Nest to Drayton wiser

30 Apr 2023
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United Kingdom
I am changing from a nest to a Drayton wiser.
As you can see from the image the wiring is live and neutral, it also has links from live to 2 and 2 to 5 CH is 3 and HW is 6 how would the wiring be on the Drayton wiser live and neutral would be the same but where would the CH and HW go 1,2,3,4 and would they need to be linked to the live.


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Assuming you have the two channel wiser:

L to L
N to N
Terminal 3 on the Nest is equivalent to terminal 4 on the Wiser
Terminal 6 on the Nest is equivalent to terminal 3 on the Wiser

There is no need for any additional bridging wires.

However, your current wiring is an example of pretty bad wiring practice!

Green and yellow wires used as switched lives is common in boiler electrics - not best practice, but not the worst.

However, in your case, additionally the heatlink is powering the Nest thermostat from terminals T1 and T2 - in this case, the MI state the heatlink should be earthed.
Also, the extra low voltage 12V supply to the thermostat, is sharing the same cable as a switched live for the hot water - if there was a fault with the cable, the thermostat could become live, and there isn't even the earth connection to mitigate the possibility!, it may be a good thing that you are moving to Wiser! :)

If you could rewire your new Wiser with a four core and earth flex, the installation could be a far more compliant and neater installation.
  • Thanks
Reactions: CBW
Thank you for the information all working had to change it from the nest as the nest was not working correctly as keep getting faulty heat link.
I agree with what you said about the wiring and will get 4 core cable and tidy it up.

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