Boiler displays A17, no hot water from storage tank, but heating may work

Safety: Isolate power. Cylinder water can be very hot; avoid direct contact.

Steps:

• Locate cylinder sensor: On the De Dietrich cylinder, find the sensor pocket and ensure the NTC probe is fully inserted and secured.
• Check wiring: Follow the cable back to the boiler or control unit, checking for damage or loose connections.
• Compare temperature: If the boiler display shows unrealistic cylinder temperatures, the sensor is likely faulty.

Professional help: Replacement of the cylinder sensor is straightforward but must be done with the correct De Dietrich part to ensure compatibility.