Central Heating control valve

Discussion in 'Plumbers' Talk' started by Theo70695, May 24, 2019.

  1. Theo70695

    Theo70695 Member

    The three way actuator on my control valve is attempting to change the valve setting but failing. The reason that I think that the attempt is being made is that I can see the worm drive turning a little bit when I set the hot water to heat the cylinder and then it stalls. The valve is a bit warm but not dangerously so, and there is a low buzz from it.

    It would seem then that the electronics might be OK. Could it need resetting in some way? I suppose that it might have got confused as to the actual position of the valve and is trying to push it beyond its normal mechanical limits but it's likely that the valve itself is seized. Is there anything that I can to to free it off?

    One further bit of information that might be relevant: with time switch set to CH only the CH and the HW get hot. Same when the time switch is set to HW only.

    The box which covers the actuator mechanism has this information:

    MID POSITION ACTUATOR CODE
    BGMVSP-23

    BRITISH GAS NP-C CODE 555312

    Any thoughts gratefully received.

    AFAIK the system was set up about 11 years ago.

    Nick
     
  2. Mike83

    Mike83 Screwfix Select

    The brass spindle has probably seized.
    Remove the actuator from the brass body by pushing the black clip on the side of the actuator.
    If you can’t turn the spindle with your fingers then it’s seized. You could try turning it whilst lubricating it.
     
  3. Theo70695

    Theo70695 Member

    Thanks. It needs a spanner to turn. I will try some oil.

    N
     
  4. Mike83

    Mike83 Screwfix Select

    A little oil and keep turning it.
    It may ease off.
    Sometimes they go a little stiff but the motor can still overcome it.

    You can turn the heating and water on and off with the actuator removed. You can then see if the mechanism operates correctly.
     
  5. Theo70695

    Theo70695 Member

    Thanks for the advice, Mike83.

    I have freed off the valve and can now turn it from one extreme to the other with my fingers. I was surprised that the travel wasn't further. It's only turning about 20 degrees from one extreme to the other.

    Still not working properly so I took off the actuator and switch on the system first with just the HW and then with just the CH. The actuator socket didn't move.

    Question: Is the most likely problem the actuator or should I be looking somewhere else? I am loath to remove the actuator to give it a bench test. I have no wiring diagram for it so I haven't any idea how I could test it. My plan is to by another and fit it by changing it over wire by wire and hoping that the colour coding hasn't changed!

    Good plan?

    N
     

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