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Thread: stupified

  1. #14
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    Dec 2000
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    phoenix, arizona
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    yes, it can be done

    Quote Originally Posted by valdelocc View Post
    yeah there is a trick and all you need is a good thermometer, refrigeration guys do it all the time.
    Many years ago, I worked on an RTU on top of a large outlet store shopping center. While I was there, the in house shopping center maintenance supervisor stopped over to chat with me.

    He carries a tiny tool bag, and a CPS temp seeker TM250. ( a four station multi-port Digital thermometer), No manifold gage. He showed me how to check charge with temperature only.

    Basically, he hooked up a temperature probe to discharge port at the compressor, a probe at bottom of condenser, temp probe at Suction (maybe 1-2 feet from the compressor).). He could tell if it system is over charged, or under charge. His word to me was: temperature, temperature, temperature. He would say something like ; this one is probabbly two pund short, this one is probably 3 pound short. by garr ...lly, he was right on the money.

    I ask him why he doesn't take care it himself; His reply was; if the shopping center knew he can do all these stuff, they simply add xtra work without more compensation. So they always hire an outside contractor.
    Decide what you want, decide what you are willing to exchange for it. Establish your priorities and go to work." H.L. Hunt

    "In order that people may be happy in their work, these three things are needed: They must be fit for it. They must not do too much of it. And they must have a sense of success in it." John uskin

  2. #15
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    Nov 2004
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    Quote Originally Posted by Chris_Worthington View Post
    Just a simple question:

    If I have hoses with quick connects/ball valves with "X" gas in the hoses and I dump the liquid back in.....

    What on average am I losing here?
    hard to tell, assuming you have short hoses, maybe an ounce or???, enough to screw up a critically charged unit, no a big deal with AC but thats a different subject.

  3. #16
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    Nov 2004
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    Quote Originally Posted by jayguy View Post
    nope. unless the unit has unit mounted gages (which never seem to be accurate) or unit mounted pressure transducers (which are rarely on the liquid line), i don't see how that would be performed.
    think about a chiller with thermistors only, no pressure transducers,the module translate temperatures to pressures for you perusal, plenty of them out there.

  4. #17
    Join Date
    Jul 2007
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    Mount Airy, MD
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    7,281
    Does not Fluke and/or others have pressure transducers for measuring pressure?

    That piping in between the ones I have seen has been about a 1/2 inch.

  5. #18
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    Quote Originally Posted by valdelocc View Post
    think about a chiller with thermistors only, no pressure transducers,the module translate temperatures to pressures for you perusal, plenty of them out there.
    i know exactly what you are talking about...keep in mind that you are assuming that the refrigerant is ONLY the nameplate refrigerant and that there aren't any non-condensibles, no water tube leaks, etc. but if we are going to just go around assuming things, then why do the customers need us? my wife assumes plenty of things about me that aren't true either.

    if you are the only one taking care of the unit, then perhaps you can use the two temperature method. but even chillers that use only thermistors have problems too when the therminstors go bad and the unit doesn't know it.

    also think about what you are missing. gages will show pressure swings much faster than waiting for the txv to stabilize and give you solid temperature readings that will tell you accurate information.

    i am not against the 2 temperature method...it has limitations and in some cases, very serious limitations.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  6. #19
    Join Date
    Aug 2012
    Location
    west burbs,il
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    That seems sketchy to me cause your already working with a margin of error of staying around your targeted number for sh/sc, but adding another margin on top of that first margin hmmm.. I don't know. So instead of working with a 3 degree margin of error you may be above or below. If target is a 14 degree sc you got 13-15 to play in, but with that additional margin added by just doing temp probes whats the possibility of a false reading and it telling you that ur below your target temp or above when you were perfectly fine to begin with. I know 410 systems are tricky just like refrigeration units, if your off a few oz. your in for headaches.

    Also how do you know your getting accurate readings with only thermometers when you have to guess where the sweet spot is at? Thats a whole lot of probing around. If it does work sounds more likely to be used in a controlled setting in a manufacturing plant where its the same old units running off the line for quality checks. I see diff ambient temps inside/outside of stores, in restaurant kitchens,coolers built into stoves... refrigeration has to be on the money and seems to risky.

  7. #20
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    Tallahassee, FL
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    *

  8. #21
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    Apr 2012
    Location
    winnipeg
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    well i hate to say this ...this old man slaps the gauges on as soon as i get there unless its dead... . been doing it all my life... gauges are my eyes
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  9. #22
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    Aug 2012
    Location
    Palmyra, Missouri, United States
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    224
    guages guages guages.. pull it out read psi... suck it back in.

  10. #23
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    Apr 2012
    Location
    winnipeg
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    oh man huh
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  11. #24
    Join Date
    Aug 2012
    Location
    Toronto, Canada
    Posts
    81
    I agree that gauges are the last thing to be used..... Doesnt make sense to hook em up only to find out ur filters are plugged , or economizer is wide open yada yada!

    X2 on insanity's post about guessing the sweet spot. Use ur gauges

  12. #25
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    May 2004
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    Salt Lake City/Tooele
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    I guess I have seen these posts and I partly agree. I will keep my manifolds in the truck and only grab them if I need to do some deeper diagnostics. Like my 60 pound VETO, I don't haul that until I know I need my arsenal of tools. I have a small tool pack with my Fieldpiece w/amp clamp, Pipe clamp thermocouple, wire strippers, Klein 11 in 1, jumper wires, king-valve wrench, crescent wrench, mini-digital psychrometer, and last of all my custom built quick check pressure gauge. Gauge does upto 800psi so covers the spectrum of 99% of what I would attach it to.
    This is how I was taught to make quick SC/SH readings, without hauling a manifold and a ton of tools around. Can quickly jump around the multiple ports of a semi-herm or be in the bowels of a unit at a suction port near the TXV, or on a commercial refer evap getting SH right at the port there.

    I don't know how others do it, but I always like to know my pressure and temps, only way to see what the system is doing.Name:  0927122133.jpg
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  13. #26
    Join Date
    Jan 2010
    Location
    Toronto,Ontario Canada
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    355
    so ur saying that if u come to a unit and the filters plugged or ur contactor is blown then u are allowed to put ur gauges on. does that make sense? i dont think so. there is no need to put ur gauges on every single time thats what im saying.
    Get er Done!

    Do what has to be done
    when it has to be done
    as well as it has to be done
    And doing it all the time.

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