10 Best Combi Boiler of December 2025

• Rinnai i120CN - Natural Gas Condensing Boiler
• The i120CN combi condensing gas boiler model offers high volume domestic hot water delivery providing endless hot water for whole home along with the comfort of whole home heating.
• Combi models offer outdoor reset to optimize your home heating performance and features an integrated modulating pump, with an outdoor reset sensor (in the box)
• Excellent operational performance with 95% AFUE efficiency and Energy Star Most Efficient certified.
• Convenient control options with the ability to connect two zone pumps to the PCB.
• Easy parameter settings and a user-friendly interface.
• Versatile venting options including 2-inch PVC up to 65 feet.
• Quick Natural Gas (NG) to Propane (LP) gas conversions (kit included)

Rinnai

Noritz

• INDOOR installation only. Fuel Type: NATURAL GAS.
• Concentric or PVC venting option
• Up to 0.96 Energy Factor/Up to 0.92 Uniform Energy Factor
• The space-saving design allows Indoor Installation type
• Ultra low NOx emissions
• 199,000 max BTU

Rinnai

• Simultaneous domestic hot water and heating
• Superior temperature stability for domestic hot water
• Noritz accessory
• Clean burner
• Easy to install with new wall bracket

Noritz

• VOLTS:120 / PHASE:1 / EFFICIENCY:94.3% / FLUE SIZE:2"-3" DIAMETER
• MAX OPERATING PRESSURE:30 PSI(2.07 BAR) / MAX WATER TEMPERATURE:194F(90C)
• RETURN/SUPPLY WATER CONNECTION:1" / IGNITION TYPE:ELECTRONIC
• GAS CONNECTION:3/4" / GAS SUPPLY PRESSURE MIN/MAX:3.5"w.c./10.5"w.c.
• DIMS:33 1/4"H X 17 1/2"W X 14"D (INCLUDES PUMP)

GREENSTAR COMBI 151

• Endless hot water, On-demand usage, Compact, Space saving, Energy conservation
• Computerized safety features, No pilot light to have to worry about
• Safety features include freeze, overheat, surge protection, and troubleshooting diagnostic codes
• Satisfies the 2012 SCAQMD Rule 1146.2 for Ultra-Low NOx Emissions
• Primary heat exchanger utilizes commercial-grade copper alloy for 25 times better heat transfer than stainless steel, Integrated controls and power cord as standard features

TAKAGI

• Simultaneous domestic hot water and heating
• Superior temperature stability for domestic hot water
• Noritz accessory
• Clean burner
• Easy to install with new wall bracket

Noritz

• Rinnai M160CN - Natural Gas Condensing Boiler
• Flexible venting options with approved Concentric, PVC, CPVC, Stainless Steel, Polypropylene (rigid and flex), for single-pipe exhaust, room air and two-pipe systems
• Stainless steel primary boiler heat exchanger for unmatched performance and durability; Copper nickel integrated DHW plate heat exchanger
• Compact wall-mounted design saves space over traditional boilers
• Features an integrated modulating pump, and outdoor reset sensor (in the box)

Rinnai

• 94-Percent Energy efficient with stainless-steel condensing heat exchanger
• Intelligent electronic controls designed to increase energy efficiency and safety
• Third party efficiency listed by AHRI
• Up to 38-Feet of 3-Inch PVC Pipe or 5-Feet of 2-Inch PVC Pipe
• Low Nox Version

Rheem

Noritz