HERZ 1771251 is a linear electric actuator designed for automatic operation of HERZ 4037 series 3-way mixing and diverting globe valves in heating, cooling and HVAC systems. The actuator moves the valve stem with a positioning force of 500 N, allowing automatic control of the heating or cooling medium according to commands from a heating controller or building-management system.

The supply voltage is 24 V AC ±20%, 50–60 Hz. HERZ 1771251 is designed for operation with controllers featuring a switching output. It is the 24 V switching-control version rather than the proportional 0–10 V version. The 0–10 V control and position-feedback functions belong to HERZ 1771211.

The actuator has an 8 mm stroke, a full operating time of 120 seconds and a positioning force of 500 N. Minimum response time is 100 ms. Power consumption is specified as 1.5 VA both during operation and at standstill.

The actuator incorporates a synchronous electric motor, magnetic coupling and a maintenance-free gearbox. The gearbox can be disengaged for manual valve positioning. Manual adjustment is carried out using an SW6 hex key, making commissioning and service work easier.

The two-piece housing is manufactured from self-extinguishing plastic, with a black lower section and red upper section. A plastic bracket and brass union nut are used for attachment to the valve. Electrical connection is provided by a fixed 3 × 0.75 mm² cable approximately 1.2 m long.

The protection rating is IP54 according to EN 60529. Permissible ambient temperature is -10 to +55 °C, permissible relative humidity is 5–95%, and the maximum temperature at the valve body is 100 °C.

The actuator may be installed vertically above the valve through to a horizontal position. Installation with the actuator suspended below the valve is not permitted. The actuator weighs approximately 0.7 kg.

Together with a HERZ 4037 3-way globe valve, HERZ 1771251 is suitable for automatic control of heating and cooling circuits, mixing assemblies, boiler systems, heat-pump systems and other HVAC installations requiring automatic mixing or diverting of the medium. The HERZ 4037 valve is ordered separately.

Technical information