We have a 2-zone heating and A/C system. We are replacing the gas water heater and 1 of the 2 gas furnaces.
The water heater will be replaced with a same capacity unit. It will not be a high efficiency unit.
The existing 110,000BTU Lennox furnace (circa 1968) will be replaced with an 80,000 BTU 2spd. Trane 80% efficiency unit. We were told by 1 of the companies that we met with that he is 95% sure that we'll need to get a new, smaller liner for our chimney flue. He said that the exhaust from the newer, more efficient water heater and furnace could cause condensation problems and potentially damage the heat exchanger. He further said that Trane would not honor the warranty if the exchanger damage was caused by this situation.
It makes sense, yet we're concerned that he is the ONLY person who mentioned it out of 3 Trane dealers + 1 American Standard dealer.
Any comments are appreciated