Motorised valve query

Discussion in 'Plumbers' Talk' started by constuction man, Sep 9, 2019.

  1. Hi all. Noticed a couple of weeks ago that a couple of radiators got warm when running hot water for a bath. Last night the heating wouldn't come on. I presumed and after a bit of googling it was the motorised valve.
    So this morning I have replaced the synchronous motor within the valve.
    Heating will now come on when demanded.
    Trouble is that when the hot water demands heat for the tank the heating comes on as well!
    Have I not done something correctly or missed the problem all together?
    I hope somebody can help
    Thank you
    harrisjohnpaul likes this.
  2. Hans_25

    Hans_25 Well-Known Member

    Is it wired up correctly? If its an S plan system ( 2 x 2 port valves) I wonder if the orange wires from each are going to the right place.
  3. Mike83

    Mike83 Well-Known Member

    The body of the valve is probably passing.
    When the heating is on by itself you wouldn’t notice.
    But if the water is on by itself and done rads heat then it’s probably the valve passing.
  4. Thanks Hans. No it's not s plan.
    Hi Mike. What do mean by passing? Do you think the whole valve needs replacing?
  5. Mike83

    Mike83 Well-Known Member

    It’s passing some water when it should be fully closed.
    Like a sink tap not fully turning off.
  6. Mike83

    Mike83 Well-Known Member

    Usually the complete valve needs changed.
    You can usually feel if the pipes start to heat up after the heating zone valve.
    Do this with only the hw turned on
    The Teach likes this.
  7. Thank you for the replies. Looks like something to advanced for me so I gave arranged for a plumber to have a look
  8. The Teach

    The Teach Well-Known Member

    Often better to engage :rolleyes: a heating technician rather than a plumber ;)

    its an easy job for an experienced person,maybe consider exchanging all the zone valves at the same time;)

  9. harrisjohnpaul

    harrisjohnpaul New Member


    we always change the whole valve instead of just the motor because the ball that swings between heating and hot water can get stuck and needs greasing. So the ball is stuck hence why you are having the problem.

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