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Low Ambient Conditions

Eugene Silberstein 3
Eugene Silberstein 3 Member Posts: 1,380
in A-C, Heat Pumps & Refrigeration

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  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    Refrigeration and Year-Round Air Conditioning

    Although the heating season is upon us, there are many applications where the "chill heads" are still out and about, performing air conditioning and refrigeration service work on equipment that must operate properly year round. Of course, I am referring to heat pump systems, supermarket refrigeration, ice skating rink refrigeration, floral refrigeration and restaurant refrigeration, to name a few.

    There has been much discussion on the system-charging practices that are used during periods of low ambient temperatures.

    What methods have you guys been using and to what degree of success do you attribute to them, i.e. low call back rate, etc. ?



  • Empire_2
    Empire_2 Member Posts: 2,340
    Charging

    There are charts that take into consideration total additional length of liquid line and you can add or subtract accordingly. I have in the past blocked off cond fans and coils to try and simulate a 60 to 70* day, but when wind conditions are strong it screws it up.
  • Darin_3
    Darin_3 Member Posts: 27
    Bless you!!:)

    I have always wondered if there were reliable charging methods other than weighing it in. It always seems that when a charge is adjusted in low abient conditions, it messes with the units ability to cool efficiently in normal or warm weather. What a good question.
  • don_156
    don_156 Member Posts: 87
    That is a

    > I have always wondered if there were reliable

    > charging methods other than weighing it in. It

    > always seems that when a charge is adjusted in

    > low abient conditions, it messes with the units

    > ability to cool efficiently in normal or warm

    > weather. What a good question.



  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    As soon...

    As soon as we get some more feedback from some of the other guys, I'll provide some reliable low ambient charging methods.
  • don_156
    don_156 Member Posts: 87
    I just

    try and get my evaporator temps 15 degree below ambient.

    Also have try adding 126 degree above ambient at compressor
    discharge...R22 only.

    However no matter what I try I still tell the customer will see you come summer to adjust charge.

    I too look forward to hearing from others.









  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    How about...

    How about using an evaportor saturation temperature that is 35 degrees lower than the return air temperature? This will get you even closer.
  • don_156
    don_156 Member Posts: 87
    Thanks Professor

    Can that be used when charging heatpumps in heat mode?
  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    The 35

    The 35 degree delta-t was intended for cooling applications where the return air temperature is the room temperature. For example, if the room temperature is 75 degrees, the evaporator saturation temperature will be about 40 degrees, or 35 degrees lower than the return air temperature.

    More on heat pump charging to follow.
  • don_163
    don_163 Member Posts: 67
    Ok

    This is like pulling teeth...LOL.

    How about discharge superheat when charging heatpump or refrig equipment in low ambient temps.

    Would that be more precise and if not, why?
  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    Mom always told me

    that I should become a dentist. I think you just confirmed that, Don!

    Check this out... I think it will help you out for charging heat pump systems in the heating mode.
  • don_163
    don_163 Member Posts: 67
    LOL

    Moms know best.Thanks Professor I hope all is well with Mom by the way.

    So how the book going? Will it be availible any time soon?








  • Eugene Silberstein 3
    Eugene Silberstein 3 Member Posts: 1,380
    If you are referring to....

    If you are referring to my new book on pressure enthalpy, the answer is, "going very well and available soon". This is the first book that I am producing myself and I am very pround with its progress so far. I am hoping to have it completed by mid january.

    My goal with this book was to bring pressure-enthalpy, which was primarily used for system design, into the hands of service technicians. P-h is a valuable troubleshooting tool when used correctly.

    I will keep you all posted about the book's progress.

    As far as mom goes, she seems to be doing well considering the fact that she has very little kidney function. As you might remember, the doctors gave her three days to live on October 16th and, well, here we are on December 11th and she is still going... just like the Energizer bunny.

    Hope all is well with you, Don and thanks for asking about mom and the book.

    P.S. I know I asked you this before, but where in this fine land are you located?
  • don_163
    don_163 Member Posts: 67
    Yes Please

    someone step up to plate will ya!

    Professor, I'm in the tidewater area of Virginia.And please
    put us on the list when the book become availible.



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