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Is it true?

What is the tonnage? What Refrigerant? TXV or restrictor? Although it may have to do with the velocity in the LL, but I find it hard to believe that it would make that much difference... There are other factors at work here which I wish you had seen first hand. If it's 2 ton it should be 3/8" LL. 1.5 ton can use 5/16". That sounds like a drastic move, Replacing the LL when other factors weren't divulged.

Mike T.

Comments

  • Techman
    Techman Member Posts: 2,144
    Is IT True?

    Hi! On a residential split system ,the system was not comforting the house properly,the liquid line was properly downsized from 3/8 to 5/16 , and everone was happy!How/Why? I was told this story!thanks!
  • Techman
    Techman Member Posts: 2,144
    Liquid line

    Hi Mike!R=22 ,all other factors unknown .Enjoy!
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    hmmm

    Was the refrigerant recovered and replaced along with the liquid line?

    Something to ponder, especially if the system contained noncondesnables....
  • Techman
    Techman Member Posts: 2,144
    Is IT ?

    Morning! So an oversized liquid line does not cause a problem?thanks!
  • Empire_2
    Empire_2 Member Posts: 2,343
    Possibly...

    Depending on the tonnage of the equipment. 2 ton is 3/8" LL at about 100ft/per min velocity. 5/16" would increase that velocity, but should not effect it that much. Now 1/2" LL line,...not to say that was it, but the velocity would drop well below the recommended 100ft/per min. Now you would have problems.

    Mike T.
  • jim lockard
    jim lockard Member Posts: 1,059
    LL size

    I know what they say Rheem likes 5/16" LL, Goodman and most others like 3/8" the GE Tranes used 1/4". Would it not be great to replace the line set when you changed the system? In the real world that can not happen. Over the years we (all of us) have connected A/C and H/P units to the existing line sets and Suprize we make the systems work.(IMHO) Best Wishes J.Lockard
  • Empire_2
    Empire_2 Member Posts: 2,343
    I hear you Jim...

    I cannot think that changing the LL for this unit would make an Super Duper difference. ;-) That's the only reason I dived into the Engineering manuals to get a why or why not, and I really could not find one. I guess anything is possible, but like all of us we want to know why!!!....

    My .02

    Mike T.
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    True Mike...

    If the system is operating with a fixed bore metering device, the change between a 3/8 and a 5/16 inch liquid line will not likely have a drastic effect on system performance. Fixed bore metering devices allow flow through them depending on the size of the tube, the bore of the tube and the pressure difference across the tube.

    The first two of the three items are inherent in the system at the time of manufacture and the field installer has nothing to do with them.

    Although it seems that there is not much of a difference between a 3/8 inch and a 5/16 inch liquid line, the fact is that the cross sectional internal area of the 3/8 inch tube is nearly twice that of the 5/16 inch line.

    Assuming that the system was recharged to the same pressures after the line change was made, the capillary tube will not know the difference between the 3/8 line and the 5/16 line.

  • Empire_2
    Empire_2 Member Posts: 2,343
    All due respect Gene....

    The area of the tube is set and I don't have a problem with that. It's the rated flow at a given tube size. That is fact... ( if I can get this darn scanner to work I will send info). The area in the 3/8" is almost if fact, Nearly twice that of 5/16" in your words, which I believe.....;-). But what is the Affected result of this area change? or it's behavior as i like to call it. Not much if you are 2 tons and under.... LL aprox. velocity for some not all Ref, is aprox 100-150ft/min. We have all used 3/8" LL for 5 ton also and that's where I am q: the change of the LL on this origional Question.

    I may be thinking this out to hard, but like I said...I find it hard to believe that a change is the LL made Mr & Mrs. Jones Happy...;-)

    Mike T.
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    I totally agree Mike

    My point is that, given that the metering device is likely a fixed bore device, the change in LL size would NOT have a major effect on what the customer experiences as far as cooling goes.

    My earlier post mentions that, more likely than not, something else was done during the process of changing out the liquid line.

    These may include removing and replacing the refrigerant or replacing a clogged LL filter drier.

    So There!

    :)
  • RadPro
    RadPro Member Posts: 90
    What if?

    Hi all

    What if the system was sized for 5/16 and charge was not added for the 3/8, you potentially have an undercharged system. That would make it work when you went back to 5/16. I agree that it shouldn't make a lot of difference but then again it might.

    Also, york and other manufactures where using 5/16 into the 1990's, it was cheaper to buy 3/8 line sets instead of seperate cheaper 5/16 lines. Even on systems larger than 2 tons.

    Don in MO
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