EVG 299 - 243,000 BTU Output Evergreen High Efficiency Condensing Gas Boiler (Natural Gas or Liquid Propane)

Weil-McLain Evergreen® 299 – High-Efficiency Condensing Gas Boiler (Model 383900001)

The Weil-McLain Evergreen® 299 is a floor-standing, high-efficiency, modulating condensing boiler built for residential and light commercial hydronic heating systems. Designed with a stainless steel fire tube heat exchanger, this unit delivers a thermal input capacity of 299,000 BTU/hr and 95% AFUE, making it suitable for large heating loads requiring compact, serviceable, and scalable equipment.

The Evergreen 299 supports field-convertible natural gas or propane operation and includes a built-in control platform designed for single-unit and multi-boiler applications. Its integrated diagnostics, high turndown ratio, and flexible configuration make it a practical choice for complex or zoned heating systems.

Performance and Design Features

• Stainless Steel Heat Exchanger: Fire tube configuration provides high corrosion resistance and long-term thermal efficiency.
• Modulation Capability: 10:1 turndown ratio for consistent output under varying load conditions.
• Cascade Control: Onboard controls support up to 8 boilers with lead-lag rotation, auto redundancy, and combined outputs up to 2.4 million BTU/hr.
• ZoneStacking® Technology: Enables control of up to 24 heating zones from a single boiler interface without external zone controls.
• Direct Vent Design: Compatible with PVC, CPVC, and polypropylene venting materials for up to 100 feet of equivalent vent length.
• Quiet Operation: Fully insulated cabinet and modulating fan assembly reduce mechanical noise output.

Technical Specifications

• Model: Evergreen® 299 (383900001)
• Input: 299,000 BTU/hr
• DOE Heating Capacity: 278,000 BTU/hr
• Net I=B=R: 242,000 BTU/hr
• AFUE: 95%
• Fuel Type: Natural Gas or Liquid Propane (field convertible)
• Heat Exchanger: Stainless steel, fire tube
• Venting: Direct vent, sealed combustion
• Maximum Vent Length: Up to 100 ft (varies with material and diameter)
• Installation Orientation: Floor-standing (wall-mounting not applicable for this model)
• Control Interface: Digital display with integrated diagnostics, cascade logic, and I/O configuration

Installation Parameters

The Evergreen® 299 is intended for installation by licensed HVAC professionals familiar with condensing hydronic systems. Installation requires proper vent sizing, gas pressure adjustment, and condensate drainage. The system’s electrical and piping configurations must meet local mechanical code and be installed according to Weil-McLain's engineering documentation. The unit includes support for indirect DHW tank integration with domestic hot water priority and zone control logic.

Certifications & Compliance

• Certified to ANSI Z21.13/CSA 4.9 for gas-fired low pressure steam and hot water boilers
• Meets ENERGY STAR® criteria
• Low NOx (<20 ppm) – compliant with SCAQMD Rule 1146.2
• ASME Section IV stamped heat exchanger

Application Summary

The Evergreen® 299 is well-suited for large residences, multi-family dwellings, and light commercial applications such as schools, offices, or assisted living facilities. With a high-efficiency design, built-in cascade functionality, and field-serviceable components, this model supports new installations or retrofits where consistent hydronic output, zoning flexibility, and integration with modern controls are required.