Weil-mclain 381-359-306 CGA-4 Natural Gas Water Boiler 73000 Btu Spark Ignition Series 4

Product Description

The Weil-McLain 381-359-306 is a Series 4 CGA-4 cast iron natural gas hydronic water boiler rated at 73,000 BTU net output. It is designed for residential and light commercial heating applications where reliable, long-lasting performance is required. HVAC professionals and heating contractors choose this boiler for its proven cast iron construction, efficient spark ignition system, and straightforward serviceability. The unit operates on natural gas and delivers an 84% AFUE efficiency rating, making it a dependable choice for forced hot water heating systems. The DOE heating capacity is rated at 85,000 BTU, and the IBR net output is 74,000 BTU, with a BTU input of 100,000. The CGA-4 features stainless steel burners that provide quieter ignition, extended service life, and improved combustion performance compared to standard burner assemblies. A Unity-CI boiler control with a text-based display screen allows technicians to monitor and adjust operation with ease. The natural draft design means silent operation with no draft inducer motor to maintain or replace. Built-in low water cut-off functionality is included, reducing the need for additional external safety components and simplifying the overall installation. The compact footprint measures 13 inches wide, 23-1/4 inches deep, and 54-3/8 inches tall, helping installers fit the unit into tight mechanical spaces. The gas connection is 1/2 inches and the water connection is 1 inches. Flueways are vertical and accessible from the top, making annual cleaning and maintenance fast for licensed technicians. The 5-inch vent size accommodates standard venting configurations. Weil-McLain backs this boiler with a 20-year heat exchanger warranty and a 2-year parts warranty, supporting long-term system reliability for building owners and contractors alike.

• Cast iron sectional heat exchanger with stainless steel burners for extended durability and quiet operation
• Unity-CI text-based boiler control with built-in low water cut-off for simplified installation and diagnostics
• 84% AFUE natural gas efficiency with 73,000 BTU net output and easy top-access serviceability

Product Highlights

The Weil-McLain 381-359-306 CGA-4 Series 4 delivers reliable hydronic heating with cast iron construction, spark ignition, and an accessible control system built for professional installation and long-term service. Its compact design and built-in safety features make it a practical choice for residential hot water heating replacements and new installations.

Product Information

Standard Information

• Brand: WEIL-MCLAIN
• Manufacturer Part Number: 381-359-306

Technical Specifications

• Product Type: Boiler
• Boiler Type: Standard
• System Type: Hydronic (Water)
• Fuel Type: Natural Gas
• Ignition Type: Spark Ignition
• BTU Output: 73,000 BTU
• BTU Input: 100,000 BTU
• IBR Rating: 74,000 BTU
• DOE Rating: 85,000 BTU
• Efficiency: 84% AFUE
• Application: Heating
• Vent Type: Power Vent
• Vent Size: 5 inches
• Gas Connection: 1/2 inches
• Water Connection: 1 inches
• Height: 54-3/8 inches
• Width: 13 inches
• Depth: 23-1/4 inches
• Warranty: 20 Year (Heat Exchanger) / 2 Year (Parts)