Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Weil-McLain SF1000 and Weil-McLain SF1500 are two condensing boilers from the Weil-McLain SlimFit (Commercial) line. The Weil-McLain SF1000 is documented at 167–1,000 MBH input, 958 MBH gross output and 96.1% combustion efficiency, while the Weil-McLain SF1500 is documented at 250–1,500 MBH input, 1,437 MBH gross output and 96.1% combustion efficiency. Weil-McLain SF1500 lists 500 MBH more input than Weil-McLain SF1000 (1,500 MBH against 1,000 MBH). Both list the same published combustion efficiency of 96.1%.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Weil-McLain SF1000 | Weil-McLain SF1500 |
|---|---|---|
| Minimum input | 167 MBH | 250 MBH |
| Maximum input | 1,000 MBH | 1,500 MBH |
| Gross output | 958 MBH | 1,437 MBH |
| Combustion efficiency | 96.1 % | 96.1 % |
| Turn-down ratio | 6:1 | 6:1 |
| Domestic hot water | Heating-only commercial boiler — domestic hot water comes from a separate indirect tank or water heater | Heating-only commercial boiler — domestic hot water comes from a separate indirect tank or water heater |
| Supply / return water connections | 3" ASME Class 150 | 3" ASME Class 150 |
| Gas connection and pressure | 2" NPT male; 3"–14" w.c. | 2" NPT male; 3"–14" w.c. |
| Fuel | Natural gas; optional LP on the smaller sizes per the page | Natural gas; optional LP on the smaller sizes per the page |
| Net AHRI rating | 1,833 MBH | 1,250 MBH |
| Vent/air diameter and length | 6" or 8"; 100 ft or 150 ft | 8"; 100 ft |
| Control | SlimFit control with 3.5" LCD screen; Modbus standard, BACnet optional | SlimFit control with 3.5" LCD screen; Modbus standard, BACnet optional |
| Heat exchanger | Sectional aluminum block with stainless steel burner (woven steel fiber mesh) | Sectional aluminum block with stainless steel burner (woven steel fiber mesh) |
Published ratings: the Weil-McLain SF1000 is rated 167–1,000 MBH input, 958 MBH gross output and 96.1% combustion efficiency; the Weil-McLain SF1500 is rated 250–1,500 MBH input, 1,437 MBH gross output and 96.1% combustion efficiency. Weil-McLain SF1500 lists 500 MBH more input than Weil-McLain SF1000 (1,500 MBH against 1,000 MBH). Both list the same published combustion efficiency of 96.1%.
The vent/air diameter and length differs: the Weil-McLain SF1000 lists 6" or 8"; 100 ft or 150 ft, while the Weil-McLain SF1500 lists 8"; 100 ft.
Both records print the same combustion efficiency (96.1%), turndown (6:1), domestic-hot-water arrangement (Heating-only commercial boiler — domestic hot water comes from a separate indirect tank or water heater) and water connections (3" ASME Class 150), per the cited sources.
Weil-McLain
The Weil-McLain SF1000 is a current commercial condensing gas boiler in the SlimFit line: 167–1000 MBH input, 958 MBH gross output and a 1833 MBH net printed page rating at up to 96.1% combustion efficiency, with 6" or 8" venting and a sectional aluminium block heat exchanger.
Weil-McLain
The Weil-McLain SF1500 is a current commercial condensing gas boiler in the SlimFit line: 250–1500 MBH input, 1437 MBH gross output and a 1250 MBH net printed page rating at up to 96.1% combustion efficiency, with 8" venting and a sectional aluminium block heat exchanger.
The Weil-McLain SF1500 lists 1,500 MBH, against 1,000 MBH on the Weil-McLain SF1000, per the cited documentation.
Both list the same combustion efficiency of 96.1%.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.