Thank you everyone for your advice and comments. I will be getting my local electrical engineer to do the wiring and installation of the Room Thermostat in the near future. Just one more question on this topic - I know how to set a Room Thermostat to the temp I like - and I like to be warm - but do I set all TRVs to max. so that the Room Thermostat is the main modulator? Oh, I did enjoy reading all your replies - even though you did all confuse me, a novice, with your disagreements. Makes me wonder about paying a PRO to come into my home and do a safe and legal job when there are - evidently - so many varieties of the legal situation regarding CH in a domestic home!