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Discuss Central Heating Fault, Motorised Valve? in the Central Heating Forum area at

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  1. Skiny

    Skiny New Member

    Bit of an issue with my central heating this past few days, it's struggling to come on and was wondering if someone here could give me an idea of what's wrong.

    When I turn up the temperature to trigger the heating, it often seems to fail. It's hard to say how often, because it can work fine for a few minutes whilst testing, but then minutes/hours later, I'll try it again and it will fail.

    One of the valves is making a strange buzzing and clicking/tapping sound - I'm not sure if it's normal, but I'm guessing not?

    When it works, I will hear the click of the thermostat, then a whirring of the valve and then the boiler comes on. When it fails, I hear the click of the thermostat and then nothing at all after. Turning the thermostat on and off a few times will usually turn the heating on.

    The noise seems to be coming from the bottom unit, as you can hear in the video.

    If it's relevant:
    Boiler is a Worcester Greenstar 12i system boiler (showing 2 bar / just under)
    Thermostat is a 3rd generation Nest
    Unvented cylinder as part of the system
    Every single component in the entire system is just a few months old.
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Yea sounds like the syncron motor has gone
  3. king of pipes

    king of pipes Trusted Plumber GSR

    As shaun has said the motor in the zone valve is failing should be a free replacement if its only a few months old ? Cheers kop
  4. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    As above ^^^

    , just under 2 bar . way too much , should be approx 1 bar when system is cold
  5. Best

    Best Trusted Plumber Top Contributor!!

    The toothed arm inside those Honeywell valves is sloppy and wears. They are poorly made IMO.
    You will hear a clicking sound and it will typically work intermittently for a few weeks or months, until failing totally
    • Agree Agree x 1
  6. Skiny

    Skiny New Member

    Thanks for the replies. I thought it might be the motor, I changed it earlier today. It's reliable now, in that it will turn on/off on command. However, the mechanism inside seems to operate slowly. Is this normal? Video below, you can just see the gold mechanism moving:

  7. Ric2013

    Ric2013 Plumber

    I think that's normal.
  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Yep standard

    There made for toque not speed
  9. Chalked

    Chalked Plumber GSR

    Bit like me , these days!
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