Gas-Fired Water Boiler, 119K BTU, 84% AFUE, Series 3

Williamson GWI-119 Series 3 – Induced Draft Cast Iron Gas-Fired Water Boiler

The Williamson GWI-119-N-T-S3-W is a natural gas-fired, hot water boiler built for residential hydronic heating systems requiring dependable performance and non-condensing operation. This Series 3 unit offers 119,000 BTU/hr input with an 84% AFUE rating, making it a suitable choice for systems seeking balanced efficiency and proven cast iron construction.

This boiler features an induced draft fan to stabilize combustion air flow and venting characteristics. It comes standard with an automatic vent damper, electronic intermittent ignition, and a factory-installed circulator and service switch, streamlining installation and reducing field labor time. The GWI-119 is designed for use with Category I venting and operates as a sealed combustion system for controlled, efficient operation.

Technical Specifications

• Input: 119,000 BTU/hr
• DOE Heating Capacity: 101,000 BTU/hr
• Net I=B=R Water Rating: 88,000 BTU/hr
• AFUE: 84.0%
• Fuel: Natural Gas
• Ignition: Intermittent electronic ignition system
• Draft Type: Induced draft with fan-assisted venting
• Vent Size: 4” diameter
• Construction: Cast iron heat exchanger with stainless steel burners

Performance and Design Features

• Heat Exchanger: Cast iron block rated for long-term service and stable thermal transfer
• Combustion: Fan-assisted induced draft maintains combustion efficiency and consistent flue gas flow
• Vent Damper: Automatic vent damper included to reduce standby losses during off cycles
• Burners: Stainless steel atmospheric burners for consistent ignition and combustion stability
• System Trim: Includes circulator, service switch, and factory-wired junction box

Installation Requirements

The GWI-119 is intended for use in closed-loop hydronic heating systems with adequate flow and expansion capacity. Venting must comply with Category I specifications using 4" Type B gas vent or lined masonry chimney. Installers must verify combustion air availability, electrical code compliance, and water quality prior to startup. The unit must be installed by qualified mechanical contractors per Williamson’s installation manual and applicable local codes.

Typical Applications

• Residential baseboard and panel radiator heating
• Multi-zone hydronic heating with circulator zoning
• Projects requiring fan-assisted Category I venting

Warranty Coverage

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