Boiler displays E06; domestic hot water (DHW) temperature is not regulated correctly

Safety first: Disconnect power and close the cold water supply to the boiler before working on DHW components.

Steps to check:

• Locate the DHW sensor: On Kospel combi or indirect systems, the DHW NTC is usually inserted into a sensor well on the DHW tank or attached to the plate heat exchanger.
• Inspect and clean: Remove the sensor carefully. If it is covered with limescale, clean it with a descaling solution suitable for potable water components. Rinse thoroughly.
• Check wiring: Inspect the cable for damage and ensure the connector is firmly attached to the control board.
• Resistance measurement: Measure the sensor resistance and compare with Kospel specifications. Replace the sensor if readings are out of range.
• Reassemble and test: Reinsert the sensor fully into the well, restore water and power, then test DHW operation. Confirm that E06 is cleared and temperatures are stable.

When to call a technician: If the DHW circuit is heavily scaled or the sensor well is corroded, professional service may be required.