ACV Thermostat+reset 54764009

The ACV Thermostat+reset 54764009 is a mechanical safety limit device with a manual reset, designed to protect boilers from overheating. It opens its contacts when the sensed temperature reaches the factory-set switching point of 103 °C. The thermostat features a capillary length of 1500 mm and a bulb diameter of 6 mm. It uses a two-wire connection and is compatible with ACV Prestige 32 MK2 and Prestige 50 MK2 models. The manufacturer code is 54764009.

Parts of this type are selected by switching temperature, capillary length, bulb diameter, and reset mode. When replacing, ensure the bulb makes good thermal contact with the sensing surface, and check that the capillary is free of kinks or cracks. The two-wire connection is typically normally closed, so a fault in the cable or sensor will open the safety chain.

Common failure modes include a drifting switching characteristic, which can cause nuisance trips or failure to protect, and a broken capillary, which renders the thermostat inoperative. If the thermostat trips, the system will not restart automatically due to the manual reset, requiring an engineer to press the reset button after resolving the over-temperature cause.