Vaillant Ecotec Plus 937 problem

Discussion in 'Plumbing and Central Heating' started by mrkjd, 9 Feb 2009.

  1. mrkjd

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    Our Ecotec 937 has stopped working this morning. Error Code f81.

    It was installed and commissioned approx 8 months ago and has been working fine. The installer filled out the required details and signed off the installation. This morning we had no hot water and on checking the boiler noted the error code.

    I've read past posts on this subject and it seems this model has a known problem concerning the PCB leading to the boiler displaying this code error. Could somebody explain to me what exactly this code means and why the PCB is diagnosed as the culprit? Will a replacement PCB sort this problem? Has this been documented as a final fix or is this error code an ongoing unresolved issue on this model? I'm concerned that if the problem relates to the unvented tanks on this model then the engineer may just bypass this function and claim all is well!

    Our Vaillant room thermostat has also developed an error code BMU Err which I assume is related?

    We have an engineer coming out on Weds which means no heating or hot water until then. Thanks Vaillant - nice product!
     
  2. Agile

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    If we had fitted a boiler we would come out first and see whats wrong and if we can get it going until the warranty engineer can attend.

    Other people please note that even Vaillant can take three days to come out at busy times.

    It seems that you have already read up about this fault and I dont think there is much that can be added to what has already been said.

    Tony
     
  3. mrkjd

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    Thanks for the reply Agile but I disagree - I have asked specific questions in my last post that I was unable to find answers for:

    What does Error Code F81 mean?
    Why was the PCB diagnosed as the culprit originally?
    Have the "new" PCBs resolved the known issue?
    Is there an ongoing unresolved problem with F81 codes?
    Is the BMUErr code on my Room Thermo related to the F81 error code?

    If you can't answer these perhaps others may?

    I am concerned that I have an unreliable and problematic boiler which instead of giving me years of trouble-free service is going to be a dog. I am concerned that Vaillant, who are supposed to have a good reputation, have a model on the market which is not fit for purpose suffering from continued known problems. If the above questions are answered I may be able to rest assured that these concerns are unfounded.

    Finally, the heating is still working so the problem is confined to the HW system only
     
  4. dangermouse46

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    F81 and F91 are well documented and are usually cured by changing the shift load pump and pcb. (non return valve sticks and a sofware error).

    resetting the boiler will restore hw.
     
  5. Tipper

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    Have a look in your instruction manual, page 51.

    F81 in mine states:

    APC loadpump fault connected to F91

    F91 says:

    Sensor error on shift load storage tank module (NTC)

    There are various items to check for both faults and are to do with charging the water storage back-pack. It could be as simple as a loose connection associated with the temperature sensor or charging pump.

    BTW I have found in the past that installers don't make good fault finders (no offence meant guys :eek: ) so you are probably best to wait for Vaillant who will be quicker to find the problem and will probably have seen it all before.
     
  6. mrkjd

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    Is resetting the boiler something we can carry out? I can't access the user manual right now as I'm away from home and will have to relay instructions to the missus.
     
  7. dangermouse46

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    the reset button is a flame symbol with a X on it. (top left button below lcd display)
     
  8. dangermouse46

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    there are many things to check with F81/F91, the ntc harness that runs from the pcb to ntc is another one.

    I am not an installer btw Tipper.
     
  9. gas4you

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    Press the top left button, the one with the flame with a cross through it.

    Call Vaillant out under warranty.

    Obviously this fault has not been erradicated as we are led to believe :rolleyes:

    The 'BMU err' is just a code telling you the boiler has locked out.
     
  10. David937

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    :eek: Do you just happen to be a person with a lot of knowledge of Vaillant products.
     
  11. dangermouse46

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    I am a heating engineer but specialise in boiler repairs and servicing, used to install but now just do the odd boiler change here and there.
     
  12. David937

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    Ok, thanks for telling me.

    I hope my boiler doesn't develop this fault. :rolleyes:
     
  13. Agile

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    This boiler was installed eight months ago!

    It may have been lying around in a merchants for a couple of months too.

    Are you sure that it would have been post-modification?

    Tony
     
  14. mrkjd

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    Thanks guys for the reset instructions. Missus now has HW again and Vaillant engineer will be out on wednesday.

    Agile, yes boiler was installed 8 months ago but it did not "sit in the merchants". They had no stock and had to order from Vaillant. I'm not sure when the F81 fault was diagnosed to the PCB and 937s modified but you seem very defensive of Vaillant.
     
  15. Agile

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    I can assure you that you have misinterpreted me there!

    There is no connection between me and Vaillant and most boiler manufacturers would consider me quite outspoken rather than defensive.

    All I intended to convey is that this is a known fault which was well documented on this forum and has been dealt with by a modification.

    Dave will have a better idea of what manufacture date will have incorporated the new PCB etc.

    Tony
     

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