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Oso unvented cylinder mystery

Discussion in 'Plumbing and Central Heating' started by lostinthelight, 25 Mar 2019.

  1. lostinthelight

    lostinthelight

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    Well it is to me, but what have I missed
     
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  3. Dan Robinson

    Dan Robinson

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    The Immersun thing and the boiler are on the same fused spur.
     
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  4. Dan Robinson

    Dan Robinson

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    You've also missed a please and thank you.
     
  5. ianmcd

    ianmcd

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    it is not wired correctly as @Dan Robinson already told you, when you switched off the isolator for the immersun the zone valve from your boiler also closed it shouldnt
     
  6. lostinthelight

    lostinthelight

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    Sorry abour that but frustration got in the way of manners
     
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  7. lostinthelight

    lostinthelight

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    Id already tried that one by powering boiler from completely different circuit but its still the same
     
  8. lostinthelight

    lostinthelight

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    The wireing from the inersun goes to the immersion heater alone, there is no physical connection between the immersion heater and boiler ciruit
    Not only does the zv close but the boiler would have been firing if i hadnt of turned it off.
     
    Last edited: 25 Mar 2019
  9. Dan Robinson

    Dan Robinson

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    It's an interesting one... You'd need to trace the brown wire from the zone valve back through the cylinder stat and into the "wherever". The cylinder stat is picking up 230V from somewhere (it has a permanent live in it which can flummox some installers).

    Whilst possibly not a complicated fault to find, you need to know your way around a multimeter.

    Also - those cables are not secure in the wiring box of the cylinder - those little holes at the bottom should have clamps in them.
     
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  11. ianmcd

    ianmcd

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    when the Zone valve is open the manual fill lever has no resistance and feels like it is doing nothing, when it is closed the lever offers resistance when you try to move it, I heard it closing on your video , turn off the isolator again and check if you dont believe me
     
  12. lostinthelight

    lostinthelight

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    I think you have misread my reply as there is nowhere in there that disagrees with you, I was adding more info that the boiler would have also been firing had i had not turned it off.
     
  13. lostinthelight

    lostinthelight

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    Thanks for the info. I have gone part way to findind the problem but dont know why.
    The Uv cylinder system was fitted nearly a year ago and has been working perfectly except i have never used the immersion heater.
    Last week I had the solar switch fitted which brought the immersion heater into play and thats when I noticed the issue.
    I have now dissconected the solar from the immersion, connected it to the mains and everything is back to normal.
    I will have to get the solar Guys back to see what the issue is as powering the mains with solar has caused the problem
     
  14. MeldrewsMate

    MeldrewsMate

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    I wasn't clear from that video what your complaint is? If the fused spur for the iBoost (some called it Immersun) also feeds the heating system, then turning that off will undoubtedly cause the 'fault', however...
    If you read the small booklet provided with the iBoost you will see that a press of its 'boost' button will bring on the immersion heater for 15 minutes, bypassing the 'solar' function. Equally, the iBoost display will show you how much solar power is being diverted to the immersion heater, press the left button and it'll be revealed. If the display shows 'HOT', and the tank clearly is not hot, then check that the immersion heater overheat hasn't 'popped'.
    If the display shows 'OFF' and the sun is shining (and the kettle/washing machine/dryer/microwave isn't running) then check the current transformer on your incoming electrical system is both the correct way around, and is clipped closed. After that check the bluetooth pairing for sender and iBoost main box - see instructions.
     
  15. lostinthelight

    lostinthelight

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    Just an update on this which is still unresolved despite visits and tests by 3 solar electricians who have been in contact with the switch manufacturers. The only thing thats been established so far is the output voltage from the solar switch to immersion heater is DC but they are still unsure as to why the tank thermostat brings the boiler on when the SS is powering the IH despite there being no physical connection between them.
    The other thing is, if the overide mode on the SS is selected so the IH heater takes power from the grid instead of from solar which is using same circuitry, everything works as it should
     
    Last edited: 21 Feb 2020
  16. bernardgreen

    bernardgreen

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    Is this supply switched by any other devices ( thermostats, switches etc ) ?

    Almost all devices used in heating systems are designed for switching AC supplies.

    When switching OFF an AC supply the arc between the contacts will extinguish when the AC voltage goes through the zero crossing point ( when the current changes direction )

    When switching OFF a DC supply there is no zero crossing point and the arc will persist until the contacts have been separated far enough for the arc to break. This separation is more than the separation that occurs in switches designed for switching AC supplies.

    Equipment controlled by the switch can continue to have power through the arc, in other words the switch cannot turn OFF the supply

    Hence if standard ( 230 V AC ) switches are used to switch the DC then the immersion heater ( and maybe other items ) will continue to be energised.
     
    Last edited: 21 Feb 2020
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  17. lostinthelight

    lostinthelight

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    Sorry bernard I typed that inaccurately and will edit above to correct, the solar switch/immersun output to the IH is DC .
     
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