Hey everyone, Im a hvac/r tec and i have a bit of a head scratcher. Im working on a mid efficiency keeprite. The pressure switch hose is filling up with water every few days. I think the issue is in the venting. The furnace is 100k btu and the total lateral length of the vent is 15ft with 18" rise. However the venting is C vent not B vent (first issue). This furnace is 11 years old and this is the first time this has happened. I have noticed some water marks coming from the clay tile chimney that has a 4" liner in it. I think the liner is deteoriating but I cant tell without removing it. The reason I think the liner is deteoriating is because there is C vent where B vent should be present and I think there is excess condensation in the chimney liner. Has anyone ever had this problem before? What do you think the causes of the water in the pressure switch tube could be?