Siemens Building Technology S55155-A109 3-Position Fail Safe Powermite MT Series Actuator
The Siemens S55155‑A109 3‑Position Fail‑Safe Powermite MT Series Actuator is a 3-position, 24 VAC floating control valve actuator with a fail-safe spring return. It drives compatible MT Series HVAC control valves by positioning the valve stem based on the control signal, regulating fluid flow in heating and cooling circuits. Used in air handlers, chilled beams, fan coils, and other HVAC terminal units, it enhances precise zone control, improves energy efficiency, supports reliable system responses, and increases overall comfort and performance in building climate systems.