Replacing ducting


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Old 02-02-19, 04:22 PM
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Replacing ducting

Up in the attic, I noticed a bath fan (4 in.) was connected to 3 in. ducting with just duct tape and no reducer. Furthermore, the ducting at the roof end looked quite mangled. My guess is it had been that way for at least 10 years, however with cold but not freezing temps, it doesn't seem to have caused other damage. [image]

With that said, I believe the proper thing to do is to replace the existing 3 in. with new 4 in. ducting. A couple questions come to mind:
  1. Besides the UL cert, is this regular duct worse in build quality than the "Heavy Duty" duct? The local Lowes has the same two types but doesn't claim one to be heavy duty.
  2. What type of connection at the roof will I likely be dealing with? Should I be prepared with some screws, foil tape, clamp, or other?
 
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Old 02-02-19, 10:36 PM
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Assume the duct is just a material thickness, either will work.

Connection depends on what you are connecting to, a vent of some sort?

Have seen some with hose clamp connections, other are attached with screws!
 
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Old 02-03-19, 12:13 PM
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My plan is to connect to the existing roof vent with a 4 to 3 in. galvanized steel reducer. It'll be interesting to see how the duct is holding on and whether there is actually anything securing it.
 
 

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