Heater shows E12; may be associated with very high inlet temperature or recirculation systems.

Safety: Turn off power and carefully check water temperatures to avoid scalding.

• 1. Verify plumbing: Ensure the Kospel heater’s cold inlet is connected only to cold mains water, not to a hot or mixed line.
• 2. Measure inlet temperature: Run water at the heater inlet and measure with a thermometer. Compare to the maximum inlet temperature allowed by Kospel (often around 60 °C). If exceeded, adjust upstream system.
• 3. Check mixing valves: If a thermostatic mixing valve is installed upstream, verify correct operation and settings.
• 4. Inspect inlet NTC: Confirm the sensor is properly seated and not influenced by nearby hot components. Replace if readings are clearly incorrect.

Do not operate the heater with inlet water above the specified limit; this can damage internal components.