The NHB line is Navien's residential heating-only boiler. Unlike NCB and NFC combi units, NHB does NOT include built-in DHW production. To get hot water in an NHB-equipped home, pair it with an indirect water heater (a separate insulated tank with a heat-exchanger coil that uses the boiler loop to heat domestic water).
NHB lineup
| Model | BTU | Typical heating load |
|---|---|---|
| NHB-55 | 55,000 | Small home (under 1,500 sq ft) |
| NHB-80 | 80,000 | 1,500-2,200 sq ft |
| NHB-110 | 110,000 | 2,200-3,000 sq ft |
| NHB-150 | 150,000 | 3,000-4,000 sq ft |
When NHB + indirect is better than NCB combi
- Very high DHW demand — combi units share DHW priority with heat; under continuous high DHW draw, heat is paused. NHB + indirect avoids this conflict because the indirect stores hot water
- Very high simultaneous demand — large family, multiple showers, dishwasher all at once. Indirect tank handles the peak; combi struggles
- Multi-zone hydronic with significant heat load — NHB can fully focus on heat without DHW interruptions
- You already have an indirect water heater in good condition
When NCB / NFC combi is better
- Space-constrained mechanical room — combi saves the indirect tank footprint
- Lower DHW demand — household with consistent but modest hot-water use
- Lower upfront cost — combi avoids the indirect water heater purchase ($1,200-2,500 for a decent indirect)
What's an indirect water heater?
An insulated storage tank (typically 40-80 gallons) with a stainless coil inside. Boiler hot water circulates through the coil; that coil heats the domestic water in the surrounding tank. No internal burner — the heat comes from the boiler. Brands: Vaughn, Heat-Flo, Bock, Triangle Tube Phase III, Phoenix.
Hydronic install
NHB + indirect adds a DHW circuit to the standard hydronic install. The indirect ties into the boiler's primary loop with its own circulator and zone valve. The boiler treats the indirect as a "DHW zone" with priority.
Warranty
NHB: 10 years heat exchanger / 5 years parts / 1 year labor.
The indirect water heater has its own warranty (manufacturer-specific, typically 7-15 years on the tank).
Pricing
- NHB-80: $2,099-2,399
- NHB-110: $2,299-2,599
- NHB-150: $2,499-2,899
- Indirect water heater (40-80 gal): $1,200-2,500
- Combined install: $5,000-9,000
Bottom line
For most homes, NCB or NFC combi is the simpler answer — one unit, one warranty, less complex install. NHB + indirect is the right call when DHW demand is very high or when you specifically want heat and DHW to never compete.