Help to Understand wiring diagram for ACL Lifestyle Wiring Centre LWC1

Hi All,

I have been a reader of the firum and most times I have found the answers to any questions that I have had, so thanks to all the members who post some brilliant stuff here.

I have a generic question. I am trying to understand how th heating system at my home works so I gathered information by looking at whats installed. I think I have now fair enough idea whats installed. When I look at the wiring diagram (see attached RTS1) for the room thermostat it shows 3 L and N. Can any one please tell me what 3 stands for and similarly on the cylinder thermostat HTS3 what do number 1 and 2 mean. Is this a standard notation that I can find somewhere. Thanks you.

No standard letters / numbers for connections,

The numbers are selected by the manufacturers and are often product specific. However they do provide information describing their functionality.

RTS Room Thermostat.


Terminal 3 is the switched live. So when heat is required, the switch operates, thus linking terminals L and 3, so 3 becomes live and the heating comes on.


HTS3 Cylinder Thermostat


Same principle here. The 'Common' terminal is 'L, and terminal '1' is call for heat. The switch is between these two terminals.

Where systems have a 3-Port valve like yours, there is also a connection required to the 'Satisfied' terminal. This tells the motorised valve (via its grey wire) that the hot water is 'Satisfied' (i.e. not required) and closes the hot water outlet.

The genetic diagram for Y Plan does not show a permanent line to the boiler, and a supply from the boiler to run the pump, but other wise it is the same. Y Plan is not easy to understand because the three port valve is a weird unit John Ward does a good you tube on how it works.