Product Description
The Weil-McLain 381-359-361 is a CGI-3 Series 5 cast iron gas-fired hydronic water boiler designed for residential and light commercial heating applications. It delivers 43,000 BTU output with a spark ignition system and comes paired with a Taco 007e circulator pump, making it a complete and ready-to-install heating solution for licensed HVAC professionals. The unit runs on natural gas and produces 58,000 BTU of input energy, achieving a steady 84 percent efficiency rating that meets standard performance expectations for cast iron boilers in forced hot water systems. The DOE heating capacity rating stands at 49,000 BTU, and the IBR rating is confirmed at 43,000 BTU, giving installers the verified performance data needed for load calculations and system design. Cast iron heat exchangers are known for their durability, heat retention, and long service life. This boiler uses that proven construction and adds an insulated steel jacket to reduce standby heat loss and keep the unit running efficiently. Venting is handled through a Type B vent connected to a chimney, using a 3-inch vent connection. The gas supply connects at 1/2 inches and the water supply and return connect at 1 inch. The boiler measures 10 inches wide, 23 and 3/8 inches tall, and 23 and 1/4 inches deep, fitting into standard mechanical room footprints common in residential and small commercial builds. This is a standard boiler configuration operating within a hydronic water heating system, making it compatible with baseboard radiators, radiant floor systems, and other hot water distribution setups. The Weil-McLain CGI-3 Series 5 carries a 20-year warranty on the heat exchanger and a 2-year warranty on parts, reflecting the long-term reliability built into cast iron boiler design. This unit must be installed, commissioned, and serviced by a licensed heating professional in accordance with applicable codes and manufacturer instructions.
- 43,000 BTU output with 58,000 BTU input and 84 percent efficiency for reliable hydronic heating
- Cast iron heat exchanger with insulated steel jacket for long-lasting performance and reduced standby heat loss
- Spark ignition system with Taco 007e circulator included, Type B chimney vent, natural gas fuel
Product Highlights
The Weil-McLain 381-359-361 CGI-3 Series 5 is a complete cast iron hydronic boiler package with spark ignition, a Taco 007e circulator, and a 20-year heat exchanger warranty. It is built for licensed HVAC professionals installing natural gas hot water heating systems in residential and light commercial settings.
Product Information
Standard Information
-
Brand: WEIL-MCLAIN
-
Manufacturer Part Number: 381-359-361
Technical Specifications
-
Product Type: Boiler
-
Boiler Type: Standard
-
System Type: Hydronic (Water)
-
Fuel Type: Natural Gas
-
Ignition Type: Spark Ignition
-
BTU Input: 58,000
-
BTU Output: 43,000
-
IBR Rating: 43,000 BTU
-
DOE Rating: 49,000 BTU
-
Efficiency: 84%
-
Vent Type: Type B Vent (Chimney)
-
Vent Size: 3 inches
-
Gas Connection: 1/2 inches
-
Water Connection: 1 inches
-
Width: 10 inches
-
Height: 23 and 3/8 inches
-
Depth: 23 and 1/4 inches
-
Warranty: 20 Year (Heat Exchanger) / 2 Year (Parts)
