Frost alarm


Electronic freeze protection alarm with warming function, double relays and digital display. 24V AC.

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Description CFA-24V

CFA is an electronic freeze protection alarm with a digital display that is used to monitor frost in air heating systems that use water as the heat carrier.

CFA is connected to a temperature sensor that measures the water temperature in the heating coil. The water temperature in the heating coil is normally regulated by another regulator/DUC with the control signal (0-10 or 10-0V) connected via CFA to the
control valve. If the water temperature in the coil drops without any response from the regulator / DUC, CFA starts regulating the control valve.

When the water temperature in the coil drops below the pre-set alarm temperature, both relay outlets fall (normally activated).

CFA can be connected to a range of temperature sensors: Pt100, Pt1000, Ni1000 plus Calectros NTC and PTC sensors in the ETF series. Pt1000 is a factory set sensor.

The temperature measurement in CFA can be adjusted if necessary. Range: -3°C to +3°C in steps of 0.1°C.

CFA monitors the temperature sensor so that a short circuit or interruption on the sensor circuit triggers the alarm and sets the control signal at 100%.


CFA is mounted on a DIN rail and is suited to Norm enclosures.

For more information see the installation manual that comes with the product.


  • Very easy configuration
  • Backwards compatible with Calectro’s freeze protection
    alarm EFST-6
  • 2 alternating potential-free relays
  • Illuminated digital display
  • Fine-adjustment of the temperature measurement
  • Selectable output signal 0-10V or 10-0V

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