Measurement Guide

Use the map above to determine your region and compare to the chart below to find your application size.
80% AFUE Gas Furnace (Multi-Positional) Selection
Region 1 Region 2 Region 3 Region 4 Region 5 Furnace Size
624-780 675-840 750-940 915-1140 1025-1280 40,000 BTU
780-1170 840-1260 940-1410 1140-1710 1280-1925 60,000 BTU
1170-1560 1260-1680 1410-1880 1710-2280 1925-2550 80,000 BTU
1560-1950 1680-2100 1880-2350 2280-2850 2550-3200 100,000 BTU
1950-2340 2100-2525 2350-2825 2850-3425 3200-3850 120,000 BTU
Residential Sizing: The table and charts are intended to be used as a guideline for Residential applications only.
The information is based on conventional window space (<15%), insulation and building construction (8 ft.
ceiling height). When including a finished basement, use 1/2 of the finished basement square footage with
the rest of the area being calculated.
Mobile/Manufactured Home Sizing: Refer to the Date Plate located in the electrical box or kitchen cabinets. For
further assistance, call Hamilton's customer service department [phone].
Square Footage
Equipment Sizing Guide