Hiya-am thinking about updating my CH system so I can have hot water and heating on at diff times. at the moment i cannot have for example hot water on from 6-8 amd heating 7-9, they have to be on together. it is an old drayton programmer. to replace it, will the wiring be the same, or will manu instructions with the new programmer explain how to re-wire? if its too much hassle i won't bother! but i'd like to change it over if able to?