Which wires where??

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I've got an old potterton thermostat which is wired in already like the pic attached. I've bought the Honeywell home thermostat to replace it. My question is which wires and where do they go in my new thermostat? Many thanks
 
Its not letting me post the pics for some stupid, ill be back once ive figured it out. Thanks
 
Hopefully attached
 

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In then main, the thermostat cover will have some sort of wiring diagram. For example
1768139174994.png
this may not mean much to you, but most on here can work out from that diagram what terminals do what.

Help us help you.
 
You don't give the model of the old thermostat, but it looks like it is a Potterton PRT100. If so, the connections would be:

Pic 3.jpg


If your thermostat has the same connections as above shown inside its lid, then the connections are:

(3) N= Neutral (Blue Wire)
(2) H = Heating on (Yellow Wire)
(1) TL = Thermostat Live (Red Wire)

Again you don't state the model of the Honeywell Home, so if yours is the same as below as per @CountryFan the connections are:

Screenshot 2026-01-12 153122.jpg



C= Terminal not used
B = Heating On (Yellow Wire)
A = Thermostat Live (Red Wire)

This thermostat does not require a neutral connection. To avoid damage do not connect the neutral to the thermostat. It should be insulated / isolated and placed out of the way.
 

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