Siemens Actuator for air dampers and mixing valves SQN31.402A2700

The Siemens SQN31.402A2700 actuator, type designation 3012345, is intended for air dampers and mixing valves. Its operating principle is rotary movement, converting a control signal into mechanical rotation to position the attached damper or valve. The motor receives a signal from the burner control or a separate controller.

When replacing an actuator of this kind, key parameters to match are torque, running time, control signal type, and mechanical interface (shaft diameter, coupling pattern, and angle of rotation). For mixing valves, the actuator motor is usually separate from the valve body, so the drive pattern and torque must correspond to the valve. Always verify the replacement unit's electrical ratings and interface against the original before installation.

Common failure modes for actuators of this kind include stripped gear trains, failed end switches, or a seized valve stem after prolonged inactivity, particularly in seasonal systems. If the damper or valve does not move correctly, inspect the gear train, end switches, and valve stem for these issues.