Gas Boiler EVG 399 High Efficiency Condensing 399 MBH 10 to 1 Modulating Stainless Steel Heat Exchanger WM-383900002

The Gas Boiler EVG 399 High Efficiency Condensing 399 MBH 10 to 1 Modulating Stainless Steel Heat Exchanger (WM-383900002) delivers a 399,000 BTU input with approximately 383,000 BTU output and a verified 96.5 percent AFUE, providing high-capacity, low-NOx performance for commercial and large residential hydronic systems. Its stainless steel fire-tube heat exchanger supports true condensing operation at low return water temperatures, while the 10 to 1 turndown modulating gas valve maintains smooth heating output and efficient fuel use. The boiler operates on 120 volt single-phase power, includes a fully integrated control platform with onboard diagnostics, and supports direct venting in 4 inch PVC, CPVC or polypropylene. System connections include a 1 1/2 inch supply and return, a 3/4 inch gas inlet, and condensate drainage sized for high-efficiency operation. Technicians benefit from primary and secondary piping compatibility, field-serviceable ignition and sensor assemblies, easy-access cabinet design, and a durable heat exchanger engineered for long-term reliability in high-demand hydronic loops, multifamily systems and light commercial buildings.