Weil-mclain 381-359-308 CGA-6 Natural Gas Cast Iron Hot Water Boiler 122000 Btu Spark Ignition Series 4

Product Description

The Weil-McLain 381-359-308 is a Series 4 CGA-6 natural gas-fired cast iron hot water boiler rated at 122,000 BTU net output. It is designed for hydronic heating systems in residential and light commercial applications. Licensed HVAC professionals rely on this boiler for its proven cast iron construction, efficient spark ignition system, and natural draft operation. The unit carries an 84% AFUE rating, meaning it converts the vast majority of fuel into usable heat. With a BTU input of 166,000 and a DOE heating capacity of 141,000 BTU, this boiler delivers reliable output for forced hot water systems. The IBR net rating of 123,000 BTU makes it well-suited for sizing hydronic heating zones in medium to large homes. Cast iron sections provide long service life and excellent heat retention, which is why this boiler type remains a preferred choice among heating contractors. Stainless steel burners deliver quieter ignition cycles, reduced wear, and more consistent combustion compared to standard burners. The CGA-6 features built-in low water cutoff functionality, a critical safety feature that protects the heat exchanger from running dry. Natural draft venting with a 6-inch vent connection keeps installation straightforward in homes with existing chimney or power vent setups. The compact footprint measures 19 inches wide by 23.25 inches deep by 60.875 inches tall, making it practical for mechanical rooms where space is limited. Controls are front-accessible, and vertical flueways allow top cleaning, so service calls are fast and efficient. The 1.25-inch water connection and 0.5-inch gas connection are standard sizes that simplify rough-in work. This unit is rated for installations up to 4,500 feet above sea level. The heat exchanger carries a 20-year warranty, with a 2-year warranty on parts. Installation, commissioning, and service must be performed by a licensed heating professional in accordance with all applicable codes and manufacturer guidelines.

• 84% AFUE natural gas cast iron boiler with spark ignition for reliable, efficient hydronic heating
• Built-in low water cutoff protection and stainless steel burners for safer, quieter, longer-lasting operation
• Front-accessible controls and top-cleaning vertical flueways for fast, straightforward service calls

Product Highlights

The Weil-McLain CGA-6 Series 4 delivers proven cast iron durability and 84% AFUE efficiency in a compact footprint, backed by a 20-year heat exchanger warranty. It is a dependable choice for licensed professionals installing or replacing hydronic heating systems in residential and light commercial settings.

Product Information

Standard Information

• Brand: WEIL-MCLAIN
• Manufacturer Part Number: 381-359-308

Technical Specifications

• Product Type: Boiler
• Boiler Series: CGA-6 Series 4
• System Type: Hydronic (Water)
• Fuel Type: Natural Gas
• Ignition Type: Spark Ignition
• Vent Type: Power Vent
• Vent Size: 6 inches
• BTU Output (IBR Net): 122,000 BTU
• IBR Rating: 123,000 BTU
• BTU Input: 166,000 BTU
• DOE Rating: 141,000 BTU
• Efficiency (AFUE): 84%
• Water Connection: 1.25 inches
• Gas Connection: 0.5 inches
• Height: 60.875 inches
• Width: 19 inches
• Depth: 23.25 inches
• Max Altitude: 4,500 feet
• Application: Heating
• Warranty: 20 Year (Heat Exchanger) / 2 Year (Parts)