combi boiler keeps losing pressure

Discussion in 'Plumbing and Central Heating' started by fitzy, 10 Oct 2005.

  1. fitzy

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    my combi boiler (worcester 9.24 electronic) keeps losing pressure i have checked all related pipework and radiators for leaks but found none.
    while the system is running the outside overflow pipe has a steady drip/flow coming throught it.
    when the the system is started say for hot water it makes a hell of a racket and i have to repressurize it and push the reset button before it will run can any one help thanks. :(
     
  2. DarkInferno

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    Found it!
    Probable case is faulty/depressurised expansion vessel, which sounds like it has gunked up the PRV seal too.
     
  3. meldrew's_mate

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    Fitzy, take the white front cover off and find the red expansion vessel, about 12" x 6". Locate the inflation point and stick a matchstick in it like you were letting down a neighbour's tyres (if you're stuck ask a teenage hoody for help). If water comes out you need a new vessel. If nothing, or just air comes out it may be salvageable.....

    ....Take a bike tyre pump and put about 20 good strokes into it, watching the pressure gauge. If it goes up put another 30 in, or stop when the pressure gets to 2 bar. Bleed the upstairs rads and recheck the pressure, pump more air in to bring pressure back to 1 bar.....

    ....Check the PRV outlet, if it still drips you need a new PRV. If not turn the heating on and watch the gauge as it warms up. If it goes over 2.5 bar wait for it to cool, then put 20 more strokes of air in, re-bleed to get pressure down to 1 bar, and re-try.

    If some is good, more is not necessarily better, so don't overdo this.

    Put the cover back on.
     
  4. fitzy

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    i have tried the expansion vessel and water is spraying out as you suggest i may need to replace it is this expensive and is it possible i can purchase one and do the job myself or do i call in an expert :?:
     
  5. Agile

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    Its a very old boilerand you should be planning to replace it!

    A cheaper solution is to fit a stand alone ex vessel on the heating circuit.

    Or as a temporary solution ( 12 months ? ) isolate a rad and take 8 litres of water then put it back WITHOUT bleeding, the air at the top will then act as the ex vessel.


    Tony
     
  6. thumper1

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    I have the same peoblem. May seem like a silly question, can I replace the valve assuming its the the same/similar to bike tyre valve<a silly question
     

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