There is water dripping out of the seams of a vent pipe (single wall heater and hot water vent pipe in the attic going through the roof). It was really cold out side(12 degree). The pipe was hot to the touch and it hasn't rain it at less 5 days. I said it was condensation the heat & air guy is saying its a leak. I don't see how water can stay in a hot vertical pipe for more than 5 days or just one day. Does any have an ammunition or advice that would help with the decision.