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Oso unvented cylinder mystery

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

  1. JohnD

    JohnD

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    Really?

    How many incoming supply cables does it have?

    Don't you have an inverter?
     
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  3. lostinthelight

    lostinthelight

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    421F98F3-00B7-4EEB-A304-B227F82E31B2.jpeg F86F52A3-BA1C-4ED8-82CD-BC960F29BB10.jpeg
     
  4. JohnD

    JohnD

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    Judging by your pic, you have an inverter that converts the DC from your panels into AC

    Presumably it feeds the AC into your household circuits and the network.

    I can only see one supply cable into your iBoost, which presumably comes from your household circut.

    I therefore do not believe that your iBoost is capable of supplying DC to the immersion heater.
     
  5. bernardgreen

    bernardgreen

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    I assume you have found this page from the manufacturers Marlec

    LINK
     
  6. bernardgreen

    bernardgreen

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    I believe the principle is that a remote sensor measures the current at the meter and when the solar generation has spare capacity ( more than the network will or can accept ) the excess is routed to one or two heaters.

    The image has HTR1 and HTR2 and both are labelled + - which strongly suggests it is a DC supply to the heaters,
     
  7. SFK

    SFK

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    Bernard,
    I would agree that + - suggests that it is a DC supply to heaters as that is how I also read those labels.

    BUT, the manual, although it does not say DC or 240Vac, it does say Live, Neutral and 13Amps - all suggesting 240Vac.

    So my reading (feeling?) is that the diagrams suggest that the heaters (and so the outputs) are 240Vac:
    https://www.marlec.co.uk/wp-content...-iBoost-User-Manual-111215.pdf?v=6805cdfd0c7a

    Screenshot 2020-02-21 at 12.21.50.png

    Screenshot 2020-02-21 at 12.24.41.png
    sfk
     
    Last edited: 21 Feb 2020
  8. JohnD

    JohnD

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    it sends power to the heater when current generated exceeds current used in the house. i.e. when it detects current flowing down the meter tails instead of up (subject to a small de minimis).

    But the inverter changes the DC into AC before it goes into the meter and the house circuit or network. The FITS payment is calculated in proportion to the amount of AC sent into the house and network (the inverter and meter don't know where it goes)

    I see no cables carrying DC away from the inverter or into the iBoost. It only receives AC from the house circuit.
     
  9. JohnD

    JohnD

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    p.s.

    I've got one, but it was £220 down the drain.
     
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  11. bernardgreen

    bernardgreen

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    The system has a current sensor which is clipped onto the Live tails from the meter, this links by wireless to the "controller".

    Probably this means that if no current is coming into the house ( invertor supplying all the house needs ) then the immersion heater(s) are switched on by connecting to the house 230 V AC wiring.

    Maybe the fault is that the sensor is not talking reliably to the controller or has been incorrectly installed. ( wrong way round or on the Neutral tail )
     
  12. JohnD

    JohnD

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    No, only if current is actually being sent into the network.

    The device seeks to send enough current into the heater to use almost all the current that would otherwise go to the network. it seeks to limit the voltage sent to the heater so that the current is limited (it is only for resistive loads), and the heater does not draw enough to use power from the network.
     
  13. JohnD

    JohnD

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    I can send you mine to experiment with, if you try to mend it and return it within 3 months.
     
  14. lostinthelight

    lostinthelight

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  15. lostinthelight

    lostinthelight

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    Yes I have thanks, I had been in contact with them who suggest an option would be to fit the previous model which has AC output but I’m not that keen as it doesnt have a second output. pickup sensor is fitted correctly and the switch has been back replaced
     
  16. bernardgreen

    bernardgreen

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    Looking at the image of the immersion heater and the multimeter I cannot see a safety over temperature cut out. If the controller fails to the ON state there may be nothing to stop the immersion heater heating water continuously to the point of the tank seriously overheating /boiling.

    If the controller is rectifying the AC into DC then any safety cutout would have to be DC rated.
     
  17. JohnD

    JohnD

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    well that's interesting.

    so you have a model that takes in AC and rectifies it.
     
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