ACV Thermostat TU-L-DT A1004760

The ACV A1004760 (type TU-L-DT) is a mechanical overheat safety thermostat used in Prestige V14 boilers. It operates by direct switching with a liquid-filled capillary bulb and a snap-action switch. The temperature range is 10–85 °C, the capillary is 3000 mm long, and the bulb has a diameter of 6 mm. When the bulb temperature exceeds the set point, the internal contacts change state to cut off the circuit.

Such thermostats are selected by matching the temperature range, capillary length, bulb diameter, switching function (normally open or closed), and reset method. The bulb is typically mounted in an immersion pocket or placed directly in the flow. Before ordering, measure the existing bulb dimensions and capillary length, and verify the switching function and reset type.

Common failure modes include a drifting switching point, a broken capillary or bulb, or a loose connection between the bulb and the pipe. A drifting switching point may cause the boiler to cut off too early or not at all. A broken capillary or bulb stops the thermostat from switching, while a loose connection can lead to intermittent operation.