Navien Boiler: No space heat – Navien NHB-H / NFB-H

No space heat - Navien NHB-H / NFB-H on a Navien boiler: Thermostat calls for heat but the boiler does not heat the zones and shows no error code.

Homeowner with a boiler problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Applies to: Navien NHB-H and NFB-H condensing boilers

Common causes of no space heat - navien nhb-h / nfb-h

• Set temperature too low or outdoor reset / WWSD holding heat off
• Boiler off, no power or in standby
• Boiler busy with indirect DHW (DHW priority)
• Thermostat DIP switch or zone settings wrong
• Pump or zone valve not powered

How to fix no space heat - navien nhb-h / nfb-h: step by step

1. Check the space heating set temperature; with outdoor reset on, check the outdoor temperature against WWSD (default OFF) and the curve.
2. Make sure the boiler has 120 V power and is turned on with the Power button.
3. If the indirect tank is calling, space heating waits up to the DHW Priority Time (default 30 min).
4. Check DIP SW2 #7: OFF = thermostat used, ON = unused (continuous operation).
5. Check Input/Output Status: is the thermostat input seen, and are the boiler pump, zone pumps or zone valves energized?
6. Run Test Mode for the pumps and zone valves to confirm they operate; check Zone Settings (pump vs valve system) match the install.
7. Check Error History for codes that cleared on their own.
8. Press Back to reset. If still no heat, call Navien technical support 1-800-519-8794.

If the unit shows an error code, look it up: Navien Boiler codes

Models

Navien NFB-H

NFB-175HNFB-200H

Navien NHB-H

NHB-055HNHB-080HNHB-110HNHB-150H