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  1. #53
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    Oct 2016
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    Quote Originally Posted by VTP99 View Post
    The receiver is not just for a change in load. It's a necessary component with a pump down system. Also the particular placement of the LLSV, size and length of liquid line. All that determines the size of a receiver.
    Sure, I could see that. but in terms of performance, looking at how a system operates and if it's operating correctly, the SG only tells you so much and just because it's not full doesn't mean the system can't perform properly.

    A fridge is not a blast chiller, it's meant to maintain product temp below 39*F not cool it down from 150*F, at least that's what I was told, yet the chefs will try to do it occasionally, I would put a receiver in a system just to have it be a pump down system, that's a good enough reason for me.

    But here's what I don't like, pretty much what I got when I started was, before you do ANYTHING you look at the SG, if it's not full, you start with that. But what if a system has been running fine for a year, showing 1/2 full SG, then you show up and say OH! It must be a leak, the SG is not full, it's lost refrigerant.

    Then you jump right into trying to find it, When it was just a TXV powerhead gone bad or whatever it may be, but the idea that the SG has to be full was to beaten into your head that you couldn't proceed without the SG being full.

    It's tripped me up before, making me believe a system had a leak because the SG was not full, making me spend time I didn't need to on a problem that didn't exist. That's why I'm trying to clear it up.

    Hyperfusion,

    I wouldn't be able to say, I've seen what I've seen and what I believe is what I believe, I could very well be wrong in this, that's why I'm asking these fellas, so don't make any conclusions just yet. I used to think a SG had to be full or the system was dead in my eyes, after having done the work and seen different things, It seemed to not be the case and a system can perform just fine without that extra amount of refrigerant in the receiver, but it would depend on the load, that's what I was missing before.

    Might be fine when you are looking at it, throw another 60*F in the box and it might not be.

  2. #54
    Join Date
    May 2014
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    Bay Area California
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    This is what we are trying to tell you about a "rivering" sight glass.

    A half full sight glass is not the same thing as bubbles or foam.


    Quote Originally Posted by Olivero View Post
    Sure, I could see that. but in terms of performance, looking at how a system operates and if it's operating correctly, the SG only tells you so much and just because it's not full doesn't mean the system can't perform properly.

    A fridge is not a blast chiller, it's meant to maintain product temp below 39*F not cool it down from 150*F, at least that's what I was told, yet the chefs will try to do it occasionally, I would put a receiver in a system just to have it be a pump down system, that's a good enough reason for me.

    But here's what I don't like, pretty much what I got when I started was, before you do ANYTHING you look at the SG, if it's not full, you start with that. But what if a system has been running fine for a year, showing 1/2 full SG, then you show up and say OH! It must be a leak, the SG is not full, it's lost refrigerant.

    Then you jump right into trying to find it, When it was just a TXV powerhead gone bad or whatever it may be, but the idea that the SG has to be full was to beaten into your head that you couldn't proceed without the SG being full.

    It's tripped me up before, making me believe a system had a leak because the SG was not full, making me spend time I didn't need to on a problem that didn't exist. That's why I'm trying to clear it up.

    Hyperfusion,

    I wouldn't be able to say, I've seen what I've seen and what I believe is what I believe, I could very well be wrong in this, that's why I'm asking these fellas, so don't make any conclusions just yet. I used to think a SG had to be full or the system was dead in my eyes, after having done the work and seen different things, It seemed to not be the case and a system can perform just fine without that extra amount of refrigerant in the receiver, but it would depend on the load, that's what I was missing before.

    Might be fine when you are looking at it, throw another 60*F in the box and it might not be.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

  3. #55
    Join Date
    Jan 2010
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    Here's a different example.
    We understand that small self contained cap tube systems are "critically charged". So if a 12oz. system is say 4oz. low one might think it won't work.
    WRONG it will work ( I've seen them shorter on charge and work) it just takes longer for it to reach temperature settings.
    So YES even though it's working it's not working efficiently.

  4. #56
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    Mar 2015
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    Quote Originally Posted by VTP99 View Post
    Here's a different example.
    We understand that small self contained cap tube systems are "critically charged". So if a 12oz. system is say 4oz. low one might think it won't work.
    WRONG it will work ( I've seen them shorter on charge and work) it just takes longer for it to reach temperature settings.
    So YES even though it's working it's not working efficiently.
    Hos 4:6 My people are destroyed for lack of knowledge. Because you have rejected knowledge, I will also reject you, that you may be no priest to me. Because you have forgotten your God’s law, I will also forget your children.


