Heater shows E09 and shuts down; may occur after several minutes of operation.

Safety first: Turn off power before working on plumbing or sensors. Hot water can cause burns; allow the system to cool.

• Check temperature setting: Verify that the Kripsol heater setpoint is within recommended limits (typically 26–30°C for pools, 37–40°C for spas).
• Improve flow: Clean/backwash the filter, empty pump baskets, and ensure all valves are correctly positioned to send adequate flow through the heater.
• Adjust bypass: If a Kripsol bypass kit is installed, partially close the bypass valve so more water flows through the heater, but do not over-restrict total system flow.
• Verify outlet sensor: Test the Kripsol outlet NTC sensor resistance and compare to actual water temperature. Replace the sensor if it is reading significantly higher than reality.
• Restart: After adjustments, restore power and monitor outlet temperature on the display. If E09 recurs, internal scaling or exchanger issues may be present and require professional descaling.