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Are my 2-Port Valve wired incorrectly? Kettling problem.

Discussion in 'Plumbing and Central Heating' started by BoutTime, 20 Mar 2021.

  1. BoutTime

    BoutTime

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    It only happens with CH off. Also downstream of the pump and into the bypass it gets ridiculously hot. It's too hot to touch both sides of the pump. But only with CH off.
     
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  3. dilalio

    dilalio

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    Wired like you have it, there's the chance that MZV(s) is/are fully/partially closed/stuck and boiler is still firing as the microswitch has been bypassed.
     
  4. BoutTime

    BoutTime

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    It's possible this may have been the case in the past. Both valves closed and the pump may have been running along with the boiler.

    But today I checked and the pump and boiler were off.

    With the cylinder stat set at 60 there shouldn't be enough heat build up to cause kettling surely. I understand that the static water even with the boiler off can rise in temp but surely not that much?

    Cylinder stat is positioned half way up cylinder so I would expect the water to be hotter than its set at the outlet at the too. But the kettling is before the HW zone valve.
     
  5. fixitflav

    fixitflav

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    You'd expect it to be worse on HW only, as there's less heat dissipation. But it's not a major job to check the pump to eliminate it as the culprit.
    To add to what dilalio said - the boiler and pump should only be powered via the microswitches, to confirm at least one of the valves is fully open.
    Does the HW cylinder get hot? If so that valve can't be completely closed.
     
  6. dilalio

    dilalio

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    Kettling is always due to heat not getting away from the boiler either through poor circulation or dead-head firing which should not occur with appropriate interlocks.
     
  7. BoutTime

    BoutTime

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    The cylinder does get hot but the outlet at the bottom cools right down once HW switched off indicating the valve is closed. The valve turns freely by hand and it's a new Actuator.
     
  8. fixitflav

    fixitflav

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    That has nothing to do with it. The cylinder stat only stops the boiler when the 60° is reached. If the flow is too low kettling can start before that point.
     
  9. BoutTime

    BoutTime

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    I'm boosting the HW now with the CH off. Will see what happens.
     
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  11. BoutTime

    BoutTime

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    Whats interesting is I had to wind the cylinder stat up from 55 to get the HW to come on as the water in the cylinder was past 65.
     
  12. BoutTime

    BoutTime

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    OK so the kettling occurs when the HW is still on (valve open, pump on medium setting and boiler fired up). Below is a short video where you can hear the kettling. You will see me check the pump and then decrease the cylinder stat to turn the HW off. The Valve closes and I then check the pump isn't running by trying to select the higher speed. The boiler turns off and the kettling gradually dissipates.

    https://photos.app.goo.gl/eVceeGu1C3MGs2sV7

    I've just tried it again but had to turn the boiler stat up to max to get it to fire. I also ran the pump on high in case that dissipated the heat better. Still making awful noises. Possibly it is the pump but it's bizarre as the CH circulates well enough with no noise from the pump. Now the Valve Actuator has been replaced I'm going to try running the boiler and HW Cylinder Stat a little lower and see how it goes. Thanks to everyone for your input. Much appreciated. I'll feed back with any findings. Cheers.
     
  13. ianmcd

    ianmcd

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    Couldnt really see the very top of the cupboard, is that an air seperator fitted up there ?
     
  14. BoutTime

    BoutTime

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    I believe so yes. It's where it seems to eventually dissipate.

    upload_2021-3-20_19-44-9.png
     
  15. BoutTime

    BoutTime

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    I think you might be onto something @ianmcd .

    Just doing a crash course now...

     
  16. BoutTime

    BoutTime

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    So is it possible the root of my problems here could be that I have a common feed and expansion pipe? I've just been up in my loft as I'd wondered previously when bunging the system to change some radiator valves why there was no expansion pipe.

    The water up there is still steaming hot inside the plastic tank. I'm obviously just a DIYer here but for me, having an air separator 'venting' into a pipe that is constantly filled with water is not a wise thing to do.
     
  17. DP

    DP

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    If you do not follow what I am saying, draw the S Plan schematic and then try and reason what I write

    HW zone being active will maintain CH valve open when that Chanel power has been removed by the programmer :whistle::whistle:
     
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