Replacing SUNVIC TLX 2259 with Center RF Programmable Room Thermostat & Relay Box

[FitzCh]

Hi!

I would like to replace my old thermostat Sunvic TLX 2259 with the following wiring

With a Control RF Programmable Room Thermostat & Relay Box

What is the correct way to wire the thermostat? It will work as a simple thermostat, no combi boiler, no zones.

According to the diagrams and my understanding it should be:

SWITCHED LIVE - YELLOW (TERMINAL 1 on OLD) to TERMINAL B (on NEW)
RED (TERMINAL 3 on OLD) to the second (from the left) TERMINAL L (on NEW)
BLUE (TERMINAL 4 on OLD) to the first terminal N
Third (from the left) TERMINAL L wired to TERMINAL A (on NEW)

Any advice is appreciated!

 

[stem]

You have identified the existing thermostat wires correctly, with the possible exception of terminal (3). The Satchwell Sunvic thermostat you have now does not have time control, so there would normally be a programmer somewhere to provide on/off control. If so, terminal (3) is not actually a 'permanent live', it is a 'switched live' fed from the programmer.

Here are some suggestions:

1. Wire in the programmable thermostat receiver as you suggest and leave any existing programmer set to have the central heating 'on' permanently. The new programmable thermostat will then control both time and temperature functions. [This will work OK, but is a bit of a fudge & not how a professional would do it]

2. Install a wired digital thermostat without a receiver that is battery powered in place of the Sunvic, instead of a programmable thermostat, and continue to use the existing programmer for the time control.

3. Remove the Sunvic and associated wiring, wire in the 'relay box' to the central heating wires presently going to the programmer, and if you have timed hot water, install a single channel timeswitch for that in place of the dual channel programmer.

 

[FitzCh]

Thanks for your response and suggestions!

Yes, there is an old type SUNVIC programmer with a timer function, and it is set to CONSTANT (always ON), so the terminal 3 is in this case a permanent live.