LightwaveRF Comfy LW920 Professional Series Instruction Manual page 19

Install 2: Y plan
Access the wiring centre
The Boiler Switch needs to be wired in place of the existing room thermostat.
In order to locate this connection, you must gain access to the system wiring
centre. This is often located near to the hot water cylinder. Make sure that
you turn o the mains power. The connections in the wiring centre for a Y
plan setup are usually to a standard format. A typical example (Honeywell
system) is shown in the diagram on the next page.
Locate the room thermostat terminals
Once you have accessed the wiring centre, you need to locate the room
thermostat's connecting wires, and terminals that they are connected to.
There should be two main switching wires (usually white and black). In some
cases there will also be a neutral connection (usually blue). Make a note of
the locations before disconnecting the wires, as they may not be marked.
Locate mains power terminals
The Boiler Switch also needs to take mains power. This can be routed from
live, neutral and earth terminals located in the wiring centre (see the
example in the diagram). The terminals are usually located next to or near to
the room thermostat connections. Take extreme care when dealing with live
mains; if unsure always consult an electrician as an incorrect install could
result in damage being caused.