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    Its been getting cold out (11 Posts)

  • Probie Probie @ 7:15 PM
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    Its been getting cold out

    Hey everyone I'm a new guy to the trade (2 months in) and live in the northern regain of the us. I was wondering when it gets this cold out how can you charge a refrigeration unit or Air conditioning unit that has to be running all year round and is outside in the low ambient conditions?
    This post was edited by an admin on December 19, 2013 7:15 PM.
  • Spence Spence @ 1:36 PM
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    Low Ambient Charging

    The ONLY way is to weigh in the charge. For example, the outdoor section of a residential split system is stamped 6 lbs./5oz. of refrigerant. This means that exact amount is adequate for the outdoor coil, the smallest AHRI rated indoor coil for that unit, and 15' of tubing. If you have a larger coil or longer tube set you need to add "x" additional refrigerant. The additional charge amount is found in the IOM manual or make a call to the distributor's technical department for help. If you do the proper weigh-in, provided your air flow is within factory tolerances, you will be close enough to not have to worry about the unit's performance. When the ambient rises to a temperature that allows customary charging, use the chart inside the OD unit for proper temperatures and pressures. And, as always, check your air flow, superheat, and sub cooling.
  • Probie Probie @ 6:26 PM
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    ONLY way…?

    i have read in the modern air conditioning and refrigeration book about weighing in the charge as you have explained, but my step father is in the business and i asked him he said he turns the condenser fan off to raise the C.T. to 95 degrees so you can charge properly. i have also asked other people outside of heating help and they have also told me other ways to raise the C.T. so you don't have to always weigh in the charge. ex: putting cardboard on the sides of the condenser or a tarp. i have also seen in a fieldpeice brochure what they call a charging jacket (in the low ambient charging section) and that goes over the top of the condenser and keeps the same air circulating in the condenser to raise the temp to 95 degrees or so. I appreciate the info on just another way to charge during the winter, but as for there being only ONE way i have to say that i disagree with that.
    That is the link to the fieldpiece page for the charging jacket i think its a really cool new item to help all mechanics in the trade charge during low ambient temperatures!
    This post was edited by an admin on December 21, 2013 6:31 PM.
  • Techman Techman @ 10:12 AM
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    charging AC units

    Merry Christmas to ALL!  This AC charging subject, in every kind of weather conditions, has come up several times. While I do agree w/ Spence that the weight charging method has its advantages , I disagree that the weight charging way is the only way. There are several ways of charging a system, properly!
    If the refrigerant charge is stamped on the unit nameplate and that charge is rated for 15' , then does the SubCooling rating that is also on some nameplate's also derive from that same 15' of line set? Welcome to the trade Probie!
    This post was edited by an admin on December 22, 2013 10:13 AM.
  • Spence Spence @ 12:50 PM
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    LA Charging

    Show me an IOM that recommends a charging jacket, blanket, newspaper, etc. that isn't 20 years old. Convince me that a "band aid" that blocks air flow is what your maker recommends. Prove to me that weighing in, which is what your manufacturer wants in low ambient temperatures, is not the most accurate, or all packaged units would not come pre-charged. Sub cooling remains the same as long as the tubing length is within tolerances and you've added the proper additional charge.
  • Harvey Ramer Harvey Ramer @ 10:08 PM
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    So here is

    A million dollar question. What if it is a mismatched refrigeration unit and there is no manufacture data available. Specifically, a commercial walk in cooler operating on R-22 and another one running on R-404

    How is one too accurately calculate the proper target sub cool?
  • Techman Techman @ 6:50 AM
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    How can the SubCooling be the same for a 15' lineset that has a 10' vertical rise , and a 50' lineset that has a 30' vertical rise?
    In refrigeration work , I don't recall very many times that a given SC is desired and tried to be reached, as compared to simply having a full liquid line at the TXV and the resultant SC is what it is! Assuming  ,normal ,stableized operating temps and pressurers. So why can't the same hold true for refrigeration and AC
  • N/A @ 9:59 PM

    my advise to you young fellas

       Wait and do it when its 75 degrees outside, now we are talking about a central ac unit not a walk in cooler correct.  Over 50% of the equipment I work on is not matched any ways. Now I am not trying to be a hard tail but when its 20 outside and you to hot in you house either turn the heat down or open the front door.

       Come on fellas use your head, get the cotton out of your ears and put it in your mouth, now some commercial applications require low ambient cooling but how many of you folks work on 20 tons and larger. I am not picking on anybody but please go back and charge the ac unit in the spring.

       If you are going to weigh in the charge on cooling only equipment and have the name plate charge;  remember that is for a matched air handler and usually a 25-30 foot line set depending on the equipment name brand.  Now if its package equipment no worries provided no one has tried to re-design the unit.

       You folks should come to the deep south where we have real heat, hymn I remember why I am doing mostly boilers and electrical work ( LMAO ROTF ) 

       Big reminder folk 2015 coming soon and you folks will see how high R-22 will go up. Now if any of you out there need help charging a 2 ton ac unit up and its 15 below outside and need some help shoot me an email, I promise I will get back to you before spring.

    Peace Be With You Fine Folks

    This post was edited by an admin on December 27, 2013 10:01 PM.
  • Techman Techman @ 1:35 PM
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    cold out

    Hi David. I do agree charging a res AC in 75* or higher is a nice way to do it. But, here in L.I. N.Y. we don't have that many 75+ days in September-May. The TinKnockers that I do the refrigeration part of Res AC's for, WILL ONLY PAY when the job is done. So I hand them a bill for a completed job, AC work is just hi temp refrigeration to me!  Every mfrg of TXV's require a full liquid line. Been doing the 1 Tin guys work for 30+ years, must be doing something not wrong , right?

    Now, back in the day it was much harder to properly charge the orifice type metering device systems in low ambients.
    This post was edited by an admin on December 28, 2013 1:47 PM.
  • N/A @ 3:46 PM


       First happy holidays, second you  know like myself and a few others
    TX require sub cooling and its not rocket science hmm maybe it is to others ( lol ). By the way I wasn't referring to your comments ( lol ) Its them other Freon packers out there in the world that need the help you are like me what we need is new body parts we got enough experience  


    This post was edited by an admin on December 28, 2013 3:47 PM.
  • Eugene Silberstein Eugene Silberstein @ 6:28 PM
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    New Body Parts?

    We can get new body parts?!

    Where do I sign up? Put me down for a new back and a pair of knees!
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