Replacing Danfoss FP975 with nest

5 Nov 2016
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United Kingdom
Hi all,

I'm looking for guidance on wiring a nest 3rd gen to replace my existing set up. The current set up is below:

Boiler: Worcester Greenstar 18Ri
Programmer: Danfoss FP975
Wired Thermostat: Danfoss RMT 230

The current programmer connections are as follows along with my understanding of how they should connect to nest

Earth - not used - does the heat link need earth?
Neutral - to heatlink neutral
Live - to heatlink live
1 - HW on - link to heatlink 6
2 - jumper wire to live - link to heatlink live
3 - HW off - link to heatlink 4
4 - HW on - link to heatlink 3
5 - jumper wire to live - link to heatlink live
6 - not used

Can someone confirm this part is correct or correct me if wrong?

I understand I then need to take a feed from T1 & T2 to the thermostat which will give me the 12v feed for the nest thermostat. My current stat has wired connections as per below but they aren't labelled and no other labelling in the wall box behind the programer. I have shown in brackets what I believe the wires are and I understand I can repurpose 2 of these for the thermostat and tape the other up but how do I identify these in the wall box as they aren't connected to the programmer?

4 - blue (neutral)
5 - unused
1 - red (live)
3 - unused
2 - yellow (sw/l)
Last edited:
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Did you ever get anywhere with this? Thinking about installing Nest myself and have a Danfoss FP975 so looking some advice

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