Fibaro universal sensor and relay for UFH

I was thinking of using the Fibaro universal sensor and relay to monitor and control my electric underfloor heating, the universal sensor would be connected to a DS18B20 Digital Thermometer to measure floor temp, I would also use a wall thermostat to measure air temp, the relay would be used to switch the UFH on and off.

The UFH and relay are connected using using mains power through a fused switch, how would I power the universal sensor?

It takes a wide range of DC voltages so any wall wart power supply you’ve got that’s not being used should be fine.

Will it not take power from the mains or the relay?

if you read the manual there you can find the input and output voltages…
like tim says use a simple DC power supply
input is 9-30v DC
output can have max 36V DC / 24V AC
you can connect the powersupply to the mains

The problem I have is that my current setup doesn’t have plug sockets near the fused spur that powers the UFH, I don’t really want to add sockets and have a DC PSU on display.

??? ???

well then take the plug of the adapter and attach the mains input of that to the relais 220v input ?