84.0% 8 PIN Natural Gas Induced Draft Water Boiler, Spark Ignition, Cast Iron

Weil-McLain CGi-3 Gas-Fired Water Boiler – Cast Iron, 49 MBH Input, Natural Draft

The Weil-McLain CGi-3 is a gas-fired, cast iron water boiler designed for closed-loop hydronic heating systems. Engineered for residential applications, it delivers 41,000 BTU/hr net I=B=R output with an AFUE of 84%, meeting federal efficiency requirements for non-condensing gas boilers. With a compact footprint and standard chimney venting, the CGi-3 is ideal for retrofit installations where space and flue configurations must be preserved.

Performance Overview

• Input: 49,000 BTU/hr
• DOE Heating Capacity: 43,000 BTU/hr
• Net I=B=R Rating: 37,000 BTU/hr
• AFUE: 84%
• Fuel Type: Natural gas standard; convertible to LP with field kit

Construction and Controls

• Heat Exchanger: Sectional cast iron block for long service life and thermal stability
• Ignition: Intermittent electronic ignition (spark-to-pilot)
• Safety Devices: Built-in low water cutoff, pressure relief valve, and flue spill switch
• Flue Type: Category I, natural draft venting through chimney
• Circulator: Comes with factory-mounted circulator pump

Installation and Configuration

The CGi-3 is shipped assembled with factory-installed controls and burner tray. Connections for water supply/return, gas piping, and venting are accessible from standard positions. The boiler requires a Category I flue system and should be installed by a licensed professional per local codes and manufacturer instructions. A combustion analyzer and proper draft verification are required during commissioning.

Highlights for Professionals

• Compact cabinet: suitable for basements, closets, or utility rooms
• Compatible with standard zone controls and circulator zoning setups
• Control panel includes temperature/limit controls and wiring terminal strip
• Tested and certified to ANSI Z21.13 standards for hydronic appliances

Application Notes

Designed for closed-loop, forced hot water systems. Suitable for use with baseboard, radiators, or in-floor radiant applications. Boiler must be protected against low return water temperature if used with high-mass systems or radiant loops without mixing control.

Summary

The Weil-McLain CGi-3 boiler offers a proven solution for contractors working in residential hydronic applications. Its combination of cast iron durability, straightforward service access, and dependable performance make it an ideal choice for heat-only systems requiring standard venting and a compact, robust design.