Faulty Programmer /Diverter valve head/Wiring

[RayPeck]

I have a fully pumped Y plan heating system using a Potterton EP2 programmer. Drayton MA1 Diverter valve. I have just replaced the Actuator head as the heating was not coming on unless I had the hot water switched on as well, I then shut down the tank thermostat heating stayed on.
When the programmer was turned off the diverter valved stayed on H. I removed the power to the Central Heating and the valve returned to W under spring tension.
Tested:
No Power Valve on W
Power On - Call for Hot water on programmer, turned up tank stat and boiler fired up.
Call for Central Heating on Programmer, turned up room stat and valve moved to mid-position.
Turned down stat on cylinder and valve moved to H
Turned down heating and cylinder thermostats and valve stayed on H
Turned off CH and HW on programmer and valve stayed on H - i would have thought it should have restored to W under spring tension.
Remove power to central heating and valve returned to W.
I have a feeling there is a problem with the programmer. any one give advice - my brain hurts
Thanks
Ray

 

[davesparks]

What exactly is the problem you are experiencing?

It looks to me like it is all working as exoected, assuming the boiler stops firing when all thermostats are turned down.

 

[RayPeck]

What exactly is the problem you are experiencing?

It looks to me like it is all working as exoected, assuming the boiler stops firing when all thermostats are turned down.

Thanks for replying, have done a bit more research on the valve _ Drayton Test Video for MA1 and as you say it seems to be working correctly, was concerned that the valve head was getting warm when turned off and sitting in the H position which I now understand is normal. Problem was that the heating would not come on when just calling for heating, had to start hot water as well.
Going to have a look at the diverter valve itself to see if it is not opening correctly.

 

[davesparks]

Yes the valve will sit in the H position when when hot water is on at the programmer, the cylinder stat is satisfied and the heating then goes off. It is held in this position by the satisfied signal from the cylinder stat.
The valve head will get a little warm in this condition as the motor is holding it open.


When the hot water channel on the programmer switches off or the cylinder stat calls for heat the valve will spring return to it's unpowered state.

 

[oscar21]

3 port valves are the devils work, why anyone fits one in a one off system I'll never know. 2x2 ports all the way, I can kind of get it if you are plumbing up a whole housing estate and you will save money on the number of valves. I wouldn't mind but you cant use a 3 port on a pressurised cylinder anyway, and if you do you have to fit a 2 port after it.