WHITE WIRE IS CONNECTED TO SITCHED LIVE OF ROOM STAT.
GREY WIRE,USUALLY CONNECTED TO TERMINAL 2 OF CYLINDER STAT
(SAME TERMINAL THAT IS WIRED FROM PROGRAMMER-H/W OFF)
THE ORANGE WIRE IS YOUR SWITCHED LIVE WHICH THEN GOES TO
THE BOILER
top of the evening
a new boiler and unvented? cylinder wouldnt sort your morning
pressure problems.with 24kw and only 4 rads your best option
would be an indirect hot water cylinder fed from cistern,possibly pumped,
from the loft above you.