How to Fix / Troubleshooting

Safety first: Disconnect power immediately. Allow the machine and booster to cool fully before servicing.

Verify actual temperature: Use an accurate thermometer to measure tank and rinse temperatures to confirm overheating.
Inspect heater contactor/relay: Check if the heater contactor remains closed when there is no heat call. Replace if contacts are welded.
Test temperature probe: Measure probe resistance and compare to the service chart. Replace if readings are out of range.
Check thermostat settings: Ensure mechanical thermostats are set to Insinger’s recommended temperatures and are not stuck.
High-limit function: Confirm that high-limit thermostats open at their rated temperature. Replace any that fail to open.

High temperature alarm; tank or booster temperature exceeds setpoint and E18 is displayed.

Possible Causes