Remove wires from timer .
Live goes to live neutral goes to neutral
From live link to 2 and 5
Then from old timer put 4 of old timer into 3 of nest =ch on.
Then 3 of old timer into 6 of nest =Dhw on
Then 1 of old timer to 4 of nest = Dhw off.
Remove wired room stat and connect common and sl...
It is to do with your controls
If you have a s plan. Or y plan system with a hot water cylinder in airing Cuboard. Dhw is first priority.
So it will heat the coil up first before going to rads. Depending on times you've set. I'd advise to turn Dhw demand off if you have it on in evenings and...
Problem I find is the wiring centre I have there has one wire coming into the room stat side of pcb.
And what if customer wanted it as a wired installation ?
Isolate one of the radiators downstairs that don't work. On both sides remove the radiators and slightly open the valve to see water flow
Ifrom water is blackish or brown I'd advise you to get a good power flush.
I know how to install a nest 3 on standard s plan or y plan ect. But what throws me off is the new esi controls they have in new build anyone know how to get past this and install ? Any advice would be appreciated.