Weil-McLain CGa-6
The CGa-6 continues the large CGa Series 4 sizes of the cast iron line discontinued in Canada in 2023: 166 MBH CSA input, 141 MBH DOE heating capacity and a 122 MBH net AHRI rating at 84% AFUE.
Key figures
- Max input
- 166 MBH
- Max CSA output
- 141 MBH
- AFUE
- 84 %
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Weil-McLain CGa-6 in practice
The CGa-6 fires at 166 MBH CSA input for 141 MBH of DOE heating capacity and a 122 MBH net AHRI rating at 84% AFUE, keeping the 6" vent size of the CGa-5. It belongs to the US-current Series 4 generation of Weil-McLain's cast iron natural-draft boiler, with stainless steel burners, a built-in low water cut-off and the vertical-flueway, top-cleaning design the US page promotes for servicing.
Canada's CGa history is tied to the June 30, 2023 production cut-off announced in Weil-McLain Canada's April 27, 2023 news release: contractors could keep buying and installing the Series-3-era Canadian units (52-245 MBH inputs) while inventory lasted, and parts are promised for at least 20+ years. This Series 4 model set is the successor generation sold in the US, so Boilers.ca records it under the discontinued CGa series with the generation clearly separated from the Canadian data.
Best suited to
- Homes and light-commercial loads near 140-166 MBH that vent through a chimney
- Contractors documenting the post-2023 US CGa Series 4 generation
- Cast iron boiler comparison work across the Canadian/US generation split
Applicability and support
- Model number
- CGa-6
- Canadian availability
- historical
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Not verified
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 | ||
| Input, maximum | 166 MBH | CSA input per the US Series 4 product page. |
| Output | ||
| DOE heating capacity | 141 MBH | DOE heating capacity per the US Series 4 product page. |
| Net AHRI water rating | 122 MBH | Net AHRI water rating per the US Series 4 product page. |
| Efficiency | ||
| Efficiency (AFUE) | 84 % | 84% AFUE per the US Series 4 page; the CA discontinued page lists up to 84% for the Series-3-era Canadian units. |
| Venting and air | ||
| Venting | Category I, B-vent — vertical chimney venting only, natural draft | Per the CA discontinued page (Cat. 1 venting, B-Vent; vertical vent only, 50 psi relief option); the US Series 4 page lists a 6" vent size for the CGa-6. |
| Operating limits and other | ||
| Fuel | Natural gas or propane | Propane requires a conversion kit per the CA product page. |
Manuals
- CGa Series 4 Boiler Manual, 550-100-223/0425550-100-223/0425 · 2025-04
Alerts documented for this model
- CONFIRM CONFIGURATION
- CONFIG MISMATCH
- AUTO LIMIT OPEN
- MANUAL LIMIT OPEN
- FALSE FLAME
- IGNITION FAULT
- FLAME LOST
- BOILER OUT OPEN
- BOILER OUT SHORT
- HARDWARE FAULT 1
- HARDWARE FAULT 2
- HARDWARE FAULT 3
- HARDWARE FAULT 4
- HARDWARE FAULT 5
- HARDWARE FAULT 6
- HARDWARE FAULT 7
- HARDWARE FAULT 8
- CH VOLTAGE HIGH
- DHW VOLTAGE HIGH
- SPILL SWITCH
Frequently asked questions
What are the CGa-6's ratings?
166 MBH CSA input, 141 MBH DOE heating capacity, a 122 MBH net AHRI rating and 84% AFUE, with a 6" vent size per the US Series 4 product page.
What generation of CGa was sold in Canada?
Weil-McLain Canada's discontinued page data covers the Series-3-era Canadian units at 52-245 MBH inputs, frozen at the June 30, 2023 cut-off; the Series 4 set is the US-current generation.
Is the CGa a condensing boiler?
No. The CGa is a cast iron, natural-draft boiler — the CA page lists it with Category I B-vent, vertical chimney venting only.
Questions about the Weil-McLain CGa-6?
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 Canada — CGa (discontinued) · accessed September 8, 2026
- Weil-McLain Canada — Residential boiler efficiency changes (Apr 27, 2023) · accessed September 8, 2026
- CGa Series 4 Boiler Manual 550-100-223/0425 · 550-100-223/0425 · accessed September 8, 2026
Facts checked September 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.