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Suction/liquid heat interchanger

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Techman
Techman Member Posts: 2,144
in A-C, Heat Pumps & Refrigeration
We recently started working for a new A.C. customer,the liquid line was in full contact with the suction line ,from the cond unit all the way to the evap coil(40'-45')and both lines were wrapped by Armaflex insulation.Why?Does anyone know of a benefit to this practice? Maybe ,saving the cost of insulating the liquid line as well? The attic is very hot!And attic venilation will be in their future,very soon!

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  • bob_50
    bob_50 Member Posts: 306
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    It

    subcools the liquid which increases refrigerating effect in the evaporator and superheats the vapor in the suction line which reduces compressor capacity. Kind of six of one half a dozen of another. There was a time when manufacturers used to require us to solder the liquid line to the suction line. Suction liquid heat exchangers are still manufactured I believe.
  • Techman
    Techman Member Posts: 2,144
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    Bob

    Good morning,Which mfrg of AC says that? Just being curious! Walk-in freezers require a S/L heat exchanger which is about 18"long,and cap tubes systems are most times soldered to the suction line,but on AC systems I'm not familuar with that practice.Thanks!!
  • Empire_2
    Empire_2 Member Posts: 2,343
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    Good Morning Terry

    If you look at you P&E charts additional sub-Cooling of the liquid line increases the net Ref. Effect.

    Mike T.
  • bob_50
    bob_50 Member Posts: 306
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    Tech

    To be honest I can't remember. I'm talking late 50's. The practice was not unusual. It might have been Mueller or Westinghouse.
  • bob_50
    bob_50 Member Posts: 306
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    Mike

    What you say is true IF the heat removed in subcooling is rejected from the system. With suction, liquid, exchange the heat stays in the system.
  • Techman
    Techman Member Posts: 2,144
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    wHICH WAY TO GO?

    Thanks Bob! Hi Mike T! Its been months and months since the last time I was able to sit and be here ,amoungth's[?] all of you! Mike ,I think of you and your Dad ,quiet often ! I trust he and you are doing great! Happy "Fathers Day" to you ,both!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Ditto to you, Professor!Professor,what is the "braineact"side of this?
  • don_185
    don_185 Member Posts: 312
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    If

    your metering device is in the outdoor unit then the liquid line becomes part of the evaporator.Its no longer a liquid line.
    If not...................
    I would think by wraping the two together for that long of a run you will lower your superheat maybe low enough to harm the compressor.

    On the other side you will lose your colum of liquid one needs for proper valve operation.



  • bob_50
    bob_50 Member Posts: 306
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    Don

    isn't the liquid line usually warmer than the suction line? Heat flows from hot to cold. Wouldn't that tend to warm the suction line and increase the superheat and further subcool the liquid?
  • don_185
    don_185 Member Posts: 312
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    lol

    You got me.I was wondering if anyone was paying attention.

    So why would we want to increase the system superheat?
    How can added heat to the suction line be of any benefit?

    Other then reducing flash gas in the liquid line which I could see no reason why there will be any worry of that in a hightemp system.What purpose could it serve?




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