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Bought a house and now replacing the old range hood. The horizontal exhaust goes back then up but I noticed that not only is the initial part of the exhaust pipe not galvanized metal, it is wood and it is not completely connected to the metal piping that leads to the outside. I am not sure how the wood box is connected so not sure if it is easily removable but it does jiggle yet is remarkably clean for how long it must have been used (I am guessing 40+ years). How serious is this problem and are there simple solutions? Full view of range exhaust Here is a picture of the metal and wood not connected. Inside Exhaust looking up

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  • Why do you think there is a "problem". Typical rangehood would have a 3x10 stubout that gets inserted into that hole. There may or may not be access to apply duct tape over gaps. The exact location would be model-specific, so if you are not just reinstalling the unit in it's original location, you are looking at opening walls and creating new ductwork runs.
    – kreemoweet
    Commented Jan 11 at 1:05
  • @kreemoweet the problem is that while the hood would have a stubout, it would be very short, and may not seal up perfectly to the hole in the wall. Additionally, it appears that the hole in the wall is simply a wood manifold, and the joint at the (metal) duct which goes up is not sealed well. So some greasy air is probably bypassing the duct.
    – Huesmann
    Commented Jan 11 at 13:15

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I don't know your DIY skill level, but what I'd do personally is:

  1. Remove the cabinet. It should be screwed to the wall through the back, and possibly also to adjacent cabinets at the sides (possibly through the carcass, or through face frames). Note, what you discover when you remove the cabinet may alter the plan of attack.

  2. Measure the location of the wood box, then remove it. It'll be easier without the cabinet there.

  3. Get some metal duct to replace the box. If a 90º elbow will fit, use one. Otherwise you may end up having to cut some sheet metal. You effectively want a hole that can be mated up to the hood stubout. The hole should be slightly oversized to minimize fiddling to get the stubout into it. You can bend the sheet metal slightly if necessary. Tape any metal-to-metal joints with aluminum faced HVAC tape.

  4. Replace the cabinet.

  5. Get some foam rubber weatherstripping tape and box out around the hole. There isn't going to be a way to seal the hood-to-wall joint with tape due to lack of access, so the idea is when you press the hood back against the wall, the weatherstripping tape will provide the seal.

  6. Install the hood.

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  • Get some metal duct to replace the box is where it gets easier said than done real quick. - Putting an end cap on some rectangle is easy enough, or attaching an elbow, but if you have to cut your own hole and have left one inch to bend up for the Z strips, and one inch half bent over itself for the C strips... that's going to take you a few tries. Need shears, hand seamer, hand break, rubber mallet, and to mess with the old stuff you'll probably want a duct squisher. - Remove cab, +1. Possibly remove the section of duct that's mangled by taking the cleats off.
    – Mazura
    Commented Jan 11 at 14:58
  • The hole should be exactly the right size to cheat using just Z strips that you slip it into, all four at the same time w/o being able to see what you're doing.
    – Mazura
    Commented Jan 11 at 15:05
  • @Mazura that's why I say the plan may change depending what you find when the cabinet comes down. At that point it may be easier to simply R&R some drywall to replace a larger section of duct. I would certainly consider that.
    – Huesmann
    Commented Jan 12 at 14:05

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