On 20/10/2020 15:22, Andy Bennet wrote:
On 20/10/2020 13:17, Graeme wrote:
In message 2020101823510528942-nospam@nospamcom, John Smith
writes

Be careful wiring in the new head as if the board is anything like
ours it's rather small and easy to forget what goes where and to
accidentally set another wire loose.

I have taken multiple photos and drawn a wiring diagram, just in case :-)

What I'm not sure about is the two black wires which go into the
valve, from the cable to the boiler.Â* One black wire is connected to
an orange wire, the other to a grey wire.Â* Not sure whether it matters
which black wire is connected to orange and which to grey.


The orange and grey leads go to a NC microswitch. The switch closes when
the valve fully arrives at the open position. It does not matter which
way round you wire those leads but i'm sure somewhere ther must be a
convention. The blue and brown leads power the little motor and are
turned on/off by your thermostat. (for completeness the yellow/green
lead is the earth!)

I re-read the above just after I hit 'send'. Err the microswitch is NO
not NC!
soz