It is hard to judge the skills of others, and as an industrial spark I had very little to do with domestic central heating control. @Taylortwocities has pointed out the remote sensor, I have some thing similar, I used Nest Gen 3 because where the boiler is and so the controls, is remote from the main house, and I only have 2 wires to control both DHW and CH, and Nest Gen 3 allowed me to have control in the main house, even when boiler was in the flat.

However I was under the impression that Nest worked with Energenie TRV heads, but that I found was wrong, so I have spent out around £250 on a wall thermostat which does not do as I want.

When I employed a heating and ventilation engineer I was surprised to hear him admit he did not have a clue how to wire my system. But the electrics did not worry me, it was the servicing of the boiler and plumbing I wanted him for.

Everyone tends to look at what they have, and have blinkers to other systems, I see people asking how many motorised valve have you got, the answer being two times two port valves, they say you have a S Plan, however I have two times two port valves and it is a C Plan.

It is so easy with a forum to make errors, I did with your system, noted the extra terminals, but thought likely it was so it could be volt free, not a sensor.

I really don't know why we still have wall thermostats, I would have thought today we would just have a hub that collected information from the TRV's, the Honeywell EvoHome it seems does do that
but most seem to still have temperature sensing in the wall mounted device even if it also connects to TRV heads. In the main it is down to cost, at £50 per TRV head automation becomes expensive, their are electronic heads cheaper, I got 5 x eQ-3 heads at £15 each with bluetooth back in 2019, but without linking to main wall thermostat, in mother house I managed without linking, just had the TRV set below the wall thermostat and after tweaking the lock shield valves it worked well.

This house the hall cools too slow, I can adjust heating with the lock shield and the TRV, but I can't adjust cooling.
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Only a DIYer but this had me intrigued.
Thoughts only. I am not a pro,

The temperature as well as time is set on the TP9000
It uses the remote TS2 (connected to 5 & 6) to measure the temp

Ignore the sensor wires (make safe)
Replace the programmer with something like a Wiser hub.
The Wiser wall/radiator thermostats then control the boiler activation.

Couple of links that helped with my understanding.

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Just had a thought actually, a Nest learning thermostat would work if you swapped out the wall mounted remote sensor for the thermostat and utilise the wiring. Obviously this would still need a wiring swap, but could be done by OP?
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on the contrary. As I have tried to point out, many of the standard 2-channel controllers do NOT provide the ability to connect the additional sensor. At least not out of the box.
Probably it would need connecting to the wiring centre, not to the controller as you have with the TP9000.
My advice: Find an electrician who enjoys heating controls and let him/her select the product that will do the job. Otherwise you’ll buy the wrong thing and waste your money.

EDIT. why don’t you just buy a new TP9000 and pop it on the existing backplate? Problem solved!

Make sure you get the correct model/version. I bet there’s more than one.
I contacted a well-qualified electrician and he advised upgrading to a Hive Thermostat/Controller. He has seen the picture of the existing backplate and wiring.

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