Hydronic Gas Boiler Assembly CGa-4 Natural Gas Series-3 100,000 BTU Atmospheric Chimney-Vent Hot-Water Heating Unit WM-381359074

The Hydronic Gas Boiler Assembly CGa-4 Natural Gas Series-3 100,000 BTU Atmospheric Chimney-Vent Hot-Water Heating Unit (WM-381359074) provides mid-range heating capacity for homes and light commercial spaces using atmospheric venting. Rated at approximately 100,000 BTU input with an 84 percent AFUE, the CGa-4 uses the PIDN ignition platform for reliable burner ignition and stable flame sensing. Its cast-iron heat exchanger supports long-term thermal retention, while the chimney-vent design requires proper draft conditions to prevent nuisance spill-switch trips. Technicians installing the unit should confirm chimney diameter and minimum height, ensure correct inlet combustion air, validate the spill and rollout safeties, and purge system air while setting system pressure to match the CGa-4’s supply and return piping configuration.