Weil-McLain · SlimFit (Commercial)
Weil-McLain SF750
The Weil-McLain SF750 is a current commercial condensing gas boiler in the SlimFit line: 150–750 MBH input, 702 MBH gross output and 610 MBH net AHRI at up to 94% combustion efficiency, with 6" or 8" venting and a sectional aluminium block heat exchanger.
Key figures
- Max input
- 750 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 150 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Weil-McLain SF750 in practice
The SF750 is one of the five current SlimFit commercial condensing gas sizes documented on Weil-McLain's official SlimFit page. Its Technical Specs row prints 150–750 MBH input, 702 MBH gross output and 1610 MBH in the net column (the official 550–750 submittal prints 610 — both sources are recorded as printed). Venting is 6" or 8" with 30 ft, 100 ft allowable length in PVC, CPVC, PP, ABS or AL29-4C, on 1-1/4" NPT male gas at 3.5"–14" w.c. and 2" ASME Class 150 supply/return connections.
The boiler uses a sectional aluminium block heat exchanger with a stainless steel woven-fiber burner, sealed combustion, direct spark ignition, a variable-speed blower and a negative-pressure regulated gas valve; the submittal prints 94% combustion efficiency and 93.6% thermal efficiency for this size. Control is the SlimFit platform with a 3.5 in. LCD screen, preset heating systems, 0-10 VDC output, Modbus standard and BACnet optional, cascading up to eight boilers with lead/lag rotation and up to 24 zone inputs/outputs.
Boilers.ca records the printed spec row for the SF750 for commercial service planning. No official Canadian-sales statement was found on the US product page reviewed, so canadianStatus stays 'unknown'; commercial gas, combustion and venting work belongs with a licensed contractor against the model's own SlimFit boiler manual.
Best suited to
- 150–750 MBH commercial condensing loads
- Plants wanting a sectional aluminium block boiler with cascade control
- Buildings planning 8-boiler lead/lag systems with up to 24 zones
Applicability and support
- Model number
- SF750
- Canadian availability
- unknown
- Production status
- current
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Series terms
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by Weil-McLain. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Maximum input | 750 MBH | Maximum input per the official SlimFit Technical Specs table. |
| Minimum input | 150 MBH | Minimum input per the official SlimFit Technical Specs table. |
| Output | ||
| Gross output | 702 MBH | Gross output per the official SlimFit Technical Specs table. |
| Net AHRI rating | 610 MBH | The official page's Technical Specs table prints 1610 MBH in its net column for this size while the official SlimFit submittal prints 610 MBH net AHRI; both are recorded as printed (the page value appears misprinted). |
| Efficiency | ||
| Combustion efficiency | 94 % | Combustion efficiency per the official SlimFit 550–750 submittal's AHRI ratings table. |
| Thermal efficiency | 93.6 % | Thermal efficiency per the official SlimFit 550–750 submittal's AHRI ratings table. |
| Domestic hot water | ||
| Domestic hot water | Heating-only commercial boiler — domestic hot water comes from a separate indirect tank or water heater | |
| Venting and air | ||
| Vent/air diameter and length | 6" or 8"; 30 ft, 100 ft | Vent material PVC, CPVC, PP, ABS or AL29-4C per the Technical Specs table; certified Category II/IV venting. |
| Physical and connections | ||
| Gas connection and pressure | 1-1/4" NPT male; 3.5"–14" w.c. | Gas connection size and min/max gas pressure per the Technical Specs table. |
| Supply / return water connections | 2" ASME Class 150 | Supply/return water connection per the Technical Specs table. |
| Operating limits and other | ||
| Turn-down ratio | 6:1 | The SlimFit 1000–2000 submittal prints a modulating burner with 6:1 turndown; the 550–750 submittal documents the same sectional aluminium block platform. |
| Control | SlimFit control with 3.5" LCD screen; Modbus standard, BACnet optional | Per the 550–750 submittal: preset typical heating systems, 0-10 VDC output, up to 8-boiler cascading with lead/lag rotation, up to 24 zones. |
| Heat exchanger | Sectional aluminum block with stainless steel burner (woven steel fiber mesh) | Per the SlimFit 1000–2000 submittal standard features; sealed combustion, direct spark ignition, variable-speed blower and negative-pressure regulated gas valve. |
| Fuel | Natural gas; optional LP on the smaller sizes per the page | The official page notes optional LP on the smaller sizes. |
Manuals
Alerts documented for this model
None documented yet.
Frequently asked questions
What are the SF750's ratings?
150–750 MBH input and 702 MBH gross output per the official Technical Specs table; the official submittal prints 610 MBH net AHRI where the page table prints 1610.
What venting does the SF750 use?
6" or 8" vent/air connections with 30 ft, 100 ft allowable length in PVC, CPVC, PP, ABS or AL29-4C; the line is certified for Category II and Category IV venting.
How many SlimFit boilers can cascade?
Up to eight boilers with lead/lag rotation per the submittal, with multiple system functionality, series/parallel or smart sequencing and up to 24 zone inputs/outputs.
Questions about the Weil-McLain SF750?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- Weil-McLain — SlimFit Commercial Condensing Gas Boiler (SF750) · accessed September 9, 2026
- SlimFit 550-750 Boiler Manual, 550100559_0725 (Jul 2025) · 550100559_0725 · accessed September 9, 2026
- SlimFit 550–750 Submittal · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.