On the same theme, I have a combi boiler with all radiators in the house having TRVs. For efficiency, should I set the boiler temp to high so very hot water is going to the rads which will then ‘click off’ earlier, or have the boiler temp set to medium?
In other words, if 3 on a TRV vaguely represents a temperature which I believe it does, should the feed into the rads be hot or does it have no overall effect?
I guess I should test it – have all rads set to 3 and then set boiler to high and see how often and for how long the boiler fires, and then set boiler to medium and compare.