Bal Merino

the pump did stay on. Tracked it back to BOTH micro switches in the two zone valves were sticky!! took a while to spot it as once i fixed the first one (CE), everything seemed OK with everything stripped down. When i put things back together the same problem happened, only this time the boiler and the pump came on! So stripped down the other (HW) zone valve and found its micro switch sticky. it is actually worse, so i shall have to replace it (i have a spare) unless electrical cleaner. works. Thanks very much for the assistance, is was most appreciated.

BTW, it is not a combi system, just a boiler.

i have removed the timer plate, so it is not switching things on, the room stat is on low, the zone valeves are off, but the pump is still on. there is mains on pins 12 and 13 of the JB. So yes, the pump is on all they time. lucky elecctrical supplier. There is nothing behind the white plate to the left. The zone switches go via wall junctions covered by plates, as can be seen in one of the pics.

Sorry folks for miss-typing, CE =CH= Central heating. thanks for the super fast replies. its a Worcester Greenstar Danesnoor utility 12/25 oil boiler, there is only one pump (Grundfos ups2 15-50/60); unless the boiler also has a pump, there are separate zone switches for CH and HW, both appear to be working corretly (I changed the microswitches when i moved in). The boiler and timer is in a utility room, which backs on to a hall cupboard in which the pump is along with an interconnection JB. if i leave the mains switch on, but remove the timer moduel, the pump still runs. I feel I just need to move the pump live to a different terminal but wondering if that should be to one off the zone vales or to the boiler live terminal, the patter seems more applicable. I am an elcetrical engineer, so can trace where everything goes, just wonder what is best practice here. cheers.

Moved to this house 5vyears ago, gradually fixing previous work. Been trying to sort out noise from CE, finally realised the pump is wired so it is alway on. Would like advice as to best part of the circuit to connect it to so it only comes in when the system is calling for heat.