Safety first: Switch off power at the breaker before removing any covers. Hot water circuits may still be pressurized.

Step 1 – Check power and breakers:
- Verify that the dedicated circuit breaker for the Nibe water heater is ON and has not tripped.
- Check any local isolator switches near the unit.
Step 2 – Reset high-limit thermostat:
- Remove the front panel and locate the high-limit safety thermostat.
- Press the reset button until it clicks.
Step 3 – Verify temperature setting:
- Ensure the setpoint temperature on the Nibe controller is not set too low (e.g. below 40 °C).
Step 4 – Check external heat source (if indirect):
- Confirm that the connected boiler or heat pump is running and that flow/return pipes to the Nibe cylinder are hot when there is demand.
Step 5 – Test immersion heater (qualified persons):
- With power off, measure resistance of the immersion heater; an open circuit indicates failure.

If you are not comfortable testing live circuits or replacing heaters, contact a qualified Nibe service technician.

Water heater produces no hot water at all; taps run cold despite power being available.

Possible Causes