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Central Heating not turning off

Discussion in 'Plumbing and Central Heating' started by acprc, 4 Dec 2016.

  1. acprc

    acprc

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    Hi all,

    Apologies that my first post is a request for help but I guess that's the nature of these forums. I have an issue that I can't seem to get to the bottom of and wanted to ask for some help.

    In a nutshell my central heating won't turn off without cycling the mains power to the boiler. It turns on ok and the hot water turns on and off but the heating just wont turn off. The heating has a new Honeywell powerhead and that will motor the valve open but only closed when you cycle power. The controller is a brand new Honeywell unit as well. All electrical connections have been checked for security etc and nothing appears damaged or loose.

    The back plate for the controller is the older universal one and the new controller fitted straight onto it. The only other thing is possibly the junction box for the wiring as that is still the old box.

    I am pretty sure that this is an electrical issue as the valve motors open and closed fine it just wont close without the power cycling to the boiler.

    Any Thoughts?
     
  2. lightning

    lightning

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    Did you change the brass body or just the head
     
  3. acprc

    acprc

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    Just the head
     
  4. dilalio

    dilalio

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    Remove head. Operate and lubricate valve spindle (gentle movement cw and ccw) and see if that works.
     
  5. oilhead

    oilhead

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    What model programmer did you have and what have you fitted? What is the model of the powerhead you have fitted?
     
  6. dilalio

    dilalio

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    Whilst head removed, initiate switching on CH and see if head motors accordingly.
     
  7. acprc

    acprc

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    Old Programmer was a Danfoss CP715 and the new is a Honeywell ST9400C. The new valve is a Honeywell 4043. The valve spindle is free. I know the motor in the head works to power on heating as I hear it, when turning off it doesn't do anything until I cycle power. Haven't had it off as the heating turns off to see if it moves, but as I say I don't hear the motor.
     
  8. dilalio

    dilalio

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    Well it sure sounds like a wiring issue! Time to get the multimeter out!
     
  9. acprc

    acprc

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    Yes, process of elimination I guess!
     
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