One contractor offered a 2 stage 80,000 gas furnace and when I asked him (the other quotations I have are for a 2 stage 60,000 gas furnace) why he said: "The furnace that we are going to install will run most of the time on low fire, which is around 50,000 BTU's. We recommend this furnace over a 60,000 BTU because the 60,000 will have to run a lot longer because it will be running on low fire which is around 35,000 BTU." I liked him a lot; he saw the chimney flue loose (and the house inspector had mentioned it in the report) and he fixed it right away (he just pushed it properly in place). I wonder whether the other contractors saw it. So I would have given him the contract even if a few hundred $ more expensive. But now, I do not know what to believe. Were all the other contractors wrong by offering a 60,000 furnace?