Natural GAS Boiler, 233 MBH, 87% AFUE, Series 3

Williamson GWA-233 Series 3 Gas-Fired Water Boiler – Atmospheric Cast Iron Unit with Integrated Venting Efficiency

The Williamson GWA-233-N-T-S3-W is a gas-fired, cast iron water boiler engineered for residential and light commercial hydronic heating systems. With a DOE heating capacity of 194,000 BTU/hr and a net I=B=R rating of 169,000 BTU/hr, this boiler is sized to support medium to large applications requiring consistent hot water distribution and proven atmospheric reliability.

This model is part of the GWA Series 3 line and incorporates an intermittent ignition system, an automatic vent damper, and stainless steel burners for improved thermal performance and combustion durability. It is designed for use with natural gas and is non-condensing, making it compatible with standard Category I chimney venting systems.

System Highlights

• Input: 233,000 BTU/hr
• DOE Heating Capacity: 194,000 BTU/hr
• Net I=B=R Rating: 169,000 BTU/hr
• AFUE: 84.0%
• Fuel: Natural Gas

Construction and Components

• Heat Exchanger: Cast iron sectional block construction for long-term structural integrity
• Burners: Stainless steel atmospheric burners with reliable ignition and long service life
• Ignition: Intermittent electronic pilot ignition with flame sensor
• Jacket: Heavy-gauge steel with thermal insulation to minimize jacket loss
• Damper: Factory-installed automatic vent damper to reduce standby losses

Design and Serviceability

• Vent Type: Atmospheric draft; compatible with Category I chimney venting
• Flue Baffles: Installed to optimize heat transfer across heat exchanger surfaces
• Access Panels: Front-facing panel allows straightforward burner and control access
• Combustion Air: Drawn from surrounding space; ensure adequate ventilation per code

Installation Requirements

This unit is intended for use in closed-loop water systems with standard expansion tank and circulator pump configurations. Installation must conform to local mechanical, gas, and electrical codes. Proper venting through a lined masonry chimney or approved Type B gas vent is required. Clearances must be maintained for service access and combustion air flow.

Application Suitability

• Retrofit boiler replacement in residential buildings with existing hot water radiation
• Multi-zone hydronic systems using baseboard, panel radiators, or radiant manifolds
• Light commercial buildings where non-condensing, chimney-vented equipment is preferred

Warranty Coverage

• Heat Exchanger: 20-year limited warranty
• Parts: 1-year limited warranty