I have to run a length of about 3 meters of duct (from the fan to the outside), where there will be 2 90° bends. I was going to use plastic flexduct, but I can make the bends bends and some of length using 100mm PVC.

Is it worth the hassle of doing pipe work instead of just running flex duct? I live in Brazil, and I don't see much condensation getting trapped for long with our temperatures.

  • 1
    I think PVC pipe would be better than flex it is smooth and will not leak after years of service like flex can.
    – Ed Beal
    Aug 12, 2016 at 0:47
  • ...and smooth translates to more airflow from the same fan due to less duct resistance. Remember to slope the majority of the pipe downward to the exit for condensation (there will certainly be some in a bathroom duct.)
    – Ecnerwal
    Aug 12, 2016 at 2:11
  • If you live in a colder climate, do not slope the pipe towards the outside. If you live in the US (which obviously the OP does not) check local codes, as most (I believe) require the duct to slope towards the interior not exterior.
    – Tester101
    Aug 12, 2016 at 11:17
  • @Tester101, do you know why is that? Aug 12, 2016 at 11:31
  • 1
    @LuizBorges In colder climates, it's so you don't block the pipe up with ice. Code wise, it's probably easier to have it always slop in, rather than base the slope direction on location. US codes cover a wide range of climates.
    – Tester101
    Aug 12, 2016 at 11:46


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