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Vailliant eco TEC plus 430 Heating up when no call

Discussion in 'Plumbing and Central Heating' started by leshill1, 29 Sep 2021.

  1. leshill1

    leshill1

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    I have a Vailiant 430 and today for the first time I turned the heating on due to it being cold. I found that after a while the heating was remaining on despite the Nest having been switched off. I went to the boiler and found the radiator symbol flashing which I understand means its active. I set the default base temperature on heating down to 65 and sure enough, it went off and the temperature dropped at the boiler. Once the lower temperature was reached the boiler kicked back in again. I reset the boiler by way of a full power cycle but still, it fired up. I removed the Nest from the cradle and re-plugged it back in and things now seem to be OK.

    I'm thinking the Nest unit must have been stuck on despite saying it was off, anybody any idea?
     
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  3. picasso

    picasso

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    More likely to be the heating 2 port valve stuck, it probably freed its self but will stick again at some point.
     
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  4. leshill1

    leshill1

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    ok, so here's the thing. If neither the water or the heating was making a call for heat i would have thought that the 2 port value would not come into play here. Today I inspected the 2-port value and when i make the call for heat it moves over to the Heat position but when i stop the call for heat it does not move back to the water position, it stays on heat. If i shut the power of to the Nest controller that feeds the port value then the slider moves back to the default position. The value itself with the valve motor clicked off moves freely between both positions. If i examine the motor value and call for heat i can see the value insert move to the heat position but when i remove the call for heat it does not move back which would imply the mechanical port of the 2-port value is not at issue here. I notice on the boiler the tap symbol is lit but is not flashing, does that mean hot water is actually being called here although it's at a temperature so not flashing? Had that been the case I would have expected the 2-port value to be at the Water position and then when heat is called to move to center position for both water and heat.
     
  5. ianmcd

    ianmcd

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    you are confused 2 port valves do not have a water position, do you mean a 3 port valve ? post pics of what you have
     
  6. leshill1

    leshill1

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    Yes sorry, 3-port value is correct.
     
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  8. leshill1

    leshill1

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  9. ianmcd

    ianmcd

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    when you remove the call for heat the valve will stay in the heating position until a call for HW is made
     
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  10. leshill1

    leshill1

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    Thanks Ian, it looks to be working fine for now then. Call for Heat only and it moves to H position, call for water only and it moves to W, call for both moves to mid-position which now makes sense. What i didn't expect was that it remains at last position when all calls for heat are removed but thinking about it makes sense. There is also an overun that means even when call for heat stops the pump still goes to move heat away from the boiler exchange to save damage.
     
  11. ianmcd

    ianmcd

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    yes thats all perfectly normal
     
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