Modify existing duct in drywall


Old 03-20-15, 02:03 PM
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Modify existing duct in drywall


My existing duct used to extend to 6" above the floor and then had a 90 deg. joint and came straight out. It fit inside a custom bookcase.

I have removed the bookcase and I want to extend the duct to the floor, then add a 90 deg joint and have it come out of the toe kick of a kitchen cabinet.

I have tried to remove the 90 deg joint and I have even taken the tin snips to it.

Once I get it out, how do install the extension to bring it to the floor and the new 90 deg duct?

The duct fits almost perfectly between 2 studs. If I take out a vertical strip of drywall, will I be able to disconnect the duct higher up?

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Old 03-20-15, 02:32 PM
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Tough questions. It is possible the duct is one piece and goes all the way to the attic with no joints until it gets there. Or, it could have a joint just above the point where you stopped removing the drywall. If the latter it probably has what are called S-clips on the longer dimension and drive cleats on the shorter dimension and IF this is true then you would have to remove the drywall to above the drive cleats and then attempt to pull them off. This might be near to impossible if the installer bent over the tabs at the back end.

Can you take a (flash) picture up the duct so we can see if there is any joint near to the outlet?
Old 03-20-15, 04:12 PM
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Thanks for the response Furd.

I tried to take some pictures up the duct, but it's almost impossible to see anything.

I did have some success using a mirror and flashlight. It looks like it is one continuous piece - 7.5 to 8 ft long. At the top it transitions 90 deg to a circular duct. It looks like there are 2 screws in the front and 1 in the back that attach this 90 deg / circular transition piece.

I'm having quite a difficult time taking the drive cleats out of the back at the bottom. They have been bent over the back end.

I'm on vacation next week, so I have some time to think about what to do. I don't mind taking out the whole vertical section (approx 10" wide by 8 ft tall), but that's a lot of work if it won't get me any closer to a solution.
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Old 03-20-15, 05:07 PM
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If the drives are just a single layer of sheet metal, you can usually grap the exposed end with a pair of vice grips & pull. Usually this will straighten out the tab on the back. If the drive is double layer, all bets are off.
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