Weil-mclain 381-359-307 CGA-5 Natural Gas Cast Iron Boiler 113000 Btu Spark Ignition Series 4

Product Description

The Weil-McLain 381-359-307 is a Series 4 CGA-5 natural gas-fired cast iron hydronic boiler designed for residential and light commercial heating applications. It carries an IBR Net Output Rating of 113,000 BTU and a DOE output of 98,000 BTU, with a BTU input of 133,000, delivering reliable, efficient heat for hot water heating systems. This boiler operates at 84% AFUE, meaning it converts the vast majority of fuel into usable heat, keeping operating costs in check for building owners and facilities managers. HVAC professionals and licensed heating contractors rely on cast iron boilers like the CGA-5 Series 4 for their long service life, durability, and consistent performance in hydronic heating systems. The CGA-5 features a natural draft, silent operation design that minimizes noise during burner cycles. Stainless steel burners provide quieter ignition, improved combustion efficiency, and extended component life compared to standard burner assemblies. The spark ignition system eliminates the need for a standing pilot, reducing gas consumption and simplifying maintenance. A built-in low water cut-off function is included, adding a critical safety layer that shuts the boiler down if water level drops below safe operating thresholds. The compact footprint is designed to save valuable mechanical room or utility space. Vertical flueways and a top-cleaning design give service technicians fast, straightforward access for annual maintenance and inspections. Controls are easily accessible, reducing labor time during commissioning and service calls. The unit runs on 120-volt single-phase power and connects to a 6-inch vent. Water connections are 1 inch and the gas connection is 1/2 inch. Overall dimensions are 16 inches wide, 23-1/4 inches deep, and 57-7/8 inches tall. This boiler is backed by a 20-year heat exchanger warranty and a 2-year parts warranty, reflecting the manufacturer's confidence in the longevity of cast iron construction. Installation, commissioning, and service must be performed by a licensed heating professional in accordance with all applicable codes and manufacturer guidelines.

• Cast iron sectional heat exchanger with 84% AFUE efficiency for reliable long-term performance in hydronic heating systems
• Stainless steel burners with spark ignition for quieter operation, cleaner combustion, and reduced maintenance needs
• Built-in low water cut-off functionality and easily accessible controls for safe, efficient servicing by licensed professionals

Product Highlights

The Weil-McLain 381-359-307 CGA-5 Series 4 boiler combines cast iron durability with stainless steel burner technology and a compact design, making it a dependable choice for licensed HVAC professionals installing or replacing hydronic heating systems. The 20-year heat exchanger warranty and built-in safety features support long service intervals and confident installations.

Product Information

Standard Information

• Brand: WEIL-MCLAIN
• Manufacturer Part Number: 381-359-307

Technical Specifications

• Product Type: Boiler
• Boiler Type: Standard
• System Type: Hydronic (Water)
• Application: Heating
• Fuel Type: Natural Gas
• Ignition Type: Spark Ignition
• BTU Input: 133,000 BTU
• BTU Output: 98,000 BTU
• IBR Net Output Rating: 113,000 BTU
• DOE Rating: 113,000 BTU
• Efficiency (AFUE): 84%
• Voltage: 120V
• Phase: 1
• Vent Type: Power Vent
• Vent Size: 6 inches
• Water Connection: 1 inch
• Gas Connection: 1/2 inch
• Width: 16 inches
• Depth: 23-1/4 inches
• Height: 57-7/8 inches
• Warranty: 20 Year (Heat Exchanger) / 2 Year (Parts)