Right - new problem (but I think I know the solution)

Just got the 2 port valve, and when having a look at the wire noticed that
the white didnt have an inner core (just a the plastic covering).

After checking the lid of the valve the diagram shows there is a microswitch
which just connects grey and orange when the valve is open, thus we can fire
the boiler when the HW is ON.

Am I right in thinking that this valve cannot be used without the NC link to
the pump heating?

After opening up the valve, I note that the "dummy" white cable is cut
short. I then consider swapping the relay for a SPDT, and after looking find
that one is already fitted but not wired? (why???)

I cannot connect the white wire as it is a dummy! so will need to replace
the 1m or so of flex to make a connection to the white.









For this you will need a 2-port zone valve and a tank stat on the hot
water cylinder (if you don't already have one). An I right in thinking
that to wire I need to:

Connect thermostat HW On to: Valve Brown
Permanent Live to: Valve Grey
thermostat CH On: Valve White and Pump L

Boiler L to Valve Orange

plus neutral & earth


Thus, boiler gets power when valve activated (via grey)
Boiler gets power when valve off (via valve white)

Currently the boiler has a connection for the pump. I assume that
this should be left so that the pump can continue to run when the tank
theremostat is cycling.

The wire colours may vary, but if you study the Honeywell wiring diagram
referenced earlier, and wire it *functionally* the same way, you should
ok.