LightwaveRF Comfy LW920 Professional Series Instruction Manual page 14

Install 1: combi boiler
Locate the room thermostat (RT) terminal
Once you have accessed the wiring centre, you need to locate the room
thermostat terminals. You will need to refer to the main 'PCB' wiring diagram
in your boiler manual.
The connections should usually be marked as 'room thermostat', 'RT', or, in
some cases, 'temperature sensor' or 'TS'. Be aware, however, that the
terminology in some boiler manuals may vary. There may be a 'jumper'
(small loop of cable) connecting the two terminals, as in the diagrams below.
This needs to be carefully removed. If this terminal already has an existing
thermostat connected to it, then this should be disconnected.
Example Alpha and Vaillant Boiler wiring diagrams with correct terminals circled.