hi can anybody help need to change central heating/timer at the moment ive got one that works hotwater only/ central/hotwater together. the timer is in the airingcuboard the system is a y plan with a 3 port motorized valve cylinder stat ,frost stat ,and a room stat. looking to upgrade to independant control of heating and hotwater. is it case of altering the wiring to suit the new programer or is there plumbing involved