De Dietrich 95363356 thermostat 85C

The De Dietrich 95363356 is a mechanical thermostat with a switching point of 85 °C. Parts of this type act directly on the electrical circuit, typically as a safety limit or high-limit device. When the sensed temperature reaches the set point, the thermostat opens or closes contacts to interrupt the burner operation or to signal an overheat condition. Unlike NTC sensors that report a varying resistance to the control board, a mechanical thermostat uses a bimetal or capillary element that operates a snap‑action switch at a fixed temperature. When selecting a replacement thermostat of this kind, the key parameters are the switching temperature (here 85 °C), the reset type — manual reset thermostats require a human operator to push a button after a trip, while automatic reset thermostats re‑close once the temperature drops below a differential value — and the probe form. Common probe forms include immersion pockets, clamp‑on straps, or capillary bulbs with a bulb well. Also check the electrical rating, the number of contacts (normally closed or normally open), and the cable length if the thermostat is wired remotely. Typical failures in mechanical thermostats include drifting of the switching point due to age or thermal cycling, contact welding or pitting, loss of capillary charge (in bulb‑and‑capillary types), and poor thermal contact between a clamp‑on probe and the pipe surface. When replacing, ensure the new thermostat is mounted with good thermal coupling and that the electrical connections are clean and tight. Always confirm the reset behaviour matches the original to maintain the correct safety sequencing in the burner control.