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  1. #1
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    Daikin RZQ200 Defrost issue



    I have a RZQ200 on a OEM coil in an AHU which starts a defrost at an ambient of -5°C, Te at -11°C every 27 to 30 minutes but there's not a single drop of ice on the coil. The defrost then lasts >15 minutes and it takes then +/- 7 to 10 minutes before coil is hot enoiugh to start the fans.
    What triggers faulty the defost in this case? Charge is OK.
    We've taken IR-scan during the defrost and after 5 to 6 minutes, the whole coil still is at -1°C. I have pictures of it.


    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  2. #2
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    Re: Daikin RZQ200 Defrost issue

    Faulty coil thermistor, perhaps?

    Is your 4-way valve changing over correctly?

  3. #3
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    Re: Daikin RZQ200 Defrost issue

    Freeze protection function
    Start Te -1°C for 40 minutes
    accumulated
    OR
    Te A°C for 1 minute
    continuous
    (Indoor decision)
    Te -1°C for 40 minutes
    accumulated
    OR
    Te -3°C for 1 minute
    continuous
    (Outdoor decision)
    Te -1°C for 40 minutes
    accumulated
    OR
    Te A°C for 1 minute
    continuous
    (Outdoor decision)
    End Te > 7°C for 10 minutes
    continuously.
    (Indoor decision)
    Te > 7°C for 3 minutes
    continuously
    OR
    Te > 4°C for 20 minutes
    continuously
    (Outdoor decision)
    Te > 7°C for 3 minutes
    continuously
    OR
    Te > 4°C for 20 minutes
    continuously
    (Outdoor decision)

    Last edited by Peter_1; 26-01-2013 at 09:13 AM. Reason: Resized

  4. #4
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    Re: Daikin RZQ200 Defrost issue

    Thermistor was checked by Daikin itself and the 4 way is 100% working. It's the trigger for the defrost that botters me.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  5. #5
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    Re: Daikin RZQ200 Defrost issue

    I.M., what's Te ≤ A°C for 1 minute?
    As far as I can conclude now, there's no real detection if the coil is iced up at all. We can run under the present conditions at least 3 hours before we need a defrost. We're losing now a lot of energy and I'm wondering in how far this was considered in the overal COP of the machine!
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  6. #6
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    Re: Daikin RZQ200 Defrost issue

    Hi Peter I think A°C is the 'timer A'. In other words what ever the defrost interval settings are at.
    These can be changed by using 'mode 2' on the outdoor unit.
    The difference between genius and stupidity is that genius has its limits.

    Marc

  7. #7
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    Re: Daikin RZQ200 Defrost issue


  8. #8
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    Re: Daikin RZQ200 Defrost issue

    Quote Originally Posted by r.bartlett View Post
    Thanks Richard, I think I will need someone form Daikin to check and more specific to monitor while running at low ambients trying to analyze what triggers the un-needed defrost cycle wand why it last such a long time before we reach end defrost. There as too much variables to monitor finding out what's happening.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  9. #9
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    Re: Daikin RZQ200 Defrost issue

    Are you sure it's defrost and not oil recovery ?

  10. #10
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    Re: Daikin RZQ200 Defrost issue

    It's 100% for sure a defrost Richard (even Daikin followed once this machine) + sign on remote controller indicates defrost + 4 -way valve reverses and we took several IR-pictures while unit defrosted. Can post those. Takes a long time before defrost ends: 29 minutes running, shut down for a defrost and then +/- 22 to 24 minutes before units blows heat again. Not that good for the SCOP or SEER I presume.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  11. #11
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    Re: Daikin RZQ200 Defrost issue

    Most defrosts are a version of the old

    instigate defrost
    Time+ temperature

    Terminate defrost
    Time or temperature

    If this isn't happening it's most likely the board...Rough part changers guess but from where I am sitting it's my best shot :-)

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