Room stat replace

[oldiediyer]

I have an old Satchwell TLX2356 room stat wired with a Honeywell k42008628 frost kit.
The wires in the room stat are
Yellow to terminal 1
Red to terminal 3
Blue to terminal 4

Both the Yellow and Red wires are constant live

I want to replace with a Honeywell DT90E stat , can you advise me on the correct wiring please.

 

[ericmark]

3 = feed in
1 = feed out
4 = neutral
However it will work without a neutral so needs testing, Google TLX 2356 wiring diagram came up with the results, if you need some one to do that for you, I think time to give up.

I am sure the DT90E came with a wiring diagram.

 

[Taylortwocities]

Both the Yellow and Red wires are constant live

I doubt that. How are you testing for “live”?

 

[RandomGrinch]

As the DT90e is battery operated, the blue wire (probably neutral), currently in terminal 4, won't be required.
Safely isolate this in a separate terminal block, or Wago.
The red and yellow wires can then connect into terminals A and B.