Drayton system | Removing/Bridging old wall thermostat

[Jxta]

Hi Folks,

Been through previous threads but everyone's setup seems to be a little different, and I can't work it out based on those.

Recently removed an old Drayton programmer, and replaced it with one of their Wiser 2 channel models - https://cdn.shopify.com/s/files/1/0...Drayton_6490238_T_compressed.pdf?v=1757346664

For the moment, I have the old wall thermostat turned up to max to keep a closed circuit, and everything works fine; but soon we are decorating the hall and need the old thermo gone.

Based on what I've read and what I can see in the house, I believe I have an S plan system and the wall thermostat may be wired to the programmer rather than the wiring centre? (this is the part I'm unsure of). Pics below.


Programmer:

Wall thermo:

Wiring centre:

On the programmer, I think the blue wire from N needs to be disconnected and one of the reds from L needs to be disconnected too (but which one!), and thereafter bridge at the programmer, or preferably at the wiring centre if possible.

I'm quite comfortable with electrics and have a multimeter to hand, just need a point in the right direction.

Side question - I was hoping the hot water cylinder would have its own thermostat, as the hot water here would scald you, but I can't see one? Is it unusual for an S plan setup to not have one?

Cheers,
Gordy

 

[CountryFan]

Looking at the wiring diagram I'd say number 7 yellow is the room stat when switch live is made, cylinder stat I think is behind the black box which appears to be connected to number 5. Obviously not wired as per the sticker on the back of the wiring center.

 

[Jxta]

Looking at the wiring diagram I'd say number 7 yellow is the room stat when switch live is made, cylinder stat I think is behind the black box which appears to be connected to number 5. Obviously not wired as per the sticker on the back of the wiring center.

Yeah its evident the wiring diagram for the centre hasn't been followed and doesn't help me much.

How am I best going about confirming 7 is indeed the yellow from the room stat - just do a continuity test with a multimeter if the leads will stretch far enough (or extend them with other wire) ?

If position 7 does check out, is it feasible to make the bridge in the wiring centre? What does the extra red wire and blue wire in the programmer plate tell me?

Found the cyl stat and adjusted it - thanks!

 

[CountryFan]

How am I best going about confirming 7 is indeed the yellow from the room stat - just do a continuity test with a multimeter if the leads will stretch far enough (or extend them with other wire) ?

You could do a live test. Set hot water to off, heating on and thermostat calling for heat. Test Earth to 7 on Volts AC - should get 240vac. Turn thermostat down and you shouldn't get much if any voltage.

If position 7 does check out, is it feasible to make the bridge in the wiring centre?

Yes

What does the extra red wire and blue wire in the programmer plate tell me?

It could be the Live and neutral feed to the room thermostat. You could remove them at the programmer and test for voltage at the thermostat?

 

[Johnmdc]

I would say that the yellow in 7 and the red in 6 are the wires going to the thermostat.
Disconnect both of these and the blue wire that is in the same cable as them to totally disconnect the room stat.
Then move the yellow wire that is currently in 6 to 7 for the heating to work.

 

[Jxta]

Bingo!

Your tests checked out @CountryFan

Wired as you suggested @Johnmdc and everything is working perfectly.

Old thermostat and wiring pulled out of the wall and in the bin.

Thanks again for the help.