Weil-McLain CGa Series 4
Model Number: CGa
CGa Series 4 hot-water boiler, 84.0% AFUE, 38,000-233,000 BTU/hr range
Technical Specifications
Source: manufacturer spec sheet · checked Sep 27, 2026
Prices depend on sizing, venting and piping in your home, so we quote every installation.
Sizing: the right size comes from a room-by-room heat-loss calculation, not the size of the old boiler or a rule of thumb. Oversized boilers short-cycle and waste fuel; steam systems are sized to the connected radiation instead. See how we approach boiler installation.
Home-Specific Operating Cost Review
No guaranteed annual savings or payback period
Historical Use
Fuel consumption and weather
Current Rates
Utility and delivered-fuel prices
System Design
Load, piping, controls, and temperatures
Full Specifications
- Model Number
- CGa
- Efficiency (AFUE)
- 84%
- Boiler Type
- Hot Water Boiler
- Fuel
- natural gas/propane
- Venting
- natural draft
- BTU Input Range
- 38k - 233k BTU
- Domestic Hot Water
- indirect-ready
- In Production
- Yes
- Parts Warranty
- 2-year
- Heat Exchanger Warranty
- 20-year
Specifications sourced from the manufacturer spec sheet, checked Sep 27, 2026.
Ideal For
Budget-conscious replacements of older atmospheric gas boilers in homes with a working chimney
Expert Review: Weil-McLain CGa Series 4
The Weil-McLain CGa Series 4 is a cast-iron, natural draft hot-water boiler rated at 84% AFUE, with inputs from 38,000 to 233,000 BTU/hr. It vents into a conventional chimney and can pair with an indirect water heater. The heat exchanger carries a 20-year warranty. It suits like-for-like replacements where the chimney and near-boiler piping can stay, and where upfront cost matters more than peak efficiency.
Key Features & Technology
84% AFUE cast-iron hot-water boiler
38,000-233,000 BTU/hr range
Natural draft venting into an existing chimney
Ready for an indirect water heater
20-year heat-exchanger warranty
Advantages
- Simple, proven cast-iron design with few electronics
- Often reuses the existing chimney and piping
- Wide size range fits small and large homes
Considerations
- 84% AFUE is well below condensing boilers
- Chimney usually needs inspection and may need a liner
- Not a steam boiler
Sizing & Installation Notes
Hot water boilers like the CGa Series 4 are sized from a room-by-room heat-loss calculation. We never match the old boiler's size — oversized units short-cycle, waste fuel and wear out years early.
Every Weil-McLain installation starts with a free in-home assessment covering the heat-loss calculation, venting and chimney condition, gas or oil supply sizing, and permit requirements for your town. Learn more about our boiler installation process, or see current rebate and incentive programs that may apply.
Warranty & Protection
Parts Warranty
2-year
Heat Exchanger
20-year
Our Guarantee
100% Satisfaction
All Weil-McLain boiler installations by Home+ Air & Heat include our 1-year workmanship warranty, covering labor and any installation-related issues.
Compare the Weil-McLain Lineup
| Model | Efficiency | BTU Range | Fuel | Heat Exchanger Warranty |
|---|---|---|---|---|
| CGa Series 4 (this model) | 84% AFUE | 38k - 233k BTU | natural gas/propane | 20-year |
| Ultra Series 3 | 95% AFUE | 80k - 399k BTU | — | 15 years |
| CGi Series 4 | 84% AFUE | 75k - 175k BTU | — | Lifetime |
| EG-45 | 82% AFUE | 105k - 175k BTU | — | Lifetime |
| EG Series 6/7 | 84% AFUE | 75k - 282k BTU | natural gas/propane | 10-year (EG/PEG steam) or 20-year (EG water) |
| Evergreen Pro | 95% AFUE | 110k - 399k BTU | natural gas/propane | lifetime limited |
| GV90+ | 91.9% AFUE | 70k - 175k BTU | natural gas/propane | primary (cast iron) 20-year, secondary (stainless) 5-year |
| Simplicity | 95% AFUE | 110k - 199k BTU | natural gas/propane | lifetime limited |
| Ultra Oil | 87% AFUE | 112k - 196k BTU | oil | 20-year |
| WGO/WTGO Series 4 | 87% AFUE | 98k - 357k BTU | oil | 20-year |
| AquaBalance Series 2 | 95% AFUE | 80k - 155k BTU | natural gas/propane | 10-year limited residential / 5-year limited commercial |
| CGi Series 5 | 84% AFUE | 48k - 222k BTU | natural gas/propane | 20-year residential / 10-year commercial limited transferable (CGi Series 5 sales flyer) |
| ECO Tec | 95% AFUE | 80k - 199k BTU | natural gas/propane | 12-year residential / 10-year commercial primary heat exchanger (brochure) |
| Ultra Gas Series 4 | 94.1% AFUE | 80k - 399k BTU | natural gas/propane | 12-year residential / 10-year commercial (Ultra Series 4 brochure) |
| SGO Series 4 | 85% AFUE | 133k - 357k BTU | oil | 10-year |
See the full Weil-McLain brand page for lineup context, or browse the Best Hot Water Boilers 2027 guide to compare across brands.
Frequently Asked Questions
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