Replace British Gas UP2 Programmer with Nest 3rd Gen

Thanks for all the abuse, now go eat **** (y)
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I think this is what the OP was after... and since google brought me to this thread, we may still help others:
This is my wall plate, it looks to be hooked up identically - with a slight difference in wire colours. The numbering is the same and it was connected to a UP2.
This is the nest wiring. Note that you can connect the live wire across more than one terminal. Yes, the wiring diagrams in the manual are straightforward if you are familiar with that type. If you are doing DIY - it might not be too obvious that you don't have to have independent wires for every connection. The Y-plan diagram is the correct one.

For my wiring:
  • Light Blue - Neutral - Nest N
  • Brown - Live - Nest L, 2, 5
  • Red - Central Heating N/O - Nest 3
  • Yellow - Hot Water N/C - Nest 4
  • Dark Blue - Hot Water N/O - Nest 6 (Common on Water Tank)
Your Hot Water needs two wires. One to switch on when you tell it, the other to switch off when it is hot enough.

Your Central Heating works by connecting "Call for heat" to the Live wire. Beware - if you're removing an existing thermostat, you'll be putting a break in that connection unless you deal with it. My advice is to keep the thermostat in place for now and find a guide for that (I'll post one for an RS1 when I get round to removing it).

Another beware... your thermostat probably uses mains AC - not what your Nest controller needs (or can cope with). I also advise against putting an AC/DC Converter in the wall as they can get a tad warm.
Excuse reviving an old thread but I'd rather that then post a new thread with the same issue.

I have a up2 programmer but don't want the heatlink in the same place as shown above, it's no where near the boiler. I can remove remove the wires from the up2 but wonder how to wire the heatlink at the boiler.

These are the wires at the boiler currently in place. It's a Worcester greenstar that does the heating, separate hot water tank.
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Actually ignore me, the airing cupboard is behind the up2. I'll feed the wires back into the cupboard and have the heatlink in the airing cupboard and thermostat over the hole left behind.
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