Weil-mclain 381-359-362 CGI-4 Cast Iron Gas Boiler 66000 Btu Output Spark Ignition Series 5 Natural Gas

Product Description

The Weil-McLain 381-359-362 is a CGI-4 Series 5 cast iron gas-fired water boiler rated at 66,000 BTU net output for residential and light commercial hydronic heating systems. Built for licensed HVAC professionals, this boiler delivers reliable, consistent heat through a proven cast iron heat exchanger that carries a 20-year warranty. Cast iron sections are well known in the trade for their durability, thermal mass, and long service life, making this unit a trusted choice for forced hot water heating applications across a wide range of building types.

This boiler operates on natural gas and features intermittent electronic spark ignition, eliminating the need for a standing pilot light. That means lower fuel consumption at standby and fewer moving parts to service. The 381-359-362 achieves 84% AFUE, a solid efficiency rating for a standard atmospheric boiler in this class. It draws in combustion air naturally and is capable of natural draft or direct exhaust venting through a 3-inch vent connection, giving installers flexibility on the job site.

The compact footprint measures 13 inches wide, 23.25 inches deep, and 28.375 inches tall, making it easier to fit into mechanical rooms, utility closets, and tight basement installations where space is at a premium. There is no vertical draft hood and no mechanical vent damper required, which simplifies installation and reduces potential failure points over the life of the system. A built-in low water cut-off function adds an important safety layer without requiring a separate add-on component.

Water connections are 1 inch and gas connections are 0.5 inches, standard sizing that works with common supply configurations. The unit includes a 007e circulator and is rated for use up to 4,500 feet altitude. DOE heating capacity is 77,000 BTU input at 90,000 BTU gross, with an IBR net rating of 67,000 BTU. This boiler is intended for installation, commissioning, and service by licensed professionals only in accordance with applicable codes and manufacturer instructions.

• 84% AFUE efficiency with intermittent electronic spark ignition for dependable, pilot-free operation
• Cast iron heat exchanger with 20-year warranty and built-in low water cut-off for long-term reliability
• Compact design with no draft hood or mechanical vent damper required, simplifying installation in tight spaces

Product Highlights

The Weil-McLain 381-359-362 CGI-4 Series 5 delivers 66,000 BTU of net hydronic heating output through a durable cast iron heat exchanger with 84% AFUE efficiency, spark ignition, and a compact footprint suited for professional installation in residential and light commercial settings.

Product Information

Standard Information

• Brand: WEIL-MCLAIN
• Manufacturer Part Number: 381-359-362

Technical Specifications

• Product Type: Boiler
• Boiler Type: Standard
• System Type: Hydronic (Water)
• Fuel Type: Natural Gas
• Ignition Type: Spark Ignition
• BTU Output (IBR Net): 67,000 BTU
• BTU Input: 90,000 BTU
• DOE Rating: 77,000 BTU
• Efficiency (AFUE): 84%
• Vent Type: Power Vent
• Vent Size: 3 inches
• Water Connection: 1 inch
• Gas Connection: 0.5 inches
• Height: 28.375 inches
• Width: 13 inches
• Depth: 23.25 inches
• Max Altitude: 4,500 feet
• Application: Heating
• Features: 007e Circulator, Built-In Low Water Cut-Off
• Warranty: 20 years (Heat Exchanger) / 2 years (Parts)