I live in a condo where a dryer and bathroom exhaust both connect into a Y connector that flows into the same pipe and into the building air shaft.

I understand that these two appliances on the same connection is not proper, and I was not aware it had been done that way when I moved in.

Usually the dryer functions fine, but twice in the past year I have had backdraft of hot moist air into the bath, covering the walls and ceiling with moisture and ruining some paint.

Since these both have to connect to the airshaft pipe at this point, though, the only solution I have come up with is a backdraft preventer installed on the connection to the bathroom exhaust.

Alternatively, where the pipe connects to the building airshaft I can have a fan installed to guarantee constant negative pressure. I am thinking the inconsistency of the backdraft issue may be because the air flow from the building air shaft varied for some reason? This is a higher cost job I cannot do myself.

I appreciate any advice within the constraints prevented. Also the dryer is electric so I am not concerned about safety beyond lint buildup.


  • Almost identical question: diy.stackexchange.com/questions/6166/…
    – Tim B
    Jan 10 '16 at 23:43
  • Just to be clear, you have a fan downstream from the dryer? That can be a bad idea unless it's a fan designed specifically for dryer vent lines.
    – DA01
    Jan 11 '16 at 3:48

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