In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
I am working on a M# 199, 2004 vintage boiler. It is a modular system with 2 matched boilers. The customer complains that it backfires every couple of days. 2 months ago we had replaced the burner, gasket, door, insulation, electrode and flame rod. Yesterday, when I took the cover off, it seemed damp. On the top edge of the base there was moisture from the gas pipe to the control board. I couldn't find the leak, all the sensors, pipe and manifold connections and insulation were dry. I finally found it moist air coming from from the air venturi opening. There is no sign of a leak inside and there is no condensate (I have checked the trap and it is clean) during the off cycle.
Has anyone run across this before?
I am thinking i must have a small leak that evaporates all the evidence due to the hot heat exchanger.