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Thread: Charge question

  1. #1
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    Charge question



    Hello everyone

    I have just recharge my split ac system due to a leak. I have also move the outdoor unit and put on longer lines. So a have recharge with the superheat methode, wich is about 5-6C now. I think this is ok.
    When measuring the temp of the indoor unit it is now 23C inn and 4C out witch is a diff of 19C is this to high of a difference? when winter will com and i turn it over to heating will this still be oK?

    Regards
    Morten



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    Re: Charge question

    How long are those refrigeration lines. Before and after? And what model is your a/c split?

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    Re: Charge question

    As a trained engineer working on AC you'll be aware that splits will come pre-charged amount of refrigerant for x amount of pipework

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    Re: Charge question

    Yes i know that
    .
    But it was running for a year or so with a minimal leak.
    Until the liquid line and the evaporator started freezing up.
    Then i where going to have some renovations done on the house.
    So i did a pump down on the remaining r410 in the system and unmounted the complete outdoor unit.

    Now the renovations is done and the outdoor unit i mounted i little bit further away.
    Witch makes the distant about 2M longer, and i also had to compensate for longer lines and previous leakage.
    So that is way i did charge the superheat way.

    The unit was precharged for 5M now they are about 7M, witch according to the label of the condenser i should add 20g/M (total 40g + what ever is lost in the previous leak.)

    This i a cheap "China" on/off AC/heat pump model called "Invest"

    Reg
    Morten

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    Re: Charge question

    Did you recover that old R-410A and did you scale it? How much is missing?

    In my opinion, that outcoming air is too low. What are the pressures and outside temperature?

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    Re: Charge question

    No i don`t have recovery equipment. so i just pumped the remaining refrigeration in to the condenser.

    I only have service valve on low side suction line.

    The pressures there are:

    AC off = 14Bar (203Psi)
    AC on and running for some minutes it is about 6.68Bar (97Psi)

    Outside temp about 18 - 20C (64 -68F) HM 75%-85%

    Thanks for your answers.

    Reg
    Morten

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    Re: Charge question

    buy the way i also measured the current of the compressor... it is rated to 4.7amp in cooling mode.

    i have under "full load" (coldest setting) 4.0 to 4.1amp

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    Re: Charge question

    Quote Originally Posted by jdunc2301 View Post
    As a trained engineer working on AC you'll be aware that splits will come pre-charged amount of refrigerant for x amount of pipework
    As a trained engineer working on a/c you will know that a system with x amount of gas pre charged for x amount of pipe work goes out the window when you have a leak.

    But to the OP your evaporating pressure is a bit low for 410a with that air on temp..
    Cheers
    Stu
    Tool's ? check ! Condom's ? check !
    If you can't fix it , f*ck it !!!

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    Re: Charge question

    Yes some but not all was gone out the window. sins it was still "working" then I pumped down the rest to outdoor unit. Aldo the proportions of the R410a mix may not be correct after leakage?

    by the way leak was fixed when pipe lines was changed.

    How come the performance seems so good with 19C difference between air going in / out of the evaporator?

    low pressure still an indication of under charge?

    What will be the symptoms if I theoretically overcharge the system?

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    Re: Charge question

    Quote Originally Posted by stufus View Post
    As a trained engineer working on a/c you will know that a system with x amount of gas pre charged for x amount of pipe work goes out the window when you have a leak.

    But to the OP your evaporating pressure is a bit low for 410a with that air on temp..
    Cheers
    Stu
    It leaks, recover the whole lot N2 p/test find leak, fix leak,vac, recharge to plate...add charge as stated above.. If you haven't got a recovery machine then your playing in the wrong trade....might aswell just vent the whole lot and start from fresh..all seems simple to me...especially on a small split

    not that i agree with venting, and i dont do it...(before anyone has a pop)

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    Re: Charge question

    Quote Originally Posted by mortenm82 View Post
    Yes some but not all was gone out the window. sins it was still "working" then I pumped down the rest to outdoor unit. Aldo the proportions of the R410a mix may not be correct after leakage?

    by the way leak was fixed when pipe lines was changed.

    How come the performance seems so good with 19C difference between air going in / out of the evaporator?

    low pressure still an indication of under charge?

    What will be the symptoms if I theoretically overcharge the system?
    Here goes!
    Overcharged…
    1) Excessive subcooling at condenser outlet.
    2) Tripped on High Pressure Cut-out.
    3) High suction pressure with Low Suction Superheat.
    4) High delivery gauge reading with Normal superheat readings
    5) Low Delivery Gauge reading with low superheat
    6) Power absorbed by Compressor High

    Undercharged…
    1) Cut-out on L.P.
    2) Low Suction Pressure with High Suction superheat
    3) Low Discharge Pressure with High superheat
    4) Power absorbed by Compressor Low
    5) Comp shut down on L.P.

    The above is a guideline and not an complete list!
    Good Luck Grizzly

    Courtesy of Grizzly previous post

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    Re: Charge question

    Quote Originally Posted by jdunc2301 View Post
    Here goes!
    Overcharged…
    1) Excessive subcooling at condenser outlet.
    2) Tripped on High Pressure Cut-out.
    3) High suction pressure with Low Suction Superheat.
    4) High delivery gauge reading with Normal superheat readings
    5) Low Delivery Gauge reading with low superheat
    6) Power absorbed by Compressor High

    Undercharged…
    1) Cut-out on L.P.
    2) Low Suction Pressure with High Suction superheat
    3) Low Discharge Pressure with High superheat
    4) Power absorbed by Compressor Low
    5) Comp shut down on L.P.

    The above is a guideline and not an complete list!
    Good Luck Grizzly

    Courtesy of Grizzly previous post
    Thanks a lot.

    from all this info i think my ac a little bit under charged...

    Reg
    Morten

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    Re: Charge question

    Recover all refrigerant and make a fresh start. And remember, that R-410A is not a one component refrigerant and it is leaking out... So it would be better if you charge your split with a new R-410A.

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