Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Weil-McLain CGi-3 and Weil-McLain CGi-4 are two non-condensing boilers from the Weil-McLain CGi (cast iron) line. The Weil-McLain CGi-3 is documented at 58 MBH input, 49 MBH output and 84% AFUE, while the Weil-McLain CGi-4 is documented at 90 MBH input, 77 MBH output and 84% AFUE. Weil-McLain CGi-4 lists 32 MBH more input than Weil-McLain CGi-3 (90 MBH against 58 MBH). Both list the same published AFUE of 84%.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Weil-McLain CGi-3 | Weil-McLain CGi-4 |
|---|---|---|
| Input, maximum | 58 MBH | 90 MBH |
| DOE heating capacity | 49 MBH | 77 MBH |
| Efficiency (AFUE) | 84 % | 84 % |
| Venting | Category I B-vent (chimney) or Category III AL29-4C stainless steel (sidewall) | Category I B-vent (chimney) or Category III AL29-4C stainless steel (sidewall) |
| Fuel | Natural gas or propane | Natural gas or propane |
| Net AHRI water rating | 43 MBH | 67 MBH |
Published ratings: the Weil-McLain CGi-3 is rated 58 MBH input, 49 MBH output and 84% AFUE; the Weil-McLain CGi-4 is rated 90 MBH input, 77 MBH output and 84% AFUE. Weil-McLain CGi-4 lists 32 MBH more input than Weil-McLain CGi-3 (90 MBH against 58 MBH). Both list the same published AFUE of 84%.
Both records print the same AFUE (84%), venting (Category I B-vent (chimney) or Category III AL29-4C stainless steel (sidewall)) and fuel (Natural gas or propane), per the cited sources.
Weil-McLain
The CGi-3 is the second-smallest CGi Series 5 size of the cast iron line Canada discontinued in 2023: 58 MBH CSA input, 49 MBH DOE heating capacity and a 43 MBH net AHRI rating at 84% AFUE.
Weil-McLain
The CGi-4 is the mid-size CGi Series 5 model of the cast iron line discontinued in Canada in 2023: 90 MBH CSA input, 77 MBH DOE heating capacity and a 67 MBH net AHRI rating at 84% AFUE.
The Weil-McLain CGi-4 lists 90 MBH, against 58 MBH on the Weil-McLain CGi-3, per the cited documentation.
Both list the same AFUE of 84%.
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.