I just received two estimates for a new 90% AFUE gas furnace for my 2300 sq. ft. house. We have a chimney that is steel on the inside. One guy (A), who actually estimated for a 93% AFUE, says we still should get a chimney liner; the other (B) says we don't need one (because of the steel). Both are from reputable companies, though 'A' is from a company that specializes in HVAC (and seems to be well thought of in that regard), while 'B' is from a large all purpose company that hasn't been reviewed here with regard to furnaces. 'B' estimate also came in significantly lower, even when you account for the liner. So, (1) any thoughts on the liner issue, and (2) is it the 93% for 'A' versus '90%' for 'B', or am I missing something, in that, factoring out the liner for 'A' for the moment, 'A' is around $2,100 and 'B' is around $1,400? Very large difference that has me uneasy.
Many thanks for your help.