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Vaillant Ecotec Plus - Pump overrun when restarting

Discussion in 'Plumbing and Central Heating' started by Teebob, 2 Jun 2016.

  1. Teebob

    Teebob

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    Hello everyone and thanks in advance for any idea you may have on my problem.

    Here is the situation. My boiler is a vaillant ecotec plus (combi) connected to a a series of radiators and a water tank with a "Y" scheme. Boiler works fine. The only problem is it wont "restart" while it is still hot and constantly goes into pump overrun. By "hot" I mean basically less than half an hour since switched off. This obviously causes an issue for instance if the thermostat is near its temperature (in which case the boiler would normally go on and off regularly). I have made a video showing the issue very clearly (with a target temperature of 55 degrees) which you can see here . The problem can be seen near 1'20''.

    Basically the boiler makes a normal start until it reaches 55 degrees. Then it stops for a couple of seconds (why?) while the pump is still running (temperature goes back down a bit). And then the boiler goes back on at full speed. Temperature goes back to 55 quite quickly and then continues to increase until 57 where the boiler goes into pump overrun (security mode).

    I had a few professional plumbers having a look. First told me to change the whole thing. Then got told to not change anything on the basis that we could live with it as is. Recently was told that it could be an issue with the heat exchanger / pump / blocage. I had the system drained - then a power flush. Then a new pump installed. But still the same problem. I am now thinking more about an issue with the boiler itself. Maybe a sensor doesn't work properly. Although it seem the work fine when starting from a cold boiler. I also had some doubts about the expansion vessel (cannot get any air from the valve) but pressure seems ok so not sure it is actually a problem. The only last piece we didnt change is the 3 port valve (which seems rather rusty) but dont see how it could be connected with the problem.

    Any idea?

    Thanks a lot
    Teebob
     
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  3. picasso

    picasso

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    Blocked canoe filter at a guess, the temperature is rising far too quickly showing poor circulation.
     
  4. Teebob

    Teebob

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    Thanks picasso. Whats the best way to check / clean / change the canoe filter? Does that come with the heat exchanger?
     
  5. picasso

    picasso

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    Its not a diy job, try and find someone that knows vaillants.

    edit... I am not an expert on vaillants so its possible you could get a different (correct ?) opinion from the proper guys.
     
    Last edited: 2 Jun 2016
  6. AGAS

    AGAS

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    it does look like similar to sensor fault also as above their is heat rising quite quick which indicates circulation problem . our resident valiant experts will advise i expect ,the pump sounds like its doing its job. you can't be messing within the boiler thou mate , you may need to put vaillant in your title so they can see it.
     
    Last edited: 2 Jun 2016
  7. Steelmasons

    Steelmasons

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    Hoses are choked and as Picasso says canoe filter possibly blocked..
    F.75?.....does temperature show an increase/decrease @ display when adjusting temp control knob?
     
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  8. AGAS

    AGAS

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    that was what i was wondering
     
  9. Steelmasons

    Steelmasons

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    Let's hope Agile reads this thread......any input on Agiles part will have Vaillant amending their MI's yet again...
     
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  11. AGAS

    AGAS

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    :LOL:
     
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  12. Teebob

    Teebob

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    No 75 fault. All I get is S.7 pump overrun. When I increase the temp at the control knob I can see the display changing and then the boiler would react by increasing its temperature. However if I reduce the temp on the knob then the boiler would go into pump overrun and I would have to let it cool down again. Display works fine either way.
    Thanks a lot for all your answers. I guess I will have to get Vaillant to have a look.
     
  13. AGAS

    AGAS

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    you need to put vaillant in your title so the vaillant guru's know to look at your problem who will give the best advice possible . they deal with vaillants everyday
     
  14. Teebob

    Teebob

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    Thanks. Title just changed
     
  15. Tipper

    Tipper

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    Have you checked the anti-cycling time?

    In my experience Vaillant seem to think ages is required on the pretext of better economy whilst ignoring the fact that the customer wants hot water...either for DHW or heating!
     
  16. Razor900

    Razor900

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    We could ask @Bunnyman for an answer but everyone in the top 100 knows he just waits for Agile to post then copies it :LOL::love::LOL:
     
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  17. Hason

    Hason

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    Hold up---- you say a combi but you have a y plan with zone valve,cylinder and tank.
    Also you set temp to 55 and it cuts out then that sounds to me like its doing its job,you need to up temp on heating to 66-70 oc then check operation
    Sounds like things dont add up
     
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