Defrost on Demand Sensor MK2

Technical data: HBDF-MK2

HBDF-MK2 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 that it can easily save up to 40% of energy and thereby fast return your investment. 

The sensor measures the thickness of ice built up between the fins and emits a 4-20mA or digital ON/OFF signal to the control systems. A temperature sensor (PT1000) is located at the fins, near the bottom part of the evaporator.
It senses when defrost is completed and stops the sequence.
The defrost sensors are based on the capacitive measuring principle, in which an insulated steel wire acts as one conductor and the evaporator fins and tubes act as the second conductor.
Together the make up a viable electrical capacitor.

Changes in the measured signal occur when ice is built up between the fins, as the sensor measures the dielectric difference between the air and ice.

The sensor can be installed in less than one 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 PA12 or PTFE - coated wire, which is mountedbetween the fins of the evaporator in theair inlet side with special HB Snap-On clips or standard nylon cable ties.The HBDF-MK2 sensor is available in 3 versions,  with a 10-, 20-, and 30 meter wire and as standard, Low Temperature (LT) or Heat Pump-version (RS).

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 web-site.


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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



Defrost sensor 19mA blå02 web




Power supply
Supply voltage24 AC/DC
Electrical connectionScrew terminals
Electrical consumption600 mA
Max. load500 ohm
Analog output 4-20 mA
Relay output 2 x 5A, NO/NC
Relay output 24V 2 x 3A, NO/NC
Environmental conditions
Ambient temperature-30...+50°C
Protection classIP65
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
LED indicationGreen and red
ConfigurationPush button

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-RS
Defrost sensor for heat pump applications20 mHBDF-MK2-20-RS
Defrost sensor for heat pump applications30 mHBDF-MK2-30-RS
Electronic Part for HBDF-MK2Spare part must be calibratedHBDF-MK2-EL
HBDF-snapON ClipsPiping in mmOrdering Code
Bag of 25 pcs.8-10 mmHBDF-SnapONClip8-25
Bag of 50 pcs.8-10 mmHBDF-SnapONClip8-50
Bag of 25 pcs.10-12 mmHBDF-SnapONClip10-25
Bag of 50 pcs.10-12 mmHBDF-SnapONClip10-50
Bag of 25 pcs.12-14 mmHBDF-SnapONClip12-25
Bag of 50 pcs.12-14 mmHBDF-SnapONClip12-50
Bag of 25 pcs.14-16 mmHBDF-SnapONClip14-25
Bag of 50 pcs.14-16 mmHBDF-SnapONClip14-50
Bag of 25 pcs.16-18 mmHBDF-SnapONClip16-25
Bag of 50 pcs.16-18 mmHBDF-SnapONClip16-50
Bag of 25 pcs.19-22 mmHBDF-SnapONClip19-25
Bag of 50 pcs.19-22 mmHBDF-SnapONClip19-50
Bag of 25 pcs.22-25 mmHBDF-SnapONClip22-25
Bag of 50 pcs.22-25 mmHBDF-SnapONClip22-50
USB programming cableAccessoriesHBxC-USB


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