MKC MK722 Mode D'emploi page 27

c. Wiring the Receiver as wiring diagram below.
A Pre-Installed Wire installed between wire terminal "COM" and "L". If Aplliance and
Thermostat power sources are the same. User only need to connect Live wire to "COM"
terminal.
If the Appliance and Thermostat power sources are NOT the same. User need to remove
this wire first. And then install the Aplliance Live wire to "COM" terminal and Thermostat
Live wire to "L" terminal.