Weil-McLain SF750 vs SF1000

Published ratings: the Weil-McLain SF750 is rated 150–750 MBH input, 702 MBH gross output and 94% combustion efficiency; the Weil-McLain SF1000 is rated 167–1,000 MBH input, 958 MBH gross output and 96.1% combustion efficiency. Weil-McLain SF1000 lists 250 MBH more input than Weil-McLain SF750 (1,000 MBH against 750 MBH). Weil-McLain SF1000 lists 2.1 percentage points more combustion efficiency than Weil-McLain SF750 (96.1% against 94%).

The water connections differs: the Weil-McLain SF750 lists 2" ASME Class 150, while the Weil-McLain SF1000 lists 3" ASME Class 150. The gas connection differs: the Weil-McLain SF750 lists 1-1/4" NPT male; 3.5"–14" w.c., while the Weil-McLain SF1000 lists 2" NPT male; 3"–14" w.c. The vent/air diameter and length differs: the Weil-McLain SF750 lists 6" or 8"; 30 ft, 100 ft, while the Weil-McLain SF1000 lists 6" or 8"; 100 ft or 150 ft.

Both records print the same turndown (6:1), domestic-hot-water arrangement (Heating-only commercial boiler — domestic hot water comes from a separate indirect tank or water heater), fuel (Natural gas; optional LP on the smaller sizes per the page) and control (SlimFit control with 3.5" LCD screen; Modbus standard, BACnet optional), per the cited sources.