Worcester combi boiler 28CDi

Discussion in 'UK DIY' started by barbara.collier@sky.com, Jan 19, 2009.

  1. Guest

    We have a Worcester 28CDi combi boiler that we had installed approx
    7/8 years ago. Last year we had a new heat exchanger fitted.
    We have been having rouble since Christmas. First we had no central
    heating and the pressure dial was all over the place, falling and
    rising, our installer came back and fitter a new pressure loop which
    then seemed to work ok. We then had trouble again with the pressure
    dial and leakage from the safety valve, the fitter thought the
    pressure dial was not giving the correct reaing and therefore the
    emergency valve blew. He came again and refitting the safety valve.
    We now have no hot water. When running the tap its warms up to hot
    and then goes cold. Whilst talking to the fitter on the phone, he
    suggested topping up the pressure and running the hot water to see if
    if now worked. Whilst doing this the boiler blew from the top valve
    with steam.
    He is suggesting that we might need a new boiler, but this seems to be
    a bit drastic.
    Can anyone give us any advice on what they think might be happening
    and what we can do.
    , Jan 19, 2009
    #1
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  2. YAPH Guest

    On Mon, 19 Jan 2009 11:46:42 -0800, barbara.collier wrote:

    > We have a Worcester 28CDi combi boiler that we had installed approx
    > 7/8 years ago. Last year we had a new heat exchanger fitted.


    Why?

    > We have been having rouble since Christmas. First we had no central
    > heating and the pressure dial was all over the place, falling and
    > rising, our installer came back and fitter a new pressure loop which
    > then seemed to work ok. We then had trouble again with the pressure
    > dial and leakage from the safety valve, the fitter thought the
    > pressure dial was not giving the correct reaing and therefore the
    > emergency valve blew. He came again and refitting the safety valve.



    Did he not fit a new pressure gauge, if that's what he thought was dodgy?

    > We now have no hot water. When running the tap its warms up to hot
    > and then goes cold.


    Sounds like the heat exchanger blocking up on the primary side. Why
    did you have the heat exchanger replaced last xmas? And if it was the same
    problem what was done to stop it recurring?

    > Whilst talking to the fitter on the phone, he
    > suggested topping up the pressure and running the hot water to see if
    > if now worked. Whilst doing this the boiler blew from the top valve
    > with steam.


    Sounds like the automatic air vent. What did you raise the pressure to
    (and how reliable was whatever you were measuring it on)?

    > He is suggesting that we might need a new boiler, but this seems to be
    > a bit drastic.


    Or maybe you need a new fitter :)



    --
    John Stumbles -- http://yaph.co.uk

    A: Because it messes up the order in which people read text.
    Q: Why is top-posting a bad thing?
    YAPH, Jan 19, 2009
    #2
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  3. newshound Guest

    Combination of Sod's law, clustering of random events, problems of combis
    once they get past five years IMHO.

    In the past month mine has:

    blocked a DHW HX (fixed)
    failed the ignition circuit on the main board (fixed)
    split a DHW flow sensor diaphragm (fixed)

    and in the course of all that, the auto air vent decided not to seat, so it
    was dribbling water. Took out the valve and cleaned off the scale
    mechanically; now it doesn't leak, or vent either. Waiting for a new
    one.....

    Oh, it's a Wickes / Halstead. But the preceeding Vaillant behaved much the
    same after eight years.

    Makes you think about signing up for BG service.....
    newshound, Jan 19, 2009
    #3
  4. Ed Sirett Guest

    On Mon, 19 Jan 2009 23:07:42 +0000, newshound wrote:

    > Combination of Sod's law, clustering of random events, problems of
    > combis once they get past five years IMHO.
    >
    > In the past month mine has:
    >
    > blocked a DHW HX (fixed)
    > failed the ignition circuit on the main board (fixed) split a DHW flow
    > sensor diaphragm (fixed)
    >
    > and in the course of all that, the auto air vent decided not to seat, so
    > it was dribbling water. Took out the valve and cleaned off the scale
    > mechanically; now it doesn't leak, or vent either. Waiting for a new
    > one.....
    >
    > Oh, it's a Wickes / Halstead. But the preceeding Vaillant behaved much
    > the same after eight years.
    >
    > Makes you think about signing up for BG service.....


    The new HX and the failed auto vent point to problems with the heating
    circuit. Possibly a failed expansion vessel then frequent tops up then
    corrosion then a new HX?

    Properly maintained a Vaillant should go 20 years except for the VUW 2xx
    (Turbo Max non plus [1]) which are only a bit better than a 'typical' low
    end combi.

    ALL combis have pressure vessels and this is one component is the /root/
    cause of a sizeable proportion of all combi problems.


    [1] black fascia, turquoise knobs , ladder of LEDs.
    --
    Ed Sirett - Property maintainer and registered gas fitter.
    The FAQ for uk.diy is at http://www.diyfaq.org.uk
    Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
    Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
    Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
    Ed Sirett, Jan 20, 2009
    #4
  5. geoff Guest

    In message <>, Vegelen
    <> writes
    >In the 28cdi there is a plate heat exchanger on the hot water on demand
    >circuit. Water passes through this exchanger to acquire heat.
    >If your water isn't getting as hot as it used to this component may
    >need cleaning or replacing. They are designed to last 5 years.
    >
    >Also this boiler has a primary heat exchanger (Gas to water).
    >
    >This exchanger should last 10 years, so is probably ok in most peoples systems.
    >
    >If your boiler is behaving irrationally it may have one or more faulty
    >components.
    >
    >Your pressure dial gives an indication of overall system health.
    >
    >I watched its behaviour change over time and informed the
    >
    >Worcester Bosch heating engineer


    They are fitters - not engineers

    They don't engineer anything, they replace parts


    >- this observation helped
    >
    >diagnose a faulty expansion vessell.
    >
    >This fault was present on my boiler at the same time as a
    >
    >faulty diverter valve ( We had lost hot water through our taps).


    Where else does it go ?

    >
    >Many people are now throwing away perfectly good combi boilers
    >
    >(along with their own hard earned cash) when they dont need to.
    >
    >
    >A little self education and observation about your boilers
    >
    >operation, helps to diagnose early issues your boiler may have
    >
    >Learn what your combi boilers pressure dial is for and how to make
    >
    >sure it is kept at the correct pressure.
    >
    >Learn to watch it periodically because it will change its behaviour
    >
    >when certain issues arise.
    >
    >
    >Get your boilers serviced regularly- to prolong boiler life.


    How so ?

    >
    >
    >If all else fails and you think your Worcester Bosch boiler has
    >
    >problems, call the experts out (Worcester Bosch) or find a good
    >
    >researched local independent gas safe service engineer that fixes
    >
    >your boiler type on a frequent basis.
    >
    >A little observation and a little work go a long way in life and
    >
    >could save you £'s.
    >
    >Look after your boiler and it will look after you.


    I read mine bedtime stories, what do you do ?


    >
    >url:http://myreader.co.uk/msg/1391140957.aspx


    --
    geoff
    geoff, Feb 14, 2010
    #5
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