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  1. #1
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    Jan 2009
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    R407C Superheat, subcool.



    Hi all.
    I'm probably going to shoot myself in both feet for asking this question - what is the expected SH and SC figures for R407C, please? (in *C)
    If I'm right, the SH for R407C should be in the order of 6 to 8C*, but SC?
    I have tried an internet search, but seem to bang my head against several brick walls - or is it that the walls are banging at my head?
    There is a lot if info for R22 etc, but so much of it is in *F.
    The reason for the question relates to a swimming pool heat pump.
    There is no discharge service valve, but a schraeder valve just before the drier.
    Suction Press 4.8 bar
    Liquid Line Press 21.5 bar
    Suction Temp 15*C
    Discharge Temp 46*C (the most consistent, very difficult access)
    Liquid Line Temp 27*C
    Evap Air On 21.4*C
    Evap Air Off 17.8*C
    Pool Water In 24*C
    Pool Water Out 27*C

    I had to remove front cover to get these figures, and let the machine settle for at least 10 mins, after refitting front panel (affects evap air flow).

    From this, I reckon SH to be 7.8C*, and SC to be -24.7C*?
    I'm aware there are other variables to be collected, water flow volume etc., but this was a snapshot info collection because the evaporator was heavily iced the day previously (ambient in excess of 20*C).
    Any help would be appreciated
    Many thanks for sticking with the rambling!
    Graham


    en boca cerrada no entran moscas

  2. #2
    Join Date
    Mar 2006
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    Re: R407C Superheat, subcool.

    Liquid line pressure 21.5 bar (gauge) corresponds to 51°C saturated temp.
    The subcooling in your case is 51-liquid line temp 27°C = 24K

    Generally speaking SH and SC have no fixed figures.
    I would suggest a min SH greater than the glide of R407c and smaller than 12K.
    And I would suggest a SC at least 2K greater than the corresponding depression of the saturated temperature caused by the pressure drop of the liquid line.

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