I have 10 yrs old, Amana 80% efficiency gas furnace and it vents out through b-vent flue pipe. The b-vent pipe leaks in attic and basement due to condensation.
I hired a HVAC pro to diagnose the problems. He used an analyser and found that the flue gas temperature is only around 225F and this low temperature results in condensation in the b-vent pipe. He mentioned that it should be around 300F for the proper venting of flue gases without condensation.
He found that the furnace is also short cycling. He adjusted the gas supply which helped to minimize the short cycling to some extent. But, it didn't increase the flue gas termperature.
He spent more time trying to get the flue temperature high. But, he was not successful.
He finally recommended changing the furnace unit which I don't like to do.
Please, help me with my situation now. Did he miss something in his diagnosis? How to increse the flue gas temperature? Any help is appreciated. Thanks a lot.
[Edited by sanrishi on 02-15-2005 at 02:28 PM]