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  1. #53
    Join Date
    Jun 2008
    Location
    NC
    Posts
    30
    If you don't know how to properly purge your hoses and manifold, you must be a DIY'er. Which last I heard wasn't allowed on this site. So, please move on!!!

  2. #54
    Join Date
    Aug 2008
    Posts
    79
    I am universal EPA certified, PM and 410A through mainstream so I would say I am not a DIY as you say!!

    Soon I will be MVAC and Clean air Certified.

    If a 10 year old experienced tech showed me how to purge the lines then I guess he was incorrect then right? He purged right at the manifold by slowly unscrewing the flare then quickly fastening it.

    If I were to do this without knowing anything I would connect all the lines. Then slowly open a valve for example the 4th port valve on a 4 port manifold and purge that way. So that all the lines would purge simultaneously. That is only if all the other valve ports were open of course so that everything would flow out of the 4th port. I could experiment with this with plain pressured air to prove to myself this is a correct way to do it. And if you are going to ask no it would not be connected to the HVAC system, recovery device nor recovery tank during my experimentation.

    That is why I asked what the correct procedure was. Maybe the tech that showed me was incorrect? This site is just killing me.

    I belong to over 100 forums on the net in all areas of interest and this is the first forum I have run across with the strangest attitude.

  3. #55
    Join Date
    Nov 2007
    Location
    Austin Texas
    Posts
    54

    Air

    You said - "What would the smallest amount of air in the system do? Would it be indicated on the pressure gauge or would a small amount go unnoticed for a short period of time then cause trouble later on, acid build up?"

    "Air" in the system effects the capacity of the condenser and an increased PD at the TXV/Piston - not the refrigerant or its "Actual" saturation points as the refrigerant only reacts to its own pressure and not the "total system pressure"...TSP - they (The refrigerant and the air) are separate entities and should be looked at as within their own separate vessels within a single refrigeration circuit. ( It may help to look at daltons law - to help understand this phenomenon). Furthermore The Air in a system remains (Trapped) in the top part of the condenser while the system is running and at the balance point (Approximately 15 minutes of run time). The gauge pressure will reflect TSP which is refrigerant pressure + Air pressure. This TSP will give you an inaccurate (or elevated) temperature pressure relationship. This could be called... "Apparent subcool" and not the "Actual Subcool"

    In short, it affects (Lowers) the capacity by taking the much needed condenser coil space from the refrigerant. Secondly, If there is enough moisture from this "Air", it will adversely affect the expansion valve/piston by forming "Ice Crystals" at the point of the pressure drop causing a variable restriction and loss of TD accross the evaporator.

    *The statement above only addresses how the refrigerant acts under these conditions - It is not addressing the acid created by moisture in that said air within the system as a byproduct of moisture and refrigerant interacting, thereafter, that in time shortins the life of the compressor by creation of hydrochloric acid, and higher compressor/system temperatures. On this note - the moisture in the system is often caught by the filter drier after many passes, except that when it is free within the system (Before it is captured) it tends to be directly accepted into the winding insulation of the stator. This will quickly break the insulation down (like water in paper) which will quickly cause a short between phase to phase, winding to winding, or directly to stator.

    The higher temperatures inside the compressor (Caused by higher pressures or TSP) also cause winding shrinkage very quickly. It is obvious that shrinking a winding will cause spot burns and direct shorts to the stator as the winding shrinks to a point of touching the stator directly at the point of entry and exit of that said winding within the stator (Top and bottom).

    Hope this helps in some small way Mr...Universal EPA guy!

  4. #56
    Join Date
    Aug 2008
    Posts
    79
    Thanks. That was a great explanation and description of what can eventually happen to a system with air in it.

    With Daltons Law I have to go back to the good all college textbook.

  5. #57
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,095
    Quote Originally Posted by havactech View Post

    If a 10 year old experienced tech showed me how to purge the lines then I guess he was incorrect then right?
    I take advise on how to play video games from 10 year olds.
    Not how to purge gauges.
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  6. #58
    Join Date
    Feb 2006
    Location
    Tn.
    Posts
    1,344
    Quote Originally Posted by DavidInAustin View Post
    You said - "What would the smallest amount of air in the system do? Would it be indicated on the pressure gauge or would a small amount go unnoticed for a short period of time then cause trouble later on, acid build up?"

