Give us a clue.
Boilers come both with all stuff built in and as a plain heating unit with all the controls outside of the boiler. Looked on line for your model but nothing to show what type it is.
I would guess the second type and as far as the boiler goes again two types.
One which is just switched off and on, and
One where a cool down time is required and so has both live supply and a control wire.
With the latter the control can need to be controlled by a volt free device (likely 24v control circuit) or where it used 230v for control so volt free contacts are not a requirement.
OK that's what we need to know about the boiler. Assuming it is controlled by an array of devices outside the boiler the next we need to know is what plan it is following. Honeywell one of the major manufactures produced plans called W, S, Y etc.
These plans allow one to have thermosyphon or pumped domestic and where motorised valves are used 2 and 3 port valves and with the latter 2 or 3 position.
Often instead of the thermostat controlling the boiler direct it actually controls the motorised valve which in turn controls the boiler. It is common for people to change thermostats and controllers when it is the motorised valve micro switches which are at fault.
This
is a typical wiring diagram however there are in fact more switches inside the motorised valve than shown and fault finding is not easy.
On some plans it shows a junction box and if all builders followed the plan to the letter and used the terminals the manufacturer selected in their plan it would be easy. However many would get a surface box and lid and used a strip of terminals inside and use their own plan requiring less terminals.
Also there are specials which would be nice would be a as built plan like this one
however it is rare to get one.
New central heating systems are easy the boiler has it all built inside so you know exactly how it is wired. But the old systems must be about the most complex wiring found in a house.
Again if installers used multi-cored cables with a colour code it would be great but often it is two or three twin and earth cables strapped together so you don't even know if a black wire is neutral.
I wish you the best of luck.
Show us a picture of it! You are not helping yourself here. We can only give information based on what you tell us! Nobody can find info on your boiler, and the stat instructions are only good if we know whats at the other end!
