De Dietrich 200001951 servomotor STA3 B1 37/6

This servomotor, listed under the De Dietrich brand with catalogue article 336.712.002 and manufacturer code 200001951, is an actuator of the type used to position air dampers or mixing valves in industrial heating systems. Actuators of this class translate a control signal into rotary motion, typically a 90° or 180° angle, to regulate airflow or water flow. They are selected by required torque, running time, control signal type (three‑point, 0–10 V, or on/off), shaft or coupling pattern, angle of rotation, and the presence of integral auxiliary switches. The specific values for these parameters are not stated here, so the part must be matched to the existing application by cross‑referencing the existing actuator’s specifications or consulting the appliance documentation. In a boiler or burner system, such a servomotor drives the air damper on the combustion fan or the butterfly valve on the gas train. It may also operate a three‑way or four‑way mixing valve that diverts or blends water flow between heating circuits and domestic hot water. When replacing a defective unit, common failure modes include a stripped gear train, a failed end‑switch, or a seized valve stem after a prolonged standstill period. Ensure the replacement actuator matches the control signal of the burner control board and that the mechanical interface (shaft size, coupling, mounting holes) is identical to the original. If auxiliary switches are used for proof‑of‑position, confirm their function and wiring.