Navien Boiler: Relief valve discharging – Navien NHB-H / NFB-H

Relief valve discharging - Navien NHB-H / NFB-H on a Navien boiler: The pressure relief valve drips or discharges, or pressure climbs high when the boiler heats.

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 relief valve discharging - navien nhb-h / nfb-h

• Expansion tank waterlogged, undersized or isolated
• Make-up / pressure reducing valve over-filling
• Relief valve rating too low for the system pressure (NFB-H)

How to fix relief valve discharging - navien nhb-h / nfb-h: step by step

1. Do not plug or cap the relief valve.
2. Watch system pressure as the boiler heats; a large rise points to the expansion tank.
3. Check the expansion tank pre-charge and size, and that it is on the pump suction side and cannot be isolated.
4. Check the make-up water valve is not raising pressure above the fill setting (typical 12 psi).
5. NHB-H: system 12-30 psi with a 30 psi valve. NFB-H: 12-80 psi; if a higher-rated ASME valve (up to 80 psi) is fitted, set parameter 17 High Sys Pressure to suit.
6. Replace the relief valve if it leaks after pressure is correct.

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