HVACopedia

Navien · Tankless water heater troubleshooting

No water from hot tap - Navien NPE-2

What is going on

Nothing comes out when a hot water tap is opened.

Likely causes

  • Shut-off valves closed
  • Clogged cold water inlet filter
  • Unit frozen
  • Error code active

Check in this order

  1. Make sure the shut-off valves on the hot and cold lines at the heater are open.
  2. Clean the cold water inlet filter.
  3. If an error code shows, look it up and follow it.
  4. If frozen turn the unit off, close the gas valve, open the nearest hot tap and warm both heat exchangers with a hair dryer or portable heater; check for leaks once water flows.
  5. Prevent freezing keep power connected (freeze protection needs electricity), keep the gas on (A2 models) and drain the unit if power or gas will be off for a long time.

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

More tankless water heater guides

Related

Navien error codes · Navien tips · Calculators and reference tables

Take it to the job

All guides, error codes and tips work offline in the HVACopedia app.

Open the app

Source: Navien NPE-A2/S2 User's Information Manual (20049624A), 5.1 Solving Basic Problems, p.16; 4.6, p.15. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.