How to Fix / Troubleshooting

Safety: Monitor system pressure and temperature; if they rise excessively, switch off the boiler.

Check pump: Confirm that the Herz circulation pump continues to run while the burner is on. Intermittent operation suggests a failing pump or relay.
Inspect sensors: Wiggle sensor cables gently (power off) and ensure all plugs are secure.
Observe controls: Watch the room thermostat or controller to see if it is removing demand prematurely.
Technician diagnosis: If the fault is intermittent and no code is shown, a Herz technician may need to log data or monitor live values.

Boiler starts normally but shuts down after a few minutes without error code

Possible Causes