Not sure why your calling me out here.You clearly have not done your homework.I was just stating that flue temps on high efficiency boilers in general are too cool to draft properly out a conventional chimney which was the purpose of my response.They would have to have a forced draft.Can they have flue temps higher than 140?Of course.Thats not what the point of my post were.Regular pvc softens at 140 so it would not be my choice but it has been used for years.Would I use it?No.But thats not the point,.I stand by my post.
Because of the special heat exchanger technology used by a condensing
furnace, heat is extracted from the fuel combustion process for a longer period of time, to the point where the combustion exhaust gasses have "cooled" and condensed. The exhaust gasses are depleted of heat until the water condensate drips out of the furnace's heat exchanger and the low-temperature flue gasses escape from special plastic pipe instead of a chimney.
Traditional gas-fired, forced-air furnaces used metal venting, usually routed into a chimney stack, then exhaust the combustion gasses. But in the modern high-efficiency condensing furnaces, special plastic pipe material (most often PVC, ABS or CPVC) is used for air intake.
Generally, for a new condensing water heater or boiler, the stack temperature will be about 20 degrees higher than the water temperature.
http://www.plumbingengineer.com/cont...ial-flue-gases
The point was that chimneys are not needed for these boilers and in fact need a forced draft.And yes it sure seems you are here to ague.I'm done.