Navien Tankless Water Heater: Run test mode (fan, flow valve, venturi, pump, mixing valve)

Run test mode (fan, flow valve, venturi, pump, mixing valve) on a Navien tankless water heater: Test mode drives individual parts so you can check them one at a time.

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

Applies to: Navien NPE-A2 (built-in recirculation) and NPE-S2 condensing tankless water heaters: NPE-150S2, NPE-180A2/S2, NPE-210A2/S2, NPE-240A2/S2

How to fix run test mode (fan, flow valve, venturi, pump, mixing valve): step by step

1. Hold Menu and Back together for 3 seconds and choose 3. Test Mode.
2. Fan Motor: fan ramps from 0 to max and back, repeating.
3. Water Flow Adjust Valve: full open to full close over about 12 s, shows 0-100%.
4. Dual Venturi: on when entered, Up/Down toggles on/off.
5. Pump (A2) / Ext. Pump (S2): runs 10 s, stops 5 s, 5 times (75 s).
6. Mixing Valve (S2 only): full open to full close over about 10 s, shows 0-56%.

If the unit shows an error code, look it up: Navien Tankless Water Heater codes

Models

NPE-150S2NPE-180A2NPE-180S2NPE-210A2NPE-210S2NPE-240A2NPE-240S2