Boiler shows E07 and will not start; display may show abnormal supply voltage indication

Safety first: Turn off the main breaker feeding the boiler before inspecting electrical connections.

Steps to check:

• Verify mains voltage: Have a qualified person measure the voltage at the boiler supply terminals. Compare with the rated voltage on the Kospel nameplate (e.g., 230 V ±10%).
• Inspect terminal block: Remove the front cover and check the incoming power terminal block for loose screws, discoloration, or signs of overheating. Tighten connections to the manufacturer’s torque specification.
• Check neutral and earth: Ensure that neutral and earth conductors are correctly connected and secure.
• Eliminate extension leads: The boiler must be connected directly to a dedicated circuit, not via extension cords or multi-socket adapters.
• Reset and monitor: Restore power and reset the boiler. If E07 persists with correct supply voltage, the internal power supply or control board may be defective.

When to call a technician: Any work involving live mains measurements or replacement of the power supply board should be done by a licensed electrician or Kospel service technician.