JohnnyP said:
Firstly I have absolutely no electrical experience so when I initally looked up the manufacturer's website (product given with no instuctions) the wiring diagrams looked like chinese to me.
But you didn't say that. You said "Trying to wire in a Honeywell T6360 thermostat. I have a 3 core mains cable (red yellow blue) and 4 connectors (nubered 1 to 4) in thermostat. " - no indication whatsoever that you had a wiring diagram from the website that you couldn't understand, and every indication that you hadn't looked on the website at all.
Why do I say that?
Because this is what is on the website:
and it is (or ought to be) trivially simple to understand. It is not "chinese". It shows
exactly what you describe below:
Live - Terminal 1
Neutral - Terminal 2
Switch-Live - Terminal 3
And that info was what Spark123 pointed you at, to which you said "thanks a lot", not "I've looked at that and I can't understand it".
So all in all the reasonable assumption was that you had
not looked for the wiring diagram on the Honeywell website before posting here.
All I wanted was any help connecting three wires as I'm not prepared to pay an electrician £70, thanks.
God forbid I should turn to a public DIY forum for help!
And god forbid you should consider paying someone to do something that is beyond you?
How completed unreasonable of me.
If you'd explained that you'd got a wiring diagram that you couldn't understand, and put it in your message for people to interpret for you, and not given the impression that the Honeywell website document was new to you, then you would not have made yourself look like someone who hadn't done the most basic research themselves before coming here.