Siemens SSA81U 3 Position Zone Valve Actuator

Siemens SSA81U Zone Valve Actuator is a 24 V AC electronic actuator for Siemens 599 Series zone valves, compatible with 2-way and 3-way valve bodies. It provides three-position floating control (3P) and is normally closed (NC) in NSR (non-spring return) configuration, with 2.5 m leads for straightforward wiring. This actuator positions zone valves in hydronic heating and cooling systems, including boilers and radiant floor heating, enabling three selectable positions as commanded by compatible control signals, and serves as a direct replacement for 599-series actuators mounted on Siemens valve bodies. The 24 VAC coil accepts standard HVAC control circuits or building automation signals that provide a three-position input; the unit's fixed connection scheme and lead length simplify field service and installation in mechanical rooms.