Water heater provides only lukewarm water; temperature at taps is lower than setpoint and drops quickly.

Safety first: Beware of scalding when increasing temperature settings. Use a thermometer at a tap to verify final temperature.

• Step 1 – Check setpoint:
  • On the Nibe controller, verify that the hot water setpoint is typically 50–60 °C.
• Step 2 – Inspect mixing valve:
  • Locate the thermostatic mixing valve on the hot outlet.
  • Ensure it is not turned to a very low setting; adjust gradually and test.
• Step 3 – Check heater operation:
  • Confirm that the immersion heater or external heat source runs long enough to heat the tank.
  • Listen for heater relay clicks and feel the heater area for warmth (without touching live parts).
• Step 4 – Consider descaling:
  • In hard water areas, arrange for professional descaling of the immersion heater and coil if performance has degraded over time.

If the problem persists, a technician should check coil flow rates and sensor calibration.