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There are many questions on here about installing duct work for bathroom fans, but I have a more specific question. I am planning to use rigid duct for a new bathroom fan where there was none previously. The fan is installed under the attic floor, which is currently removed for other work. After the floor is re-installed and the attic room re-finished, I would like to be able to replace the bathroom fan (as I will probably have to some day) without having to cut additional holes in the bathroom ceiling (lathe and plaster) or attic floor.

How do I remove the bathroom fan from the ceiling if it is rigidly connected to the rigid duct? Most online videos show flex duct, and you can simply pull the sidewall part of the fan assembly down from the ceiling enough to disconnect the clamp. With rigid duct, this is obviously not possible.

My original plan was to connect the rigid duct to the fan with screws and mastic. Could there be some other method, like a clamp with rubber insert on the ID to hold a strong connection and provide an air seal, that could potentially be removable? I could imaging either wiggling the sidewall back and forth to pull it loose from such a clamp, or maybe reaching over the fan sidewall to loosen a securing nut (joist bays are only 2x6). Any suggestions are appreciated.

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I'd think about stopping the rigid duct about two feet from the fan and connecting a piece of aluminum flex duct to the end of the rigid and on to the fan. You'd have some flexibility in removing the fan in the future. If you're hell bent on rigid all the way, replace the old fan now with a new one, vent it up solid with your rigid and buy an exact additional fan for the future replacement of parts without having to replace the housing and messing with the rigid connection..

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  • I ended up going with your first suggestion. I got the "semi-rigid" aluminum flex duct, not the classic flexible dryer vent type line. I kept it mostly in its original compressed length, and connected one end to the fan exhaust port and the other to 4" rigid using band clamps. I also sealed both sides with a liberal amount of mastic. – blarg Jun 2 at 0:58

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