Ultra 299 Series High Efficiency Natural Gas Boiler, 299,000 BTU

Weil-McLain Ultra 299 Series 4 High-Efficiency Gas Boiler

The Weil-McLain Ultra 299 is a high-efficiency, condensing gas boiler engineered for residential and light commercial hydronic heating applications. Part of the Ultra Series 4 line, this unit delivers up to 92.5% AFUE and is built with advanced materials and proven combustion technology to ensure long-term performance in demanding environments.

Utilizing a cast aluminum heat exchanger treated with a nanotechnology-based coating, the Ultra 299 is optimized to resist corrosion and reduce particulate accumulation. This contributes to enhanced thermal transfer efficiency and reduced service intervals, making it a reliable solution for contractors prioritizing performance and lifecycle cost control.

Professional-Grade Advantages

• Efficient Condensing Technology: 92.5% AFUE rating maximizes energy utilization and supports compliance with high-efficiency rebate programs.
• Material Resilience: Engineered heat exchanger with nanocoating resists scale buildup and supports consistent operation under variable load conditions.
• Flexible Installation: Approved for direct vent and room air configurations using PVC, CPVC, or polypropylene venting (4" dia.).
• Dual Fuel Capability: Factory configured for natural gas with field-convertible LP kit included for application flexibility.
• Compact Dimensions: Measures 47-3/4" H × 22-13/16" W × 22-1/8" D, facilitating installations in mechanical rooms with limited clearance.

System Specifications

• Input Capacity: 299,000 BTU/hr
• Net IBR Rating: 234,000 BTU/hr
• Water Connections: 1-1/4" NPT
• Gas Connection: 3/4" NPT
• Vent Connection: 4" dia.

Application Considerations

Due to its advanced control logic and specific venting and gas supply requirements, the Ultra 299 should be installed by licensed professionals familiar with condensing boiler systems and combustion analysis. Proper commissioning is essential to ensure optimal modulation and safe operation in accordance with ASME and local mechanical codes.

Key Use Cases

• High-efficiency retrofits in existing hydronic systems
• New residential construction targeting energy performance certifications
• Multi-zone radiant or baseboard systems requiring precision modulation

Control and Modulation

The Ultra 299 features a modulating stainless steel premix burner and advanced control board supporting outdoor reset and multiple zone integration. This allows tighter temperature control and load matching, reducing fuel consumption and increasing occupant comfort.

Ultra Series 4 Model 299 – High-Efficiency Gas-Fired Condensing Boiler

The Weil-McLain Ultra 299 is a gas-fired, condensing hot water boiler designed for high-efficiency residential or light commercial hydronic heating systems. Rated at 299,000 BTU/hr input, this model achieves up to 92.5% AFUE and is equipped with a corrosion-resistant stainless steel fire tube heat exchanger. The boiler is field-configurable for either natural gas or LP operation and is compliant with ASME Section IV for pressure vessels.

The Ultra Series 4 platform features advanced combustion controls, outdoor reset logic, and modulating burner operation to improve efficiency under part-load conditions. This boiler is suitable for wall-mount or floor-standing installation when used with the appropriate bracket or base kit.

System and Mechanical Specifications

• Input Capacity: 299 MBH (Natural or Propane)
• Net I=B=R Water Rating: 234 MBH
• Efficiency: 92.5% AFUE (DOE-rated)
• Heat Exchanger: Fire-tube, stainless steel, coated with factory-applied non-stick treatment to mitigate fouling and scale buildup
• Fuel Type: Field convertible between natural gas and LP (conversion kit included)
• Ignition System: Direct spark ignition with integrated safety lockout
• Operating Pressure: Max 50 psi; relief valve factory-set at 30 psi
• Water Connection: 1-1/4” NPT
• Gas Connection: 3/4” NPT
• Vent Size: 4” (PVC, CPVC, or polypropylene approved; concentric or twin-pipe configuration supported)

Control & Integration Features

• Boiler Control: Advanced digital control with user interface and diagnostic display
• Outdoor Reset: Standard, with user-programmable curve and warm weather shutdown
• Modulation: 5:1 turndown ratio for improved part-load efficiency
• DHWP Capability: Indirect water heater prioritization supported via internal control board
• Field Interlocks: Terminals provided for external control, pump control, and safety circuits

Cabinet Dimensions

• Height: 47-3/4”
• Width: 22-13/16”
• Depth: 22-1/8”

Installation Guidelines

The Ultra 299 must be installed by a licensed mechanical contractor in accordance with national fuel gas code (NFPA 54), local jurisdictional requirements, and Weil-McLain’s installation manual. Proper combustion air supply, condensate drainage, venting configuration, and hydronic piping layout are critical to performance. Ensure clearances are maintained for service access. All venting must be UL-listed and sized appropriately per the boiler’s rated input and equivalent pipe length.

Professional Application Use

This boiler is suitable for hydronic baseboard, panel radiator, radiant floor, and fan coil heating systems. It can be used in multi-zone residential applications or small commercial systems with a compatible primary/secondary piping layout. The modulating burner provides fuel savings during partial load operation, and the fire-tube heat exchanger simplifies maintenance access from the front panel.