Warmflow High Limit Thermostat (HLT)

Description

The High Limit Thermostat is a safety device which trips out when boiler water temperature approaches 100 °C.

The most likely cause of this is poor or no circulation – check there is a heat load connected to the boiler and that the pump is functioning. Another cause of an overheat could be air in the water jacket – ensure the boiler water pressure is sufficient and that all the air has been bled out of the boiler.