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Strange boiler issue- can anyone explain?

Discussion in 'Plumbing and Central Heating' started by xpeterpx, 21 Aug 2017.

  1. xpeterpx

    xpeterpx

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    Hi all

    bit of a strange one for you!

    Just on the verge of ordering a new combi boiler to replace the old Vaillant WCW242 after it was diagnosed with pcb board issues and it just cuts out when the hot water is put on full pressure
    Anyway, just realized that if I put the hot water on just on low pressure initially the boiler fires on fine,turn the pressure up once the hot water starts flowing and we have running hot water for as long as we need?
    But if I put the hot water on full flow straight away it just cuts out again (ignition light comes on)
    Can anyone explain why this would be and are we realistically looking at a new boiler eventually at some point anyway?
    Thanks for any views on this curious one

    Pete
     
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  3. Smithy the plumber

    Smithy the plumber

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    Hi Pete don't think you have a faulty PCB ! more than likely a diverter valve who told you it was the PCB ? if you have very high water press then fit a pressure reducing valve
     
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  4. xpeterpx

    xpeterpx

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    Many thanks. To be honest I would have thought the boiler would not work at all if it was one of the pcb's? We had a heating engineer out on home insurance. He mentioned there are 4 pcb's on this boiler but could not say which one was at fault
    Regarding the pressure reducing valve are they unique to the boiler as Vaillant dont make parts for this old boiler
     
    Last edited: 21 Aug 2017
  5. Smithy the plumber

    Smithy the plumber

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    Right hand side of boiler is a plastic cover this covers the micro switch for hot water due to wear the screw may not be making full contact but more than likely the rubber diaphragm in the diverter valve is weak and needs replacing should still be available (Part 01-0457) may even have some at home, the other common one to go is the diaphragm in the water valve below boiler, (01-0318) only thing is you may have to buy as a kit now but both can be done
     
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  6. AGAS

    AGAS

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    Get a different engineer the clueless Idiot ;)
     
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  7. AGAS

    AGAS

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    There are other things to check on this boiler for this fault. but checking the pin travel is a start I suppose
     
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  8. Smithy the plumber

    Smithy the plumber

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    As you say other things to check, but boiler is working but slow to fire on hot water, with out seeing it I would start with water valve , good boiler but tight for working on, would think diaphragm's were still available.
     
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