Matching the CFM capacity of the ducts to the new furnace is more important
than a heat loss calculation. In some cases, drawing combustion air from
inside is preferable. Large amounts of some chemicals can ruin a heat
exchanger, but most people don't have that situation.

wrote in message
oups.com...
I would get at least 3 and preferably 5 estimates and quotes, then
compare.

did he measure you entire home and do a heat loss calculation??

since he advocated downsizing the hot water tank I would question his
other recomendations

you better off using outside air for combustion, old houses already
exchange air enough and besides certain home chemicals have caused
furnace heat exchanger failures in the past. everything I have seen
says outside cold air, is more dense and better.

how long has he been in business? buy a furnace ONLY with a lifetime
heat exchanger warranty and at least 10 year parts and labor for
everything else.

are you buying a 2 speed furnace? they run on low speed in moderate
temps, then step up for more demanding situations like zero days.
slightly more expensive, but selling point if your moving