Motorised Valve Problem

[senoj]

I recently had a problem with my central heating and the motorised valve made a buzzing sound and began getting very hot. Eventually the valve stopped working all together and i replaced the actuator (potterton mpe322 three-port). This seemed to solve the problem (for about 2 days) but now the valve has started getting hot and buzzing again. I took the actuator off the valve and started to change the controls on the programmer. i found the following: when i turn CH on only the actuator moves through 90° and the pump starts, when i turn off the CH with the HW already off the actuator does not move and starts to make a buzzing sound. Also the valve seems to be quite hot in normal operation, is this normal?
I have looked at a wiring diagram and the wiring is all as it should be so i think i can rule out a wiring problem. Could this be a fault with the programmer(lifestyle lp112) or is something else causing this? i hope to get this sorted soon as i don't want the new actuator to burn out.

thanks in advance, Andy

 

[gas4you]

When you took the actuator off did you check for free movement of the spindle it fits on and turns

 

[senoj]

thanks for the quick reply,

the spindle moves freely

 

[MANDATE]

If you turned the CH off when the HW was already off the valve does not return to the initial start position. Power is still applied through the grey wire from the HW OFF terminal to the motor and holds the valve at the CH position. This is how it is designed to function. I gather the buzzing is caused by the motor.
To prove it, turn the CH off first followed shortly by HW the motors power will be cut off and motor/valve will drop back to initial start position and buzzing will cease.

 

[senoj]

thanks for that, i will see how it goes