Techem FHKV data II

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The device as seen from the front, this side contains a small LCD screen.

The FHKV data II is a heat metering device often attached to individual radiators.


The FHKV data II (2) is an inexpensive heat meter made by Techem. It can be found for around 10€ on various internet pages. External features show a small LCD screen with space for five 7-segment numbers, as well as two icons. One of the icons is a pen, the other an antenna dish. The display is slightly inset into the device. Above the right of the display is what seems to be an optical communications port. The device supports remote access to the meter. The bottom contains various information about the device, such as approvals and alike. It also contains a table with temperatures:

Type Temperature Additonal field
tmin 35 °C (95 °F) 2F
tmin 55 °C (131 °F) 1F
tmax 110 °C (230 °F)
tmax 130 °C (266 °F) FF


  • Size (approximate, LxWxH):
    • 22 mm x 40 mm x 116 mm

Remote capebilities (RF)

The device supports a protocol known as "Wireless-M-Bus", which is an open standard. This means it can be easily received by open-source tools, such as wmbusmeter.


The Techem FHKV Data III PCB

The FHKV Data 3 seems to be build around a chip with the markings "9CCS4HT G4 M430U 300 RELEASE 4". The internet did not return any data on that IC. The PCB has to measure at least two temperatures (one on the inside and another "room" temperature). It also seems to have some kind of (inactive?) tampering detecion. Even though the back was removed, no visual error code was given.