Radiator coming on with hot water

Discussion in 'Plumbers' Talk' started by Adam Taylor, Jun 10, 2018.

  1. Adam Taylor

    Adam Taylor Member

    Can anyone diagnose this?

    Towel rail in family bathroom, and radiator in en-suite have started coming on when the thermostat calls for hot water.

    Radiators are all off otherwise, as these two should be as well.

    Any ideas?

  2. Lawrie

    Lawrie New Member

    I had this problem, the three port valve had a build up of limescale on it and so was never closing the line to the central heating fully, this meant that hot water was leaking into the central heating systembut becuase of the low volume/pressure it was only noticeable on the first rad in the loop.
    I replaced the three port valve over two years ago now and the problem has never recurred.
    Adam Taylor likes this.
  3. Adam Taylor

    Adam Taylor Member

    Thanks lawrie. Any particular brand thats with getting or avoiding? Seems quite big price differences after a quick Google
  4. Lawrie

    Lawrie New Member

    I have a Drayton, I only replaced the valve itself not the actuator. The other cheap option is to take the valve off and clean it, I have done that before but it's an awkward job, there's not really any space in the pipe to get in there and scrub!
  5. Lawrie

    Lawrie New Member

    Should say I don't have experience with other brands so can't really offer advice on that front.
  6. dcox

    dcox Active Member

    I usually fit Honeywell although they can be pricey.
  7. teabreak

    teabreak Well-Known Member

    Just ceck it is that by turning off the bathroom rad to see if the fault moves to the next radiator before changing the valve.;)
  8. Astramax

    Astramax Well-Known Member

    If it's on the primary circuit it will do.
  9. teabreak

    teabreak Well-Known Member

    My thinking, or combi boiler "dumping" hot water in the heating circuit.;)

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