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  1. #27
    Join Date
    Apr 2010
    Location
    Minnesota
    Posts
    520
    Yeah that's all I've ever used too, I thought I read somewhere about some kind of inline refer measuring device. Maybe that's just a solenoid valve unit like the trane charge assist for the 16i units.

  2. #28
    Join Date
    Feb 2011
    Location
    BC, Canada
    Posts
    7
    All depends on the application.
    If I'm charging a rack for the frist time I'll just suck in 100lbs at a time, then weighing in the last bit. Always good to know how much you've put in. On a critically charged system you'll need to use a scale for sure, even a Dail-a-charge for small captube systems.

  3. #29
    Join Date
    Feb 2009
    Posts
    137
    Aside from the fact of charge accuracy would you buy coldcuts from a deli that guessed the weight. Been using a scale on cap tubes since the early sixties. bought my first digital in the early eighties.
    First digital scale was an Amprobe very accurate ate six or eight C batteries in less than an hour. Use a scale every time I charge a unit. Saves huge ammounts of time.

  4. #30
    Join Date
    May 2010
    Posts
    1,295
    I vacuum out the system and always replace filter drier when opening system with equivalent and typically always replace cap tube when I do open a system. Depending on the price of the equipment and age, when I find a burnout I typically suggest replacing it. Every small self contained system I have seen burnout has been 10+ years old. Owner has to weigh their costs. Is this unit going to be a problematic unit and cost me more money in the near future? Now blast chillers and high dollar self contained units I will repair.

    If a larger liquid line filter was placed in the unit I would determine the amount of refrigerant that the larger sized filter accommodated and subtract it from the original filters capacity and add the difference in refrigerant to the system.

    On small self-contained units do they make small suction line filters? Or do you just blow it out with nitrogen and try and get the most acid out as possible? I know you can get married to burnouts and typically on small refrigeration units (bar coolers, small reach ins, etc) like these burnouts aren't worth my time.

  5. #31
    Join Date
    Sep 2008
    Posts
    586
    So this isn't a troll

    I work almost exclusively on fractionals and always use a scale.

    While I can certainly can charge systems with a receiver to clear the sight glass + some extra you just can't qualify that extra particularly working with cold/hot refrigerant. When that box/product pulls down there is just to great a chance of being undercharged, on the flip side it could be easy to overfill the receiver and creating a situation of running high head pressure under heavy load and causing floodback.

    I also find it a necessity on the small systems particularly cap tube systems where the manufacturer does not provide operating pressures and the charge is small (<1#). I will often add a real filter/drier to these and can adjust the factory charge accordingly, anything else is just a guess.



    Do you use a micron gauge or is that another unnecessary item?

    The only time I don't use a scale is when using gas for leak testing or topping up a system with known leaks.

  6. #32
    Join Date
    Sep 2008
    Posts
    586
    oops dupe

  7. #33
    Join Date
    May 2010
    Posts
    1,295
    Ya, every tech I've had on site has not used a micron gauge. IDK wtf is their deal?

  8. #34
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    3,304
    Quote Originally Posted by ZeroTolerance View Post
    I know you can get married to burnouts and typically on small refrigeration units (bar coolers, small reach ins, etc) like these. Burnouts aren't worth my time.
    Amen to that. I have a call right now on an old prep table Im really dreading to fix.

  9. #35
    Join Date
    Mar 2007
    Location
    wedged in freezer shelf
    Posts
    7,067
    Since this was in the ice section
    in a small Manitowoc

    QM20
    4.6 oz (130 g) 134

    QM30
    5.8 oz (165 g) 134

    If you don't get the charge right they don't work right.
    Maybe they work when you are there but it will come back on ya without a scale as ambient temp changes. I doubt even the techs at the factory could get the charge right without something to measure the amount.
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  10. #36
    Join Date
    Jun 2006
    Posts
    1
    Been doing HVAC/R 43 years. Always replace cap tube when replacing compressor. Tripple evacuate using micron gauge and weigh in charge, to factory spec. Do it right the first time and save head aches later.

  11. #37
    Join Date
    May 2010
    Posts
    1,295
    Amen to that john, I do exactly the same thing; I install access fittings, new equivalent filter dryer and cap tube, purge with nitrogen, pull a triple vac, then fill with refrigerant by weight according to nameplate.. No need to do anything more like add a bigger filter drier on such a small system. Like I said, most of the time these smaller units aren't worth saving anyway.

  12. #38
    Join Date
    Jul 2005
    Location
    FLORIDA
    Posts
    1,163
    Quote Originally Posted by john l View Post
    Been doing HVAC/R 43 years. Always replace cap tube when replacing compressor. Tripple evacuate using micron gauge and weigh in charge, to factory spec. Do it right the first time and save head aches later.
    this should be gospel....


    I know a couple of fumbducks that try the touchy feely and add a little bit more then call and ask whats wrong or just condem systems.... these reach ins cost alot of money and can be fixed to run for another 15 years for half the cost of new ones

    watch one do the presure and temps and told the bartender that the compressor was going to have a short life expectancy and the owner question me about 4 months later brand new pump no cap tube change on system that was three years old no mainteance, condenser plugged 2 pumps later and warm beer and he won't call back lol "he's your friend"

    criticalcharge is the key word here and time to go back to basics
    once you think you've seen it all
    (THINK AGAIN)
    I would rather work for free than be look upon as a thief!!!!!

  13. #39
    Join Date
    Sep 2004
    Location
    graham washington
    Posts
    55
    always use scale when charging a captube system,ice machine,packgage unit......when system has a sight glass never, just weigh the tank after charging and then write with sharpie on tank the remaining amount, i do this to properly charge the customer for gas used on job.....................mfry curious as to why its time to learn not to??? been doing this for 28 years, and weighing in gas has never failed me yet......followed lots of "hacks" after their great skills were applied to machines and found lots of problems. most of them were one man shops!!

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