Bathroom Fan Vent...Cold Climate

As always, I appreciate your responses.

Glenn F.

Vents by code are required to be rigid duct.

This is too keep exhaust gas form collecting in a low section of the vent duct that would happen if using flexable duct.

By using rigid pipe you are creating a natural exhaust flow weather the fan is on or not. This can not happen if using flex duct.

12ft is a very long run for a bathroom vent and will exceed the static pressure (resistance to air flow) of the fan rating. Be sure this is with-in the mfg spec rating for your vent.

90� EL's are not allowed on vents and 45� EL's or less work the best. You can use the 90�"L" to make a 45� by adjusting each of the gores(segments).

Bathrooms are required to be a negitive pressure design to keep unwanted gases contained only to that room.

T_Bone

If you go through the wall you can use PVC to keep the inner wall smooth and stop condensate build up. I would pitch it toward the outlet a bit and insulate the pipe along it's length.

I put my fans on timers and always run them for about 10 minutes after I step out of the shower. This allows them to pull more moisture out and it keeps the condensate moving out the vents.

Timers are also handy if you find foul odors in the bathroom. Crank it to 5~10 minutes and walk away. All will be well and you don't have to go back and turn it off manually.