Weil-McLain CGa-4
The CGa-4 is the mid-size CGa Series 4 model of the cast iron line discontinued in Canada in 2023: 100 MBH CSA input, 85 MBH DOE heating capacity and a 73 MBH net AHRI rating at 84% AFUE.
Key figures
- Max input
- 100 MBH
- Max CSA output
- 85 MBH
- AFUE
- 84 %
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Weil-McLain CGa-4 in practice
The CGa-4 fires at 100 MBH CSA input for 85 MBH of DOE heating capacity and a 73 MBH net AHRI rating at 84% AFUE, with a 5" vent size per the US Series 4 page. It is a cast iron, natural-draft gas-fired water boiler in the current US Series 4 generation, featuring stainless steel burners, a built-in low water cut-off, compact construction and easy top-access cleaning of vertical flueways.
Weil-McLain Canada discontinued the CGa in 2023: its news release of April 27, 2023 announced a production cut-off of June 30, 2023 for non-condensing residential boilers under 300,000 BTUH, with boilers available only while inventory lasted and parts promised for at least 20+ years. weil-mclain.ca's discontinued page data corresponds to the Series-3-era Canadian generation (inputs 52-245 MBH, vertical B-vent only), so this Series 4 CGa-4 documents the US-current successor rather than the Canadian-era units themselves.
Best suited to
- Chimney-vented homes with heat-loss loads in the 85-100 MBH band
- Contractors documenting the US CGa Series 4 that Canada never sold new after 2023
- Replacement research on cast iron natural-draft boilers for B-vent installations
Applicability and support
- Model number
- CGa-4
- 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 | 100 MBH | CSA input per the US Series 4 product page. |
| Output | ||
| DOE heating capacity | 85 MBH | DOE heating capacity per the US Series 4 product page. |
| Net AHRI water rating | 73 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 5" vent size for the CGa-4. |
| 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
Is the CGa-4 available in Canada?
No. The CGa was discontinued in Canada with a June 30, 2023 production cut-off per Weil-McLain Canada's April 27, 2023 news release; Series 4 units like the CGa-4 continue only in the US market.
What venting does the CGa-4 need?
It is a natural-draft boiler for Category I B-vent vertical chimney venting; the US Series 4 page lists a 5" vent size for the CGa-4.
What are the CGa-4's ratings?
100 MBH CSA input, 85 MBH DOE heating capacity, a 73 MBH net AHRI rating and 84% AFUE per the US Series 4 product page.
Questions about the Weil-McLain CGa-4?
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.