Transmitters for heat flux monitoring

GS42H & GS44H (A/B/C/D/E)

General purpose bipolar range transmitters that are designed to be used with the HukseFlux HFP01 heat flux plate. The GS42H has two inputs and the GS44H has four inputs; all inputs have the same range. This range is hardware configured at the time of manufacture. The transmitter will have a suffix letter corresponding to the range - see the specification section for more details.




Hukseflux HFP01 heat flux sensor

HFP01 heat flux sensor is frequently specified for building performance monitoring studies, that is through walls and building envelopes. The total thermal resistance is kept small by using a ceramics-plastic composite body. The sensor is very robust and stable. It is suitable for long term use on one location as well as repeated installation when a measuring system is used at multiple locations.

HFP01 measures heat flux through the object in which it is incorporated or on which it is mounted, in W/m2. The sensor in HFP01 is a thermopile. This thermopile measures the temperature difference across the ceramics-plastic composite body of HFP01. A thermopile is a passive sensor; it does not require power. Using HFP01 is easy. The heat flux in W/m2 is calculated by dividing the HFP01 output, a small voltage, by the sensitivity. The sensitivity is provided with HFP01 on its calibration certificate. A typical measurement location is equipped with 2 or more sensors.




WBG Wall bracket docking kit

This kit enables fitment of the transmitter's built-in wall bracket to difficult or uneven surfaces. The kit provides additional docking security.

The following products are supported:

  • All GD, GC, GL and GS series transmitters
  • RP250GD repeater and RC250 receiver


Transmitter Specification

Range Type
(GS42H/GS44H suffix letter)
e.g. GS44HC
Range Accuracy
All 0.1% of range
A +/-5mV 10uV 2.5uV
B +/10mV 20uV 5uV
C +/-20mV 40uV 10uV
D +/-50mV 100uV 25uV
E +/-100mV 200uV 50uV

GS44H used with the Hukseflux HFP01 heat sensor:

(EU range can be used if required)

Location of installation Comment Comment Flux max
Voltage range
GS44H variant
Shaded No solar radiation Indoor 100 60 6 +/-10mV GS44HB
Shaded north wall Diffuse solar radiation Outdoor 300 60 18 +/-20mV GS44HC
Anywhere All solar Indoor/
1400 60 84 +/-100mV GS44HE

Eltek can also supply: GS44HA (±5mV range) and GS44HD (±50mV range) as above.

GS42H/GS44H GenII Transmitter Specification

RF specification: EN300-220
RF power: 10mW
Environment specification  
  Compliant to EN300-220: -10 to +55°C
  Actual: -30 to +65°C
  Humidity: 100% non condensing
Environmental rating: IP40
Dimensions (footprint): 78 x 41mm
Approximate height: 178mm (110mm without aerial)
Transmission interval range: 1 sec to 4 hours
Indicator (red LED): transmit active/on/off
Control switch (concealed): test mode / hibernate
Antenna socket: SMA


Common to all transmitters

Gen II Quick Start Instructions

Specific to this transmitter

GS42H/GS44H User Instructions