Original Coleman furnace fading fast, now 35 years old. Have had back draft down chimney of CO. In Chinook country with lots of temp. swings. and even put one of those fancy caps on chimney with some help
House originally 1000 ft sq 4 level split with all 4 levels developed as dug down on 4th level when built. Over years added extensions on main floor (kitchen level) only with no full basements below (crawl area) and added duct work so now total 1350 ft sq. Do not need air conditioning.
Would appreciate suggestions on type and size. If need to do calculation where do i find calculator?