We have had a water spot appear and not go away in our master bath. After looking around I found out that the flue pipe, B-Vent, is dripping with condensation when the furnace is running.
I have changed the heat cycle on the thermostat to a slow cycle so it stays on and off longer to hopefully allow the flue to heat enough to get the gas out.
I also took a look at the rain cap to see if it looked good. It did but I also noticed it seemed to be bottlenecking the gas badly. When I lifted it up, a lot more steam pushed out.
So my question is, could a too restrictive rain cap cause condensation on furnace flue pipes? Should I replace it with a more open one?
UPDATE: Changing the thermostat to slow cycle helped dramatically but there is still a small wet spot. Going to try a new rain cap.