Navien NCB-190 Combi Boiler with Tankless Water Heater

The Navien NCB-190 is a 190,000 BTU residential combination boiler, providing both space heating (hydronic) and domestic hot water from a single appliance. Smaller-capacity sibling of the NCB-240, sized for medium-size homes (1,500-2,500 sq ft) rather than the larger NCB-240's range.

Specs: 190,000 BTU input, AFUE 95% (condensing), 5.6 GPM DHW at a 70°F rise, fully modulating burner with 5:1 turndown ratio. Built-in buffer for the DHW function. PVC condensing venting. 15-year warranty on the heat exchanger, 5-year on parts, 1-year on labor.

Combi positioning serves homes where a single appliance replacing both a boiler and a water heater fits the space and cost model. The NCB-190's smaller capacity matches medium-size hydronic loops better than the NCB-240 — appropriate sized for typical home demand without oversizing.

Right buyer: medium-size home replacing aging oil-fired boiler + separate water heater with a single high-efficiency combi unit. Typical install $7,000-$10,000 including hydronic system modifications. Wrong buyer: pure DHW applications (the NPE tankless series is the right choice), or larger homes (NCB-240 or NCB-300 are more appropriate).