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I'm replacing a bathroom ceiling fan, and need to add a short extension (approximately 18") to the length of the existing vent hose. The existing hose is 4" aluminum flex.

I have a couple questions. First, would it be acceptable to use the softer foil flex for the extension? The added flexibility would be nice during installation, and since it is a fan vent and not a dryer vent I assume the fire risk isn't an issue.

Secondly, what's the best way to attach and seal the connection? Screws, tape, hose clamp, etc? Ideally it would be something that I could install in tight quarters to avoid having to open another section of drywall--although I'd definetely prefer a good connection over the installation convenience.

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up vote 2 down vote accepted

You would use a coupling tape and hose clamps. You use thin flex aluminum duct like shown in picture but I like to stick with the semi rigid flex duct. Zip ties can be used on thin stuff but not semi rigid.

enter image description here

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Cool, I haven't seen those before – STW Mar 10 '14 at 14:46

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