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Vaillant Ecotec Plus 428 S53

Discussion in 'Plumbing and Central Heating' started by jackthom, 26 Sep 2020.

  1. jackthom

    jackthom

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    In my open vented Y plan system when heating up only the DHW cylinder with the boiler flow somewhere around 70C the S53 code is regularly appearing if the CH is then turned ON. The system is clean, the pump is healthy (set to max speed) and flow is good even when only DHW is being heated.

    I can only think the sudden inrush of cold water at the return is not quickly enough reflected in the flow temperature so the boiler thinks there is too wide a temp difference, ie insufficient flow when the opposite is probably the case.

    Has anyone had any similar experience of this, or any suggestions other than ditching the Vaillant and getting an Intergas?
     
    Last edited: 26 Sep 2020
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  3. picasso

    picasso

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    The 428 is a fairly big boiler, you could try down rating it depending on how big your system is and see if it helps, a stronger pump would probably help as well.
     
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  4. jackthom

    jackthom

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    Yes its output is too much for the house, I’ve honestly no idea what I was thinking when I had it installed 14 years ago.
    I have set d0 to 18kW and the boiler behaves fine under all other circumstances.
    It’s only ever caught out (when flow is already at higher temperatures) by the rush of cold water when the heating circuit is opened, mostly when the CH has been off for some time.
     
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