Ariston Thermostat (Thermal Cut-Out) 921049

The Ariston 921049 is a thermostat supplied as a thermal cut-out for Ariston gas boilers. It is a single pole cut-out device fitted to the Comfort Indirect STI and Comfort STI appliance families, where it interrupts the boiler's control circuit when the sensed temperature exceeds the safe limit. The component is listed under thermostats within gas boiler spares.

• The boiler locks out and will not fire, with the cut-out having tripped
• The cut-out trips repeatedly after being reset, even once the appliance has cooled
• No hot water or heating is produced because the control circuit remains open
• The cut-out does not reset or shows no continuity across its terminals when tested

• Confirm the appliance model matches one of the fit lines listed above
• Check the appliance serial number against the stated serial range where one is given for your model
• Confirm the existing thermostat is a single pole cut-out and compare the terminal arrangement before ordering