hw problem

Discussion in 'Plumbers' Talk' started by mrblobby, Oct 16, 2006.

  1. mrblobby

    mrblobby New Member

    I have the following problem. When the hw system is switched on (either manually or at programmed times), the mcb trips. However if switched on when I have the cylinder stat down on it's lowest setting, and then I turn the stat up, the hw system doesn't trip and the boiler lights up.
    What does this indicate ? I have already replaced the programmer and cylinder stat, so it can't be a fault with them
  2. chris roast

    chris roast Member

    check valve, if its y plan, its one valve, with 3 outlets, or s plan, with 2 valves, just 1 in 1 out
  3. mrblobby

    mrblobby New Member

    its Y plan. How do i check it? It flicks over from w-m-h properly and the wiring inside looks ok.
  4. mrblobby

    mrblobby New Member

    Sorry to bring up a previous post, but I haven't been able to get this sorted yet. My system keeps tripping also when i try and put on the CH from the programmer. If i turn on the HW by using the cylinder stat, then the CH will also work fine after that.
  5. M.I.G.

    M.I.G. New Member

    you need a Sparks not a Plumber!
  6. sinewave

    sinewave Screwfix Select

    MCB or RCD?

    Big difference!
  7. mrblobby

    mrblobby New Member

  8. sinewave

    sinewave Screwfix Select

    If yer RCD is tripping then you have a faulty Class 1 component that is leaking current to earth via the Boiler Chassis.

    Your programmer is a Class 2 component so therefore would not trip an RCD if faulty.

    Without being there it's next to impossible to say but a likely culprit may well be your diverter valve.

    BTW Boiler supplies don't need to be on an RCD as there classed as 'Fixed Equipment'! ;)
  9. mrblobby

    mrblobby New Member

    Thanks v much for your advice. If I disconnect the power to the valve, and then try turning the system on, should i then be able to identify if it is the faulty part? Then i just replace the synchron motor? or could it be the mechanical part that is casuign the problem.
  10. Spyder

    Spyder New Member

    It could not be the mechanical part. It's an excessive leakage of current to earth and not to the neutral wire.

    When the HW is off and the T/s is off, the grey wire is powered from the programmer.

    When the HW is on and the T/S is off, then the grey wire is still on but fed via the T/S. When the T/S is turned on, the grey wire goes off and the orange wire goes on and also the pump and boiler.

    From off, when the T/S is on and the programmer goes on, the grey wire goes off and the orange, boiler and pump all go on together.

    It could be that all three items being very inductive could be leaking at switch on and tripping the RCD. The RCD could be faulty.

    You really need to do an insulation test and thus need the services of a sparks.

    As they are cheap you could try changing the syncron motor but make sure you get a pucka one. Read the postings by Dick_Puller et al on chinese copies.
  11. mrblobby

    mrblobby New Member

    Thanks sinewave and spyder. i think i'll try changing the s/motor and then failing that get in a sparkie. Thks for all your help.

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