I have condensation in/on the B'vent flue pipe from my heater in the attic andit is dripping. The original B-vent flue pipe was corroded on the interior so we had the flue pipe replaced from the heater to the roof ( with a high- wind cap as well). The heater is in the attic, and now when it runs we have condensation. The heater is 6 years old and has been checked out, they say it is fine. Installer of the pipe checked B'Vent and flue, cap etc. and said everything is done correctly. If it isn't the heater (could an adjustmetn be needed?) and the pipe they claim is correct (it has to travel a long way up to the room, maybe 24 feet from heater to roof) what can be done?? Water is dripping from about 3/4 of the pipe, down the pipe and into a bucket (fortunately) with white deposits left on the pipe and it is getting to the heater. The attic is a large, cold space in the winter, against a hot pipe. These people can't figure it out or don't want to?? Please any suggestions I would appreciate. Thank you.


You could add a fiberglass pipe insulation to the flue pipe to keep the flue gasses hot enough to prevent them from condensing. I had the same problem with the vent from my water heater so I covered the "B" vent with 1-1/2" thick fiberglass pipe insulation. The flue gasses no longer condense and the flue works great.

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  • Thank you so much! I will pass this along to the company dealing with this issue.
    – Marilyn
    Mar 23 '21 at 14:32

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