Hi Malcolm, what make and model of combi boiler do you have?
The vast majority of combi boilers have a small terminal block with two wires from the boiler PCB which go to them, you remove the jumper bridging the terminals within the block, then take them to your timer or thermostat.
You then need to run another pair of wires from 230V mains, to power the thermostat, the mains cables go in the L and N terminals within the back plate of the timer, and the two wires you extended from the terminal block under the boiler go the switch normally marked common and switch or terminal 1 and 2.
Please let me know if you have any follow up questions.
I havent heard back from you in a while, do you still require assistance?
Good morning Malcolm, I havent heard from you in the last couple of days do you still require assistance?