XB80 backdraft damper won't open.
Just installed the fan and it vibrates badly. If run out of the housing it is whisper quiet. If I block the exhaust duct with a piece of cardboard it does the vibration thing. So we have a damper problem. I am venting with 4" up to a Y, then to a roof damper. I have no choice in the ducting. The damper swings freely. The fan I removed had no damper. So I am going to remove the damper, and wait for your answer. Oh, and this is in a second story bathroom, and I am not concerned about any upward heat loss, in fact I would welcome it! Dale.
PS: Is the plastic waffle grid necessary between the fan and the damper? Its presence made no difference.
6 months ago