The ST-21 controller with an LED display is designed to control the central heating water circulation pump. The controller's mission is to activate the pump when the temperature reaches the set value and deactivate it if the boiler cools down below the set value from the specified hysteresis value.

This mode of operation prevents unnecessary pump operation, saving electricity and extending the pump's lifespan.

The ST-21 controller can also operate as a thermostat, shutting off the pump once the set temperature is reached. It features an ANTISTOP function, which prevents the pump from stopping out of season, as well as an antifreeze function that permanently activates the pump if the temperature drops below 6°C.

• Central heating or hot water pump control
• Ability to operate as a thermostat
• Anti-stop function
• Antifreeze function

Technical Specifications:

• Power supply: 230V/50Hz +/-10%
• Maximum controller power consumption: 2 W
• Ambient temperature: 5÷50°C
• Maximum pump output load: 1 A
• Central heating temperature adjustment range: -25÷85°C
• Hysteresis: 1÷10°C
• Measurement accuracy: 1°C
• Sensor temperature resistance: -25÷90°C
• Fuse insert: 1.6 A
• Sensor cable length: 1.5 m

Manufacturer code: WG.14.0110