Defrost sensor MK2

Technical data: HBDF-MK2

HBDF-MK2 is a unique, but easy 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 of investment. 

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

Changes in the measured signal occur when ice is built up between the fins, as the sensor 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, both on new and old evaporators. The sensor can be installed in less than one hour, both on 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.

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
Voltage24 AC/DC + 10%
Max. possible resistance500 ohm
Plug connectionDIN 43650 - 4 pins
Analog output 4-20 mA
Environmental conditions
Ambient temperature-30...+50°C
Max. pressure100 bar
Protection degreeIP65
VibrationsIEC 68-2-6 (4g)
Mechanical specifications
Thread connections3/4” NPT & 1" BSP
Material - liquid partsAISI 304 / PTFE
Material - electronic partsCoated aluminium
House typeFront
EMC testEN 61000-2
LED indicationRed LED
ConfigurationPush bottom

Ordering code

Wire lengthOrdering code
10 mHBDF-MK2-10
20 mHBDF-MK2-20
30 mHBDF-MK2-30
HBDF-snapON ClipsOrdering Code
25 pcs. of 8-10 mmHBDF-SnapONClip8-25
50 pcs. of 8-10 mmHBDF-SnapONClip8-50
25 pcs. of 10-12 mmHBDF-SnapONClip10-25
50 pcs. of 10-12 mmHBDF-SnapONClip10-50
25 pcs. of 12-14 mmHBDF-SnapONClip12-25
50 pcs. of 12-14 mmHBDF-SnapONClip12-50
25 pcs. of 14-16 mmHBDF-SnapONClip14-25
50 pcs. of 14-16 mmHBDF-SnapONClip14-50
25 pcs. of 16-18 mmHBDF-SnapONClip16-25
50 pcs. of 16-18 mmHBDF-SnapONClip16-50
25 pcs. of 19-22 mmHBDF-SnapONClip19-25
50 pcs. of 19-22 mmHBDF-SnapONClip19-50
25 pcs. of 22-25 mmHBDF-SnapONClip22-25
50 pcs. of 22-25 mmHBDF-SnapONClip22-50
USB programming cableHBxC-USB