WGO-5R - 128,000 BTU Output Cast Iron Gold Oil Boiler - Series 4 (Burner is not included)

Weil-McLain WGO-5R Oil-Fired Water Boiler – 128,000 BTU, Water-Only Configuration

The Weil-McLain WGO-5R is a high-performance, oil-fired cast iron boiler designed for closed-loop hot water heating systems. This Series 4 model features a water-only configuration (no tankless coil or cover plate), making it ideal for installations requiring dedicated hydronic heating. Rated at 128,000 BTU/hr DOE heating capacity, the WGO-5R is well-suited for mid-sized residential or light commercial applications.

Engineered for Demanding Hydronic Systems

• Net I=B=R Water Rating: 111,000 BTU/hr
• DOE Heating Capacity: 128,000 BTU/hr
• Combustion Efficiency: 86.3% (AFUE ratings vary by burner selection)
• Fuel: #2 Heating Oil

Design and Serviceability Features

• Heat Exchanger: Cast iron, three-pass design with full chamber access via swing-away burner door and quick-open top
• Flue Outlets: Dual flue configuration (rear or top vent) supports multiple venting arrangements without additional field kits
• Circulator: Pre-wired factory-mounted circulator with integral service switch
• Recessed Target Wall: Protects against abrasion from flue brushes during maintenance
• Working Pressure: 50 PSIG maximum; hydrostatically tested to 100 PSIG

Installation Considerations

The WGO-5R is shipped partially assembled with burner sold separately. It requires connection to an oil supply, flue system, and closed-loop hydronic piping. Burner configuration, barometric damper setup, and proper draft verification are essential for optimal operation. Boiler must be installed by a qualified contractor per Weil-McLain instructions and applicable code.

Application Notes for Contractors

• Suitable for fin-tube baseboard, cast iron radiators, radiant manifolds, or air handlers
• Ideal for retrofit applications where tankless domestic hot water is not required
• Meets ASME boiler code; includes pressure relief valve, temperature/pressure gauge, and limit controls

Warranty

• Heat Exchanger: 20-year limited warranty
• Parts: 2-year limited warranty (excludes burner components if field-selected)

Summary

The WGO-5R provides robust, oil-fired water heating performance in a simple, service-friendly design. With dual venting options, reliable cast iron construction, and no unnecessary domestic components, it's a solid choice for contractors seeking a dependable boiler for hydronic-only heating loads. Field-proven and supported by one of the industry's most established manufacturers, the WGO-5R is built to perform season after season.