Techical data: HBDF

HBDF-MK2 is a simple solution for energy-optimal automatic
defrosting of evaporators. It results in energy saving, gain more
freezing capacity with optimal defrost periods. The sensor measures
the thickness of ice building up between the fins and sends
a 4..20mA or digital ON/OFF signal to the control systems.

The Defrost sensors are based on capacitive measuring principles,
in which an isolated steel wire acts as a conductor and the
evaporator fins and tubes act as the second conductor jointly
forming viable electrical capacitor. Change of the measured signal
occurs when ice is build-up between the fins as the sensor is
measuring the dielectric difference between air and ice.

The sensor can be installed in less than one hour, on both new
and old evaporators. It can be installed when the system is in
operation, and therefore, a system shutdown is not necessary.
The electronic part is mounted on the evaporator’s frame using
2 screws. The mechanical part consists of a thin PA12 or PTFE-
coated wire, which is mounted between the fins of the evaporator
in the air inlet side with special HB Snap-On plastic clips or
standard Nylon strips. HBDF-MK2 is available in 3 variants, with
a 10m, 20m, and 30m wire respectively.

After installation, the sensor should be calibrated/configured to
the evaporator it is mounted on. This is done using the HB-TOOL
(PC-based software tool), which can be downloaded via this
HBDF-MK2 is a simple solution for energy-optimal automatic
defrosting of evaporators. It results in energy savings of approximately
10%, thus quickly recouping its cost.

The sensor with build in control relays will start the defrosting
based on the ice thickness and stop the defrost when the ice is
melted and the temperature outside the evaporator tubes rises
above 5 C/41 F to 10 C/50 F (adjustable).

Product features

One box start and stop the defrost

Stop the defrost when ice is melted (rising temperature on the evaporator tubes).

Save energy = money on defrost.

Gain more capacity.

Save energy = save money and reduce the CO2 emission.





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
Refrigerant temperature-60...+80°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


Wire ProbeOrdering code
0 mHBDF-MK2-10M
20 mHBDF-MK2-20M
30 mHBDF-MK2-30M
HBDF-snapON ClipsOrderinge Code
8-10 mmHBDF-snapONClips8
10-12 mmHBDF-snapONClips10
12-14 mmHBDF-snapONClips12
14-16 mmHBDF-snapONClips14
22-25 mmHBDF-snapONClips22