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Thread: sh/sc

  1. #1
    Join Date
    Aug 2011
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    houston, texas
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    sh/sc

    isnt super heat measured at the coil when there is a txv and sub cooling measured at the condensing unit when there is another type of metering device such as cap tubes?

  2. #2
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    May 2004
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    Frederick, MD
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    No,

    it's not.

  3. #3
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    You've reached 15+ posts, apply for pro..

    Not sure what your looking for with this question. Both methods can be used for diagnostics with either type system. Typically superheat is used to measure refrigerant charge of a normally operating fixed metering type system, and subcooling for expansion valve type system. Superheat can be useful for diagnosing the proper operation of an expansion valve, and subcooling can help in diagnosing a fixed metering system. Measurement can be taken from both inside and outside. This can give you an indication of refrigerant flow and possible restrictions, excessive lift, or length etc.

    Superheat taken inside will help ensure proper and complete evaporation of refrigerant in the evaporator, and outside to ensure there is no liquid returning to the compressor.
    Subcooling taken outside will give you an idea of the system charge and the amount of heat it can reject in regards to efficiency.
    Taken inside, will help ensure there is a solid column of liquid entering the evaporator's metering device.
    Subcooling combined with superheat can be a useful tool in diagnosing overcharging, undercharging, and metering restrictions.
    Hope this helps. It's not everything about SC, and SH, but it's a start.
    "The only true wisdom is in knowing you know nothing" Socrates

  4. #4
    Join Date
    Jun 2011
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    Hammond,La.
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    You have asked three rediculous questions with three different threads. What are you looking for?
    "I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
    Benjamin Franklin, 1766

  5. #5
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    Aug 2011
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    houston, texas
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    why you say ridiculouse. i am just getting in to this field and im trying to understand. there is a lot of things going on and i want to learn as fast as i can but it seems like i get differant answers from people and its hard to tell whos right.

  6. #6
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    Jun 2011
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    Hammond,La.
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    Quote Originally Posted by el_coyote2373 View Post
    why you say ridiculous. i am just getting in to this field and im trying to understand. there is a lot of things going on and i want to learn as fast as i can but it seems like i get different answers from people and its hard to tell who's right.
    You asked this in another thread.
    i have a carrier 3 ton air handler in my attic and cant figure out how to clean the coil. there is no access what so ever. the coil is actually in the air handler. i think its a 3 year old system.
    The said this.

    wow ...lots of work... i was hoping to stick a can of coil cleaner in there and spray. then hose down with water hose.
    I can't see where this is even a serious question or statement. You plan on spraying a water hose inside the AH and didn't know the evap coil was supposed to be in there? Where else could it be? Then the no access statement?

    I will give a pass on the LRA/RLA question and maybe on the charging method of TXV and fixed metering device equipped systems even though a quick google search would have answered that question easily. Sorry but the whole coil post made me wonder it it wasn't serious and someone looking for laughs.

    If you are serious I suggest reading some HVAC theory articles and even some youtube video's of how an A/C works before asking questions so you can get a basic understanding of what is going on and how things are generally set up. Then you can make better sense of other peoples answers even when they differ.
    "I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
    Benjamin Franklin, 1766

  7. #7
    Join Date
    Jul 2005
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    Quote Originally Posted by el_coyote2373 View Post
    why you say ridiculouse. i am just getting in to this field and im trying to understand. there is a lot of things going on and i want to learn as fast as i can but it seems like i get differant answers from people and its hard to tell whos right.
    You misunderstood the answers.

  8. #8
    Join Date
    Nov 2010
    Location
    N. Idaho
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    Months ago, my instructor warned me about the amount of guys who dont understand the refrigeration cycle, or SH/SC. Also told me, if I could really get a good grasp on all that, I would be above and beyond the rest.

  9. #9
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    Jun 2011
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    Hammond,La.
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    Quote Originally Posted by Damien View Post
    Months ago, my instructor warned me about the amount of guys who dont understand the refrigeration cycle, or SH/SC. Also told me, if I could really get a good grasp on all that, I would be above and beyond the rest.
    I was told once that when the suction line starts to sweat and it's blowing cold air your good...
    "I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
    Benjamin Franklin, 1766

  10. #10
    Join Date
    Dec 2005
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    Cincinnati, Oh
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    Quote Originally Posted by Rcb2875 View Post
    I was told once that when the suction line starts to sweat and it's blowing cold air your good...
    Thats wrong wrong wrong, and you know it.

    Sweat on the suction line has nothing to do with a charge.

    It has to be beer can cold.



    Coyote:

    Are you seriously running calls yourself?

    You need to run calls with someone for a great deal longer.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

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