Replacing Honeywell CM927 with Nest-E

13 Sep 2020
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United Kingdom
So, we got a free Nest E from our electricity supplier, and want to install it to replace or wireless Honeywell thermostat.

I’ve found other posts that say that for the ‘posh’ Nest , wire A on the Honeywell goes into 2 on the Nest Heat Link and that wire B goes into 3, with the L and N going into corresponding L and N on the Nest heat link.
The trouble is, the heat link for the Nest-E doesn’t have a L, N, 2 or 3!!
The options we have are C, NO, FP, OT1 and OT2.

All help gratefully received, thank you.


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Switch the power off first - some of those wires are at 230V even when the heating isn't on.

Red and yellow connect to C and NO. The other terminals are not used.

The blue and black wires are not required, but MUST be put into their own separate insulated connectors.
Thanks Flameport, but surely that’s way too easy? I thought, looking at the diagrams that might be the case, but assumed I was missing something! Thanks again.

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