Combi Wall Mount Natural Gas Boiler, 155,000 BTU

Weil-McLain AquaBalance Combi 155 Wall-Mounted Condensing Gas Boiler – Model 383100050

The Weil-McLain AquaBalance Combi 155 is a high-efficiency, wall-mounted condensing boiler designed to deliver both space heating and domestic hot water in a single, compact unit. This model operates with a 95% AFUE and is suited for residential applications where energy efficiency, footprint reduction, and on-demand hot water are required. It is shipped configured for natural gas operation and includes a field-conversion kit for liquid propane (LP).

Design & Performance Features

• Boiler Type: Combination (Space Heating + Domestic Hot Water)
• Heat Exchanger: Stainless steel, corrosion-resistant for prolonged service life in condensing applications
• AFUE: 95% (ENERGY STAR® certified)
• Input: 155,000 BTU/hr (modulating)
• Space Heating Output: 125,000 BTU/hr
• Domestic Hot Water: Integrated plate heat exchanger with output up to 4.0 GPM (ΔT dependent)
• Modulation: 5:1 turndown ratio for consistent heat delivery and improved fuel efficiency
• NOx Emissions: Low NOx (<20 ppm), compliant with South Coast Air Quality Management District (SCAQMD) Rule 1146.2

Technical Specifications

• Model: AquaBalance Combi 155 (383100050)
• DOE Heating Capacity: 144,000 BTU/hr
• Net I=B=R Rating: 125,000 BTU/hr
• Fuel Type: Natural Gas (LP conversion kit included)
• Vent Connection: 2” or 3” (PVC, CPVC, Stainless Steel, or Polypropylene)
• Vent Adapter: Factory-supplied 3-in-1 vent adapter
• Relief Valve: 30 PSI (factory-installed)
• Max Working Pressure: 50 PSI
• Dimensions: 17.7" W x 29.5" H x 12.6" D

Installation Considerations

This unit is intended for professional installation. It includes integral primary/secondary piping and a built-in circulator. Installation requires proper venting configuration, combustion calibration, and domestic water piping. The boiler must be commissioned using a combustion analyzer to validate CO₂/O₂ performance and ensure compliance with manufacturer guidelines and local code.

Clearances for service, condensate management, and gas line connection must be observed. The AquaBalance is suitable for direct-vent sealed combustion and requires intake/exhaust termination through a sidewall or roof (per manufacturer specifications).

Control & Integration

• Display: Digital interface with parameter setup, status indication, and error diagnostics
• Outdoor Reset: Included for variable setpoint control based on ambient temperature
• Pump Control: Internal system pump with dedicated terminals for DHW and heating functions

Compliance & Listings

• ENERGY STAR® certified
• CSA listed for U.S. and Canada
• ASME Section IV compliant pressure vessel
• Low NOx emissions per regional codes

Summary

The Weil-McLain AquaBalance Combi 155 (383100050) is a compact, dual-function boiler offering high-efficiency space heating and on-demand domestic hot water in residential applications. With stainless steel heat exchanger construction, integrated DHW plate exchanger, and built-in venting flexibility, it provides a streamlined solution for hydronic contractors working in limited-space environments.