25th Feb 2019 original post, would expect he has sat his exam by now? I will admit I have looked at central heating wiring for non modulating boilers and simple enough, but as soon as a modulating boiler is involved then it starts to get complex.
Turning off a modulating boiler because your going out to work, or going to bed is simple enough, but what you don't want is to turn a boiler off/on by an external control rather than let the internal controls modulate the boiler.
What we want is a thermostat which will not cause the boiler to cycle on/off either the TRV wants to control through the water temperature or by connection to the ebus of the boiler. Better if latter is used, so you can only use one ebus thermostat on a boiler, so if split into zones, then the two thermostats has to be some how blended or changed according to if one or two zones are used.
