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No call for heat

Discussion in 'Plumbing and Central Heating' started by sadders, 27 Dec 2018.

  1. sadders

    sadders

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    The boiler is a Vaillant Ecotec plus 824. 3 years old and recently serviced. It’s in an S-plan system. Controlled by a controller for the HW and a nest 2nd gen for the heat. Kitchen tap and downstairs loo tap runs from the Combi and the rest of the house pumped from the tap.

    I’ve noticed over the last few weeks that the boiler only recognizes call for heat from the nest sometimes. Hot water is fine. Toggling the nest up and down sometimes solves it (radiator symbol on boiler then flame) sometimes not.

    Thought it may be the nest so have changed it for a hive. I’m a beekeeper so it fits :) I took the opportunity to rewire the wiring center as it was done a bit shoddily by whoever installed it. All fine for a few hours then same problem.

    I’m guessing now that the valve to the heating is knackered. Is this likely? Unfortunately I haven’t got a clue where it is. The cable to it just disappears into the wall. Can’t find where it is. I’m presuming it is the cable from the valve as it has 5 wires (L,N and E) and was wired in as a valve.

    I know I can’t open the boiler front because I can’t check the seal when closing and I know you can’t advise me on the internal wiring and connections because of this.

    Is there anything else I can check? Is there anywhere that the lost valve is likely to be so I can check it?

    With thanks and happy Xmas.
     
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  3. ianmcd

    ianmcd

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    unlikely to be inside the boiler anyway, read the manual about s codes on the boiler display and when your Hive is calling for heat check the s code and see what the boiler thinks is happening
     
  4. sadders

    sadders

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    I can’t see any codes.
     
  5. ianmcd

    ianmcd

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    That is why I told you to read the manual, you have to select them on the display, they dont come up automatically
     
  6. flameport

    flameport

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    On the flow pipe from the boiler.
    Perhaps near the boiler, or next to the hot water cylinder, or in a cupboard.
     
  7. sadders

    sadders

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    It says S30 - no call for heat.
     
  8. ianmcd

    ianmcd

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    Then you have an external control fault and its nothing to do with the boiler
     
  9. sadders

    sadders

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    Ok, so that’s good. Are there any common faults to look at first especially as it sometimes gets the call and sometimes doesn’t?
     
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  11. ianmcd

    ianmcd

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    as you have an S plan according to yourself not me , then I would be looking at the CH Zone valve first, when the stat and timer show a call for heating see if the valve has opened by trying to move the manual by pass lever if there is a resistance it hasent opened if there is no resistance it has opened but hasnt made the end switch to tell the boiler to come on
     
  12. ianmcd

    ianmcd

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    Reading your post again I think it is wired wrong, it sounds as if the boiler is receiving a call for heat from the HW controller then the heating is working but once the HW is satisfied both are going off, next time the CH doesnt come on turn the HW controller on and either run a HW tap for about 5-10 mins and see if that brings the heating on , if it does it is either the CH zone valve or it is wired wrong
     
  13. sadders

    sadders

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    I was just about to ask an additional question on the control valve. The cable from the control valve (at least I presume it is) has been extended. The colours I have to work with are earth, brown, blue, black and black and white. Not standard. Given that I cant find where the valve is, is there a way to tell which wire is which?

    Going to get it all checked later but the heating engineer I use and trust is off work until 7th of Jan and the house is chilly.
     
  14. ianmcd

    ianmcd

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    is the zone valve a 28mm zone valve ?
     
  15. snb

    snb

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    sounds more like a Y plan and the HW off is not wired in
     
  16. ianmcd

    ianmcd

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    valves are usually close to the HW cylinder take some pics and post them and we will tell you what you actually have it could be Y plan as already mentioned
     
  17. sadders

    sadders

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    Spot on. Good knowledge.
    Found the valve.
    Rewired and working fine.
    I think the valve still needs changing but I will get that done by a pro (hate draining the system etc).
    The family is warm now and can shower.
    @ianmcd thanks so much for your responses and advice.
     
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