Defrost Sensor & Controller

Technical data: HBDF

HBDF is a unique, but easily adaptable solution for automatic defrosting of evaporators. Optimal defrosting results in energy savings and increased freezing capacity. Experiences from existing installations have shown savings up to 40% of energy and thereby fast return on your investment.

The sensor can be used on evaporators with minimum 5 mm fin spacing in cold rooms. The sensor works on heat pumps, but it requires special conditions and larger fin spacing. Contact us for more information.

The defrost sensor is based on the capacitive measuring principle, in which an insulated steel wire acts as one conductor and the evaporator fins act as the second conductor. The sensor measures the ice thickness between the fins. The output is either a 4-20mA analog output or a more advanced digital output to the control system. The digital output can be used directly to control the defrosting and includes a temperature sensor which senses when defrost is completed.

The sensor can be installed in less than an hour, on both new and old evaporators. It can even be installed when the system is in operation, hence shutdown is not necessary. The electronic part is mounted on the evaporator’s frame by using 2-4 screws. The mechanical part consists of a thin coated wire, which is mounted between the fins of the evaporator where ice built up. The wire is either mounted using standard nylon cable ties or put around the pipes. The HBDF sensor is available in 3 versions, with a 10-, 20-, and 30 meter wire and as Standard, Low Temperature (LT) or Heat Pump-version (OD).

After the installation, the sensor should be calibrated/configured to the evaporator by using the HB-TOOL (PC-based software tool), which can be downloaded from our website.


Shop image

Product features

Defrost starts only when needed (on demand)

Stop the defrost when ice is melted (input from temperature sensor located on evaporator surface)

Save energy compared with timer based defrosting

Gain more capacity - fewer and shorter defrost cycles

Easy installation - also on existing sites


 HBDFmk2 Electrical Connection00


Power supply
Voltage24 AC/DC
Current consuption - sensor only*600 mA
Electrical connectionScrew terminals
Sensor design3-wire
Analog output4-20 mA
Max. load500 ohm
Relay output2x5A, NO/NC
Relay output 24V 2 x 3A, NO/NC
Cable entry PG9 / M12
Environmental conditions
Ambient temperature-30...+50°C
Protection degreeIP65
VibrationsIEC 68-2-6 (4g)
Mechanical specifications
Material - mechanical partsAISI 304
Material - electronic partsNylon 6 (PA)
Certifications - EMC EmissionEN 61000-3-2
Certifications - EMC ImmunityEN 61000-4-2
Type of configurationHB Tool
Tool to be usedHB software
USB Programming cableHBxC-USB
* Total consumption is sensor consumption plus output and it depends on ambient temperature.

Ordering code

DescriptionWire lengthOrdering code
Defrost sensor MK210 mHBDF-MK2-10
Defrost sensor MK220 mHBDF-MK2-20
Defrost sensor MK230 mHBDF-MK2-30
Defrost sensor MK2 for low temperature10 mHBDF-MK2-10-LT
Defrost sensor MK2 for low temperature20 mHBDF-MK2-20-LT
Defrost sensor MK2 for low temperature30 mHBDF-MK2-30-LT
Defrost sensor for heat pump applications10 mHBDF-MK2-10-OD
Defrost sensor for heat pump applications20 mHBDF-MK2-20-OD
Defrost sensor for heat pump applications30 mHBDF-MK2-30-OD
Electronic Part for HBDF-MK2Spare part must be calibratedHBDF-MK2-EL
USB programming cableAccessoriesHBxC-USB