We had the Sears Specialist quote and size the Furnace & AC for our home. The furnace was sized as a 60,000 BTU and the AC was sized as a 2-ton. Since the installation of the unit we have had heating and cooling problems. I checked into the records of the previous owner and found the furnace was a 100,000 BTU and the AC was a 3-ton. Before this was revealed they insisted the ducts needed to be cleaned amd now they tell us it is a system problem. The other furnace operated for 18 years and the duct system has been in the home for 44 years! Sears created the system problems with the smaller units!! I'm trying to locate a load calculator for sizing of a furnace and AC since they say we only require 49,000 btu furnace. Any suggestions?