A reliable three‑section cast‑iron steam boiler engineered for stable steam production, long service life, and clean, efficient oil combustion. Built on the proven Weil‑McLain Gold S4 platform, the 386701000 arrives as a factory‑packaged unit with burner installed, ensuring proper alignment, consistent ignition, and reduced installation time. Designed for natural‑draft chimney venting, it is an ideal replacement for older atmospheric steam boilers in residential one‑pipe or two‑pipe systems.
Key Features
Three‑section cast‑iron heat exchanger designed specifically for steam generation, delivering dry steam and stable system pressure.
133,000 BTU heating capacity suitable for medium‑sized homes with steam radiators or steam baseboard.
Factory‑installed oil burner matched to the boiler’s firing rate for clean, reliable combustion.
85% AFUE efficiency providing strong performance with straightforward annual maintenance.
Natural‑draft chimney venting for easy retrofit into existing flue systems.
Quiet, low‑vibration operation supported by Weil‑McLain’s combustion chamber and block design.
Service‑friendly layout with accessible burner, controls, and steam trim.
Ideal Applications
Homes with one‑pipe or two‑pipe steam systems needing a dependable, mid‑capacity oil‑fired steam boiler with a factory‑matched burner and natural‑draft venting.
