Lurch wrote:

If it is an S plan there should be the boiler flow coming into the
airing cupboard, through the pump, then teeing into two valves. The
outlet of the heating valve will go into the heating flow. The outlet
of the water valve will go to the HW tank.

The boiler, cylinder, pump and valves are all located in a large airing
cupboard on the first floor. The piping and wiring are complicated by
the addition of a large pump for a power shower in an en suite that
takes a seperate feed off the tank - there are a lot of pipes and wires
in one place!

Is there anywhere i can get good wiring/plumbing diagrams and an
explanation of 's' plan for reference?