Ok,
My issue is that the Drayton ZA5 port on the central heating circuit does not shut off , either when the correct temp has been reached on the wall thermostat or if I manually switch the heating off from the programmer.
What actually happens is that the valve makes a very loud clanking noise (like its jammed) and it fails to shut off.
I thought this must be the valve itself sticking as opposed to the actuator, but I removed the actuator body from the valve and can turn the spindle quite freely.
What seems to be happening to me is that if the pump is running then the valve will not close properly due to the pressure from the water (its only about 2 foot from the pump), so is the sequence of events as follows ?
C/H no longer calling for heat, signal to valve to switch off, micro switch first stops pump running and then closes valve.
Its an odd one because it only happens now and then, have had the issue for last week and had to turn off power to stop it running when I am out.
It is working fine now but I know sometime soon it will stop again.
By way of a test I removed the valve body, switched the power on and set the programmer off. Even with the valve head off, the programme off, the pump was still running and when I tried to manually close it I got the clanking noise (pressure too much I guess).
I refitted the valve head and now all ok, but I know it will break soon.
So it either must be faulty microswitch not turning boiler off first, or the pump has intermittent wiring problems making it run when it should not.
The boiler by the way is an old gloworm 30ff thing, has brand new pcb but the issue with the pump/valve was before the replacement so have ruled that out.
I am guessing a new head may fix, but dont get why even with the valve head removed and the heating switched on I can still replicate the problem.
Any ideas or help most gratefully received.
My issue is that the Drayton ZA5 port on the central heating circuit does not shut off , either when the correct temp has been reached on the wall thermostat or if I manually switch the heating off from the programmer.
What actually happens is that the valve makes a very loud clanking noise (like its jammed) and it fails to shut off.
I thought this must be the valve itself sticking as opposed to the actuator, but I removed the actuator body from the valve and can turn the spindle quite freely.
What seems to be happening to me is that if the pump is running then the valve will not close properly due to the pressure from the water (its only about 2 foot from the pump), so is the sequence of events as follows ?
C/H no longer calling for heat, signal to valve to switch off, micro switch first stops pump running and then closes valve.
Its an odd one because it only happens now and then, have had the issue for last week and had to turn off power to stop it running when I am out.
It is working fine now but I know sometime soon it will stop again.
By way of a test I removed the valve body, switched the power on and set the programmer off. Even with the valve head off, the programme off, the pump was still running and when I tried to manually close it I got the clanking noise (pressure too much I guess).
I refitted the valve head and now all ok, but I know it will break soon.
So it either must be faulty microswitch not turning boiler off first, or the pump has intermittent wiring problems making it run when it should not.
The boiler by the way is an old gloworm 30ff thing, has brand new pcb but the issue with the pump/valve was before the replacement so have ruled that out.
I am guessing a new head may fix, but dont get why even with the valve head removed and the heating switched on I can still replicate the problem.
Any ideas or help most gratefully received.