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Worcester 350 combi boiler. CH cutting out, HW OK. Fan? Pump? Something else?

Discussion in 'Plumbing and Central Heating' started by nv_london, 20 Jan 2016.

  1. nv_london

    nv_london

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    ±+++++++++++++++++++
    This site does not permit DIY gas threads
    +++++++++++++++++++++
     
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  3. Agile

    Agile

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    You sound potentially very dangerous.

    A DIYer should never even open the combustion chamber as that's the room sealing that makes the boiler safe.

    You seem fixated on hearing or not hearing things.

    Your boiler can never fire up unless the fan is working! Your desire to just replace parts willy nilly seems very bizarre.

    The obvious solution is to call a competent engineer to repair your boiler.

    But be aware that your 350 is pretty old and well overdue for replacement. But it comes from a vintage where Worcester boilers were very solidly built and reliable. There are probably a few of them still in use.

    Tony
     
  4. nv_london

    nv_london

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    Thanks Tony, you’re correct – I am very dangerous.

    To be fair, I don’t think I’m replacing parts ‘willy nilly’, I am trying to think about the problem(s) and possible solution(s) and I’m also trying to get a better understanding of how the boiler works (i.e. I didn’t think the boiler could work if the fan was knackered – which you seem to agree with – but I find it very strange that I never hear it kick in).

    Equally, I know that my boiler is old but I do have it serviced every year and am a keen DIYer so I quite like trying to figure things out on my own (with online help). However, I will get it checked out professionally once I’ve completed any work.

    Any further advice on the issues with the boiler would be much appreciated.
     
  5. Agile

    Agile

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    We are not permitted by the forum rules to give advice on gas/combustion or safety related issues or to those who access sealed areas of the boiler.

    Nor do we believe anyone who says he will get anything professionally checked after a DIY repair as it would obviously be more cost effective and quicker to have the professional do the repair in the first place.

    Tony
     
  6. nv_london

    nv_london

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    Thanks, Tony.

    I should have checked the rules before posting and asking such questions.

    (I don’t necessarily agree that it would be quicker and cheaper to get a pro out in the first place – i.e. no labour costs, I may be able to get parts (for a discontinued boiler) cheaper independently, I may be able to carry out the work in a short time-frame) – Irrespective of this, I do completely appreciate the rules concerning safety and the sealed areas of a boiler.

    Bearing that in mind, as a completely academic/theoretical question, from the information you have, do you have any idea what could be wrong with my very old boiler?

    Thanks.
     
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  7. Agile

    Agile

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    We are not permitted to bypass the forum rules by pretending that it is only an academic exercise.

    There are many things a boiler engineer would normally check when fault finding a boiler and they have to be done at the boiler.

    But at over 10 years Worcester PCBs often start giving problems like yours. But a professional would only replace it after checking everything else.

    The last 350 I saw just before Christmas had a faulty PCB and the boiler was fitted in 1999.

    With the cost of a new PCB it would usually be considered false economy to make such an expensive repair to an old boiler.

    Tony
     
  8. nv_london

    nv_london

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    Thanks Tony.

    Reading around potential solutions for the issues I’m experiencing, I dismissed the PCB being at fault for a number of reasons - but I bow to your superior knowledge in this area.

    By the way, I know you’re not saying ‘IT IS’ the PCB just that it might be the PCB considering the age of the boiler.

    (I agree about the cost of a new PCB and the false economy it could create – but I actually do have a spare reconditioned PCB (both sections) but, don’t worry, as I said, I won’t be replacing it).

    I was almost hoping these issues had previously been experienced by others and that a common, almost obvious, fault could be highlighted.

    Thanks again.
     
  9. Agile

    Agile

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    """There are many things a boiler engineer would normally check when fault finding a boiler and they have to be done at the boiler.

    But at over 10 years Worcester PCBs often start giving problems like yours. But a professional would only replace it after checking everything else."""

    That is ALL I said !

    I will add that many professionals will not waste their time with "repaired" PCBs ( they are not reconditioned by the way ). Those doing them rarely have the facilities to 100% test them and there have been some cases of "repairs" being done by bypassing safety features.

    Tony
     
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  11. nv_london

    nv_london

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    Thanks again, Tony.

    I know that is ‘ALL’ you said – I wasn’t having a go at you and yet again, thanks for your ‘help’.

