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Discuss 2 Port Zone Valve - Clicking in the Central Heating Forum area at

  1. djbwilliams

    djbwilliams New Member


    Replaced a dead syncron motor in a Grasslin 2 port zone valve, however when connected back up & triggered by the thermostat it's now creating a constant clicking noise - caused by the actuator lever attempting to move towards the manual/open end.

    See this YouTube link for an example of the problem...

    Does anyone have any experience of a similar problem or how to resolve? Is it likely the whole Actuator/Valve needs replacing? (Opens up fine if I put it in the manual open position, but doing that doesn't make the micro-switch trigger the underfloor heating pump)
  2. EvilDrPorkChop

    EvilDrPorkChop GSR

    You've either not put the motor in properly or the head mech is completely knackered. If so the head will need replacing, however if the back is stiff to turn once the head is removed this could be the cause of the issue. However seeming it's UFH the head has probably been open long periods of time and worn out due to usage.
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  3. Best

    Best Trusted Plumber

    Teeth on the arm part the motor cog meshes with might be worn.

    Really should only replace the syncron motor in actuators that are not old and badly worn.
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  4. djbwilliams

    djbwilliams New Member

    I had a similar problem about 18 months ago & the plumber supplied & fitted a replacement valve for about £200... just a tad annoying to shell out £200 every 18 months for something that I thought I may be able to fix myself as I'm fine with electrics (not knowledgeable enough to replace complete valve myself though)

    I will try removing the syncron motor again & reseating it, but as a next step would you suggest getting a replacement actuator or when you say the head may need replacing does that mean the whole valve likely needs to be swapped out? (in which case I'll likely get on the phone to the plumber!)

    I don't suppose anyone knows if a Grasslin actuator can be swapped for a Corgi/Honeywell model as they look the same?

    Tempted by the Drayton valves as I see the actuators can be swapped out with a 'snap on' installation, so if this is going to be a regular thing it may make replacing easier/cheaper in the long term?
  5. EvilDrPorkChop

    EvilDrPorkChop GSR

    Has he not replaced with a Honeywell valve? Honeywell ones are usually pretty good and will last. Not overly keen on the Drayton valves as had issues with the microswitches sticking. At the end of the day it's only two screws which hold the head to the body anyway.

    Any valves if they are open for long periods of time won't last, zone valves are designed to be operated 24/7 and hence will burn out/fail quicker if they are used like that.
  6. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    Bin the Grasslin mate and fit a honeywell .
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  7. djbwilliams

    djbwilliams New Member

    Do you know if Honeywell heads are compatible with Grasslin body if I go down that route?
  8. EvilDrPorkChop

    EvilDrPorkChop GSR

    No you need a Honeywell body.
  9. Ben-gee

    Ben-gee Plumber

    When you get the plumber in to exchange the valve ask him to put a full bore lever valve either side of it- this will make future changes much quicker and therefore cheaper.
    Ask him on the phone when you engage him then he’ll bring them with him.
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