After trawling through some older posts on here to tidy up images & content following the recent relaunch of my site, I thought it might be useful to make copies of the wiring diagrams I used to sort out our central heating system.
The diagram set includes wiring plans for a number of popular configurations of central heating systems, C Plan, W Plan, Y Plan, S Plan, S Plan+ etc. and you should select the most appropriate diagram that matches the components you have installed in your system along with what you're hoping to achieve in terms of controllability.
Obviously your milage might vary and if you're unsure as to how to proceed I'd strongly suggest you stop reading here and go find yourself a competent plumber to advise.
This is a diagram for a C Plan system - a fairly typical UK pumped & zone-controlled heating/ gravity domestic hot water system including a wall-mounted thermostat, hot water storage tank thermostat and time controller. Click the diagram to download a PDF of the diagram which will print better!
If C Plan doesn't fit your needs, click here to download a PDF containing diagrams for other popular systems.