    By the way, I am surprised you’re telling me that my spare PCB is ‘repaired’ and not ‘reconditioned’ and that you can’t get reconditioned PCBs – I’m aware that there is a difference between the two words and their meanings and I have a work order stating what was ‘repaired’, what was ‘replaced’, what was ‘cleaned’ – and I have a 5 year warranty on it (altogether, I believe that makes it reconditioned). (I know that you’re going to write back saying that I can’t trust the work order and that cowboys carried out the work and that these same cowboys won’t be around in 5 years’ time should anything go wrong etc etc – so please don’t bother).

    In summary, thank you very, very much for all your help and advice, I now know; the forum rules on health and safety (which I didn’t know to start with), that anything could be wrong with my boiler (which I knew to start with) and that in order to properly diagnose the fault a pro needs to be physically present at the boiler (which I knew to start with). However, like I said, I was actually hoping to hear if the boiler issues that I’m facing resonate with anybody and if they could share their past experiences.

    I’ve just realised that you’re based in London…if you’re interested; you’re more than welcome to come and have a look at my boiler.
     
  12. ollski

    ollski

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    Driver pcb is an obsolete part and this range is being driven to obsolescence by Worcester quickly at the moment to the point I would be reluctant to be spending money on it
     
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  13. nv_london

    nv_london

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    Hi Ollski,

    many thanks for your reply.

    I completely agree, the PCB for this boiler is an obsolete part and the 350 has been discontinued (and hence, is very old) and throwing money at it may not be economically viable.

    However, I'd still like to understand why, seemingly, running the hot water would allow the central heating to come on? Unlike Tony, I'm not a (ex?) heating engineer/(ex?)professional/(ex?)health and safety guru or, generally, an (ex)pert (?), but I am curious to understand what's going on (and hence, what *could* be malfunctioning). I know, I know, just call a professional or buy a new boiler!

    Anyway, having done a bit of research on this it seems as though some people have indeed had exactly the same experience and issues e.g....

    http://www.diynot.com/diy/threads/worcester-bosch-350-ch-not-firing-up-but-hw-ok.241842/
    http://www.diynot.com/diy/threads/worcester-350-combi-boiler-no-ch-hot-water-ok.210028/
    http://www.diynot.com/diy/threads/worcester-combi-boiler-hw-ok-no-ch.9126/ (same problem, different boiler)
    http://www.diynot.com/diy/threads/worcester-350-boiler-cutting-out.80896/

    the last post is my personal favourite. It was posted in 2007 and even at that stage our very own Tony stated 'the boiler is getting rather old...blah, blah, blah, blah'.

    Frustratingly, nobody ever posted an outcome/conclusion - Time for a change hopefully...I will post back with my findings which, one day, will hopefully help somebody.

    (No doubt my next post will read 'I called a pro, they checked everything and said it was time for a new boiler'!)
     
  14. ollski

    ollski

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    If I was your gas safe man I would begin around ***other parts***** before I started worrying too much about the pcb, but the driver boards are notoriously flaky.

    *************************
    Parts names deleted by Mod
     
    Last edited by a moderator: 21 Jan 2016
  15. nv_london

    nv_london

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    Hi ollski,

    many thanks for the suggestions. Seeing as though the boiler wouldn't work without a functioning fan, if either the air pressure switch or the fan speed resistor were faulty wouldn't this mean that neither the hot water or the central heating would be working? (My issue at the moment is that the hot water works fine but the central heating, generally, doesn't - hence, I was assuming that the problem was specific for the central heating aspect of the boiler and not something communal like the air pressure switch/fan speed resistor......BUT maybe not? I too originally thought it could be a problem with the fan but, thinking about it, I'm now not so sure). I'm not saying that your suggestions are wrong, I'm just trying to understand if they're plausible. Apologies for my lack of knowledge. Like I said, I just like to understand how things work.

    Thanks again.
     
  16. Agile

    Agile

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    Quite so NV.

    But he was probably just giving a general comment and in no way related to your problem.

    In fact he was not even thinking of your particular model which does not have a fan speed resistor or two PCBs.

    Even so saying what he did lays his post open to be deleted by the site management as it could be construed as advising you do do work on which we don't advise.

    Even in 2007 it was still an old boiler. Now its an extra 9 years old.

    Tony
     
  17. ollski

    ollski

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    Not really sure what we are allowed to say on this foum anymore except that we cant tell you anything, best to look in your boiler instructions the sequence of operation is in there.
     
    Last edited by a moderator: 21 Jan 2016
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