HVACopedia

Noritz · Tankless water heater troubleshooting

Draining to prevent freezing - Noritz EZ/NRCR

What is going on

Drain the heater when it will be unpowered or unused in freezing conditions. The unit must stay plugged in for freeze protection.

Likely causes

  • Power loss in cold weather
  • Vacant home

Check in this order

  1. Warning: Turn the heater off and let it cool first.
  2. Using the display power button off > menu > Drain Water > Start (or app: User Setting > Drain Water on).
  3. Close the water supply valve and open all hot fixtures.
  4. EZ open all drain plugs. NRCR: open drain plug A (hot side), drain plug with filter B (cold side), then C, D and E, or use the isolation valve ports.
  5. Manual draining without power close gas, run hot water over 2 minutes per unit; code 11 or 41 may show and is not a fault.
  6. Refit all plugs; if unpowered, blow remaining water out with an air compressor.
  7. Danger: when restarting, the condensate trap must refill - run the unit and confirm condensate drains within about 15 minutes.

Applies to: Noritz EZ111/EZ98/EZ71 and NRCR111/NRCR92

More tankless water heater guides

Related

Noritz error codes · Noritz 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: Noritz EZ/NRCR Owner's Guide (Rev. 10-25), Preventing damage from freezing, p.24-25. 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.