Thermostat Replacement Wiring

[SW1987]

Hi All,

I'm replacing my old analogue thermostat (Sunvic TLX 2259), which currently has 4 wires, a brown, black, light blue and green yellow.

Im replacing it with a Salus RT300 digital programmable room thermostat, which has 3 connections; Live, Switch Live and Earth.

The controller is connected to an existing Baxi boiler with a manual timer override on the front.

How do I know which wires connect in, and how do I get this to operate my boiler?

Thanks,

Simon

 

[stem]

First of all the Salus RT300 is not a programmable thermostat. It is just a thermostat, so you will still need to use the timer on the boiler as you do now.

The Sunvic should have a circuit diagram in the lid. From that you can identify the wires as being:

Terminal 3 = Live
Terminal 1 = Switched Live (or heating on)
Terminal 4 = Neutral
Earth = Earth

Unfortunately which colour is which would have been chosen by the original installer, so I can't say what each colour is, but:

The wire presently in the Terminal 3 goes to Salus L.

The wire presently in Terminal 1 goes to Salus SL

The wire presently in terminal 4 (neutral) is not required because the Salus is battery powered. So insulate it in a screw connector and tuck it safely out of the way.

Earth = Earth