What's the best furnace for Calgary homes? It depends on your square footage, budget and how long you plan to stay. Homes under about 1,500 sq. ft. often do well with single-stage. Typical 1,500 to 2,500 sq. ft. family homes get the best value from two-stage, and larger homes with hot and cold rooms benefit most from modulating. Purcell Heating & Air's easy guide walks you through each option and explains why proper sizing matters as much as furnace type.