So i remodeled our bathroom a bit a couple of years ago. It originally had just a light fixture on the ceiling. I turned our bath tub into a shower/tub. And there used to be a window that i took out and made it glass block. So i needed to add an exhaust fan. I bought one with the light/fan combo. I installed it and just used the existing wire from light switch. Mind you i even went bigger than i needed for the size of our small bathroom as far as cfm's go. It directly vents up out of the roof of the house with no obstruction in vent piping. Ever since it was new it does not suck (or pull) air out of bathroom. Even with the light fixture decorative glass removed i can put a piece of tissue up and it immediately falls. So could it be possible to not have enough power from the original wired light to run the fan/light??? Its an older house with the 2 wire(neautral/hot) and uses conduit as ground...i believe. Is there a way for me to check it with my multi meter? Thanks in advance!

  • Do you have specs or a model number for the fan you installed? How long and big is the exhaust duct, and is it rigid or flex, for that matter? Sep 14, 2018 at 23:25
  • Its only 2-3 ft long rigid. Ill get specs and model number tomorrow.
    – T. Olson
    Sep 15, 2018 at 2:43
  • If you can get the shape and diameter of the exhaust duct while you're at it, that'd be wonderful as well! Sep 15, 2018 at 2:50
  • Also, I take it the fan/light is controlled by an ordinary wall switch, not a dimmer or any other sort of fancy thing? Sep 15, 2018 at 2:51
  • Nope just a regular light switch.
    – T. Olson
    Sep 15, 2018 at 10:36

1 Answer 1


There is a flapper (back draft damper) in the outlet of the exhaust fan. Make sure that it opens when the fan runs and is not stuck closed by anything including a mounting screw or discharge pipe item. Make sure that all the packing material has been removed from the fan housing. You can remove the fan and motor so you can inspect the vent damper. On the roof, make sure that the discharge damper assembly will open with any air movement. Hope this helps.

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