Replacing the thermostat for a combi boiler system (honeywell to Drayton Wiser)

Hello everyone. I am hoping for some help with changing my thermostat. I have never done this before. My current setup is a Honeywell wireless thermostat that is >10 years old and dying. I want to replace it with a Drayton Wiser single channel kit. Pic 1 is the current wiring for the Honeywell. I’m guessing one neutral, two lives, two boiler switch wires, and earth just touching the case?

Second pic is what I am going to. Am I right in thinking that neutral goes to N, the two lives go together into L, the boiler switch wires go into A into 3 and B into 1, and the earth goes bottom right?

whatsnottolike said:

Am I right in thinking that neutral goes to N, the two lives go together into L, the boiler switch wires go into A into 3 and B into 1, and the earth goes bottom right?

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Yes, that should work

You may find that the brown wire in L is connected directly to A - I only see a 3 core and earth (blue, yellow & red) cable behind the existing stat.

Ensure the power to the boiler and thermostat is completely isolated, before disconnecting!

Thanks so much! Yes, I have switched off the power to the whole house. Better safe than sorry.

This is what I have now. Does this look okay? The brown wire is just a loose wire connecting L to A in the old fitting. L to 1 in the new fitting. I checked the diagram again and realised that the power needs to go into terminal 1.

All the wires could do with shortening. I’d have to go and buy a tool for that though. I will do if that’s what is needed of course.

whatsnottolike said:

Does this look okay?

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Yup, that will do!

Coming back to report that this seems to have gone well. The house is still standing, no-one has died, and the new Drayton Wiser system is connected and working fine Thanks for the help!