Weil-McLain CGi Series 4
Model Number: CGi-4
Reliable cast iron hot water boiler ideal for multi-zone Long Island colonials.
Technical Specifications
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
- CGi-4
- Efficiency (AFUE)
- 84%
- Boiler Type
- Hot Water Boiler
- BTU Input Range
- 75k - 175k BTU
- In Production
- Yes
- Parts Warranty
- 2 years
- Heat Exchanger Warranty
- Lifetime
Specification source not yet linked — figures are being verified against manufacturer data.
Ideal For
Traditional hot water baseboard systems in 2,000-3,500 sq ft homes
Expert Review: Weil-McLain CGi Series 4
The Weil-McLain CGi Series 4 is the modern evolution of cast iron hot water boilers. With 84% AFUE and proven cast iron construction, it delivers reliable heat for Nassau County homes where efficiency isn't the only priority—longevity and parts availability matter too.
Why the CGi Remains Popular on Long Island
The CGi Series 4 uses the same cast iron section design that has made Weil-McLain famous for over a century. These boilers routinely last 30-40 years with basic maintenance. The lifetime heat exchanger warranty reflects Weil-McLain's confidence in their core technology.
Best Applications
The CGi excels in older Long Island homes with existing hot water baseboard or radiant systems. It handles the varying water temperatures and flow rates of complex multi-zone configurations without the electronic complexity of condensing units. Popular in Garden City, Rockville Centre, and Manhasset renovations where homeowners want proven reliability.
Installation Advantages
Unlike condensing boilers, the CGi vents into standard masonry chimneys—no PVC venting or condensate neutralizers required. For homes with functional brick chimneys, this simplifies installation and reduces cost. The cast iron sections are heavy but field-repairable: individual sections can be replaced without scrapping the entire boiler.
Cost Considerations
The CGi costs less upfront than condensing alternatives, but doesn't qualify for PSEG efficiency rebates due to its 84% AFUE. For homeowners prioritizing lowest installed cost with proven reliability, the CGi delivers. Annual operating costs run 10-15% higher than condensing models.
Key Features & Technology
Cast iron durability
Compact pin-type design
Easy maintenance access
Side wall venting option
Proven reliability since 1881
Advantages
- Lifetime heat exchanger warranty on cast iron
- Uses existing masonry chimney - no PVC venting
- Proven 30-40 year lifespan
- Individual sections field-repairable
- Simpler controls with fewer electronics
- Lower upfront cost than condensing models
Considerations
- 84% AFUE doesn't qualify for PSEG rebates
- Higher annual operating costs than condensing
- Heavy cast iron may complicate basement access
- Less efficient than modern alternatives
Sizing & Installation Notes
Hot water boilers like the CGi 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, and gas or oil supply sizing. Learn more about our boiler installation process, or see current rebate and incentive programs that may apply.
Warranty & Protection
Parts Warranty
2 years
Heat Exchanger
Lifetime
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 |
|---|---|---|---|---|
| CGi Series 4 (this model) | 84% AFUE | 75k - 175k BTU | — | Lifetime |
| Ultra Series 3 | 95% AFUE | 80k - 399k BTU | — | 15 years |
| 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 |
| CGa Series 4 | 84% AFUE | 38k - 233k BTU | natural gas/propane | 20-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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