    "You've got to Stand for Something or You'll fall for anything" (A. Tippin)


    Mat_15:24 But he answered, “I wasn’t sent to anyone but the lost sheep of the house of Israel.”

  5. #57
    Join Date
    May 2014
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    But it's drawing less amps when it is running, so it's saving me money.




    Quote Originally Posted by VTP99 View Post
    Here's a different example.
    We understand that small self contained cap tube systems are "critically charged". So if a 12oz. system is say 4oz. low one might think it won't work.
    WRONG it will work ( I've seen them shorter on charge and work) it just takes longer for it to reach temperature settings.
    So YES even though it's working it's not working efficiently.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

  6. #58
    Join Date
    Jul 2000
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    Guayaquil, EC
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    In my experience the sightglass will indicate low charge pretty consistently if there is any sort of turbulence in the glass. If the flow is relatively smooth then the charge is not low. If there's a steady stream of bubbles flowing through, as is often the case the 400 series blends, the SG would still indicate to me the charge is not low.

  7. #59
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    May 2014
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    Yeah, Icor had trouble with techs not following charging instructions with their first Hot Shot.


    Quote Originally Posted by icemeister View Post
    In my experience the sightglass will indicate low charge pretty consistently if there is any sort of turbulence in the glass. If the flow is relatively smooth then the charge is not low. If there's a steady stream of bubbles flowing through, as is often the case the 400 series blends, the SG would still indicate to me the charge is not low.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

  8. #60
    Join Date
    Oct 2016
    Location
    Clearwater, Florida
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    Okay, I see what you are saying.

    So as long as the SG is not turbulent or foamy, it could very well be fine.

    I'm not saying that a half full SG will run it inefficiently, that's not what I've seen, or perhaps I am wording it wrong, during NORMAL operation the system is running perfectly fine, if there was any loss in efficiency I would be seeing it on the evap SH or the comp SH would be higher than usual.

    I guess you might get tripped up on a heavy load but during regular, normal operation, the system can run just fine with the SG half full.

    If it was half full and turbulent, foamy or bubbly it could indicate a low charge.

  9. #61
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    Aug 2002
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    Southold, NY
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    Remember the key term is “A solid colum” of Liquid.

    Excessive head pressure will cause bubbles as well. The SG is only 1 Tool in the arsenal !

  10. #62
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    And to throw into the mix, you could have a full SG and still end up without a full column of liquid at the TEV.

  11. #63
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    Jan 2019
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    Quote Originally Posted by HyperFusionHVAC View Post
    So I’m a residential and commercial air conditioning tech who’s starting to work on commercial and residential refrigeration systems and I’m really only familiar with how to charge a system based on the super heat and sub cooling methods. I know on a residential AC condenser it will list the desired sub cooling that the manufacturer recommends so I usually charge to that when there’s a TXV but when it comes to a fixed orifice on a residential system or a capillary tube on a commercial walk in/reach in or even a txv on a commercial walk in reach in I can’t even seem to find a specification on what the superheat or sub cooling should be. How exactly do you guys who are refrigeration seasoned pros know how to check the charge on a refrigeration system or how to charge it properly if there is no rates super heat or sub cooling on the specs?


    Sent from my iPhone using Tapatalk
    Been doing refrigeration for 3 years honestly best way to charge refrigeration is off a sight glass lol.. shifty buys it’s been good so far



    Sent from my iPhone using Tapatalk

  12. #64
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    Jun 2011
    Location
    NE Ohio
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    Ice explained it well one day .... the charging ' sweet spot '

    charging a system with a receiver, TXV, sightglass, non blend

    using a sightglass will get you started, however ......

    adjust your charge by subcooling .... slowly add refrigerant .... your subcooling should go from zero, to something, say 5 degrees, if you are adding refrigerant and your subcooling is no longer increasing then STOP, you are pretty much at the ' sweet spot ' ... probably the best way to charge a system as far as I would think ...... still haven't tried it yet, haven't had a chance to, but I feel pretty confident that is the best way

    since we are discussing charging a system may as well explain how to do it properly, not half full, not rivering, no bubbles

    technically, you should probably measure your pressure AND your subcooling just before the TXV, technically ... just the same your suction pressure should be measured at the evaporator outlet when adjusting your superheat ..
    "All that is necessary for the triumph of evil is that good men do nothing." (Edmund Burke)

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