Hamworthy Thermostat Roll Out 573409018

The Hamworthy 573409018 is a roll-out thermostat used on Hamworthy gas boilers. It monitors flue temperature and interrupts the burner circuit if that temperature rises beyond the safe limit, acting as a safety cut-out. It is listed within the Hamworthy thermostats range of gas boiler spares.

• The boiler locks out and will not fire, with the reset sequence failing to clear the fault.
• Repeated lockouts shortly after the burner lights, pointing to a thermostat that has tripped or failed open circuit.
• No continuity across the thermostat terminals when the flue is at normal operating temperature.
• The thermostat has tripped and will not reset, or the reset mechanism feels loose or damaged.
• Visible heat damage, discolouration or a cracked body on the thermostat.

• Confirm the boiler model against the manufacturer's parts list to verify this part number applies.
• Check the existing thermostat's part number and terminal arrangement before removal.
• Inspect the flue and heat exchanger for the underlying cause of any overheat trip, as the thermostat may be a symptom rather than the fault.
• Isolate the appliance and follow the manufacturer's instructions for safe access and testing.