Natural Gas Water Boiler for EG-55

EG-55 Natural Gas Water Boiler – Cast Iron Performance for Hydronic Heating Systems

The Weil-McLain EG-55 is a natural draft, cast iron boiler designed for hot water heating applications in both residential and light commercial environments. Manufactured in a knockdown configuration for ease of handling and transport, the EG-55 delivers a rated input of 200 MBH and an 84% AFUE, offering energy-efficient operation while meeting standard heating demands in multi-zone systems.

This model incorporates an intermittent electronic ignition system and includes a factory-supplied automatic vent damper to minimize standby losses. The heavy-duty cast iron heat exchanger is built for longevity, providing thermal mass and structural durability ideal for closed-loop hydronic systems.

Core Specifications

• Input Capacity: 200,000 BTU/hr
• AFUE: 84% (Natural Gas)
• Fuel Type: Natural Gas Only
• Ignition System: Spark Ignition with Safety Controls
• Heat Exchanger: Cast Iron, Sectional Design
• Vent Configuration: Chimney-Vented (Atmospheric)
• Control Components: Supplied with vent damper and low water cutoff

Application and Installation Notes

Designed for hot water systems, the EG-55 can support baseboard, panel radiator, and radiant floor applications. It ships as a knockdown unit requiring assembly on site. Proper setup includes attention to flue piping, circulator sizing, and control wiring. A low water cutoff is integrated to safeguard the system, and appropriate system fill and expansion tank provisions must be made to meet code.

This boiler must be installed in accordance with local and national mechanical and fuel gas codes by qualified personnel. Installation requires piping knowledge and combustion setup verification to ensure safety and performance. It is not intended for use in direct-vent or sealed combustion systems.

Notable Performance Features

• Sectional Heat Exchanger: Allows for thermal expansion while maintaining system integrity
• Automatic Vent Damper: Reduces off-cycle losses and increases overall thermal efficiency
• Knockdown Design: Easier handling in tight access installations
• Multi-Zone Compatibility: Capable of serving multiple zones with proper circulator sizing
• Maintenance Access: Service panels and accessible burner tray simplify ongoing inspection

Use Case and Suitability

The EG-55 is best suited for projects requiring mid-range heating capacities in traditional atmospheric vent systems. Its robust design and proven cast iron construction make it a strong fit for retrofit or new construction jobs where reliability and mechanical simplicity are prioritized. While service-friendly, assembly and startup require trained mechanical professionals to ensure code compliance and optimal system integration.