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Pump constantly running - no boiler demand

Discussion in 'Plumbing and Central Heating' started by cabinman, 29 Apr 2013.

  1. cabinman

    cabinman

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    Hi,

    The pump on my system has recently started to keep running 24/7, regardless if there is any demand for CH or DHW.

    Pump = Grundfos UPS2 15-50/60
    MV = 2 x Honeywell Model ?
    Boiler = Vaillant ecoTEC plus 428

    Searching on the forum, suggests the MVs could be faulty - however, the pump is wired directly to the boiler itself - the MVs go to a Vaillant VR 65 Wiring Center - with a Vaillant VR 360F Wireless thermostat.



    So I am not convinced that one of the two Honeywell MVs are at fault? (They have the little bump on the casing, so can be replaced without draining down - so that is one option I guess!)

    Any ideas? Thanks in advance :(
     
  2. petertheplumber12

    petertheplumber12

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    Sounds like the boiler is doing something it shouldn't. you need to get the wiring and the boiler checked by either an electrician or a suitably qualified gas safe engineer. The boiler gives the pump a 2 minute pump overrun and it could be faulty PCB.
     
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  3. Boilerman2

    Boilerman2

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    The Valves control the Boiler only, the Pump is controlled by the Boiler, therefore it follows that the fault lies within the boiler possible PCB fault? ;)
     
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  4. 45yearsagasman

    45yearsagasman

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    If your system is wired as a standard S plan then you could check that both the orange wires from the MV's are 0 volts (when system off) and thus proving the valve end switches are OK.
     
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  5. cabinman

    cabinman

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    Thanks all for the speedy responses.

    @ 45yearsagasman - yes, this is an S-plan, so great - I will use a multimeter to check the output of the orange wires from the MVs (which are not connected in the wiring center, neither is the grey) to at least put them out of the equation.

    Should it be a PCB, I assume this comes with hefty price tag :?:

    [I should also add, that the pump was newly fitted by AA insurance and it worked fine for some weeks, before developing this issue]
     
  6. cabinman

    cabinman

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    Just in case it turns out to be the PCB - I recon this is the correct Vaillant Part Number for a ecoTEC Plus 428?

    0020036861

    As a side note, would this be covered under insurance? Just realised I could save a pretty penny like that! :)

    Thanks for all the advice :)
     
  7. PlumbGas

    PlumbGas

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    Most insurance policys cover PCBs yes
     
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  8. mogget

    mogget

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    If the 428 uses the same part as the 418 (and I think it does) then that is the correct part.

    EDIT: Just had a look at the catalogue and that is indeed the right unit.
     
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  9. onlyfitidealboilers

    onlyfitidealboilers

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    A spark !! Give me a break. If you carn't wire up a heating system your in the wrong trade Pete.
     
  10. cabinman

    cabinman

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    Appreciate you looking that up mate - cheers :cool:
     
  11. TheAA1

    TheAA1

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    Hello Cabinman, we’d like to address this with you, if you have any outstanding queries, please email the details including your full name, address and policy number to chat@theaa.com with Reference FOR40991. Regards, the Official Representative of The AA.
     
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  12. cabinman

    cabinman

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    Thanks all, PCB was replaced - pump now behaving as expected / back in control of the boiler.

    :cool:
     
  13. Nigel1

    Nigel1

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  14. neiltheplumber

    neiltheplumber

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