    "Air" in the system effects the capacity of the condenser and an increased PD at the TXV/Piston - not the refrigerant or its "Actual" saturation points as the refrigerant only reacts to its own pressure and not the "total system pressure"...TSP - they (The refrigerant and the air) are separate entities and should be looked at as within their own separate vessels within a single refrigeration circuit. ( It may help to look at daltons law - to help understand this phenomenon). Furthermore The Air in a system remains (Trapped) in the top part of the condenser while the system is running and at the balance point (Approximately 15 minutes of run time). The gauge pressure will reflect TSP which is refrigerant pressure + Air pressure. This TSP will give you in an inaccurate (or elevated) temperature pressure relationship. This could be called... "Apparent subcool" and not the "Actual Subcool"

    In short, it affects (Lowers) the capacity by taking the much needed condenser coil space from the refrigerant. Secondly, If there is enough moisture from this "Air", it will adversely affect the expansion valve/piston by forming "Ice Crystals" at the point of the pressure drop causing a variable restriction and loss of TD accross the evaporator.

    *The statement above only addresses how the refrigerant acts under these conditions - It is not addressing the acid created by moisture in that said air within the system as a byproduct of moisture and refrigerant interacting, thereafter, that in time shortins the life of the compressor by creation of hydrochloric acid, and higher compressor/system temperatures. On this note - the moisture in the system is often caught by the filter drier after many passes, except that when it is free within the system (Before it is captured) it tends to be directly accepted into the winding insulation of the stator. This will quickly break the insulation down (like water in paper) which will quickly cause a short between phase to phase, winding to winding, or directly to stator.

    The higher temperatures inside the compressor (Caused by higher pressures or TSP) also cause winding shrinkage very quickly. It is obvious that shrinking a winding will cause spot burns and direct shorts to the stator as the winding shrinks to a point of touching the stator directly at the point of entry and exit of that said winding within the stator (Top and bottom).

    Hope this helps in some small way Mr...Universal EPA guy!

    Ah what do you know RD you rookie.

  7. #59
    Join Date
    Nov 2007
    Location
    Austin Texas
    Posts
    54
    Quote Originally Posted by m-cooling View Post
    Ah what do you know RD you rookie.

    Ill take that as an agreement!...on most of my BS!...lol

  8. #60
    Join Date
    Sep 2008
    Location
    arlington, tx
    Posts
    225
    an epa certification is a 1 day class/test that has nothing to do with the actual a/c process/system...and i was referring to this specific system and this specific operator btw...yes he was wrong when he just loosened and tightened the high and low hoses and a chiller operating in a vacuum based on the type of compressor but the type of refrigerant(besides the point but fyi) the reason you are met with these types of replies in this forum is you came in and asked people who have to fix the problems people like you create everyday how to incorrectly rig something...and btw if you read back i gave you the correct way to incorrectly rig it lol...

  9. #61
    Join Date
    Aug 2008
    Posts
    79
    Try again on the EPA test. Maybe you took yours a long time ago? You have to study for a couple of weeks. Maybe its a one day crash course but your not going to pass the exam in one sitting , good luck if you do.

    I basically studied on and off for a couple of weeks. Its not just memorizing but also understanding the concepts.

    I had to refer a lot to a HVAC textbooks to clarify things. Sure having an EPA cert. does not make you a HVAC tech but it certainly gives you general knowledge and helps pave the way.

    Ok so if that is the incorrect way to purge your hoses and manifold then what would be the correct way. No one seems to answer that question , I wonder why?

    I wonder how the EPA themselves would look upon some of these replies. I am sure they would not be so happy.

    Here is one example:

    http://www.404ster.com/?module=manua...dule=1/411/pdf

  10. #62
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,095
    Hook your hoses up.
    Purge each one through the charging hose.

    EPA. Read through book to learn dates. Seminar, then test. No weeks of study for it.
    Passed Universal first try.

    That test isn't that hard.
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  11. #63
    Join Date
    Sep 2008
    Location
    arlington, tx
    Posts
    225
    im 22 buddy i just got around to getting the epa cert a month ago the only question i missed was a date and i didnt even get the book til i walked in...that attachment proved your wrong you need to take some ice cause your head is swoll

  12. #64
    Join Date
    Aug 2008
    Posts
    79
    Thanks beenthere. no offence mechanicalgsxr. The Mainstream course was over 50 pages with several pages on review notes and over 400 practice questions. Dates are vital but there are core questions which I agree are pretty basic but some of the type I, II and II questions are obscure if you do not review the documentation.

    For example, I could not even picture in my mind what they meant by this question until I looked at examples in a textbook on the different positions.

    BackSeating of a Suction Shutoff Valve will close the:
    A) Suction Line and Compressor port
    B) Compressor and gauge port
    C) Gauge Port
    D) Compressor Port.


    The Answer is Gauge port. I did not know the terminlolgy of backseating and frontseating until I reviewed that section in the HVAC textbook showing pictures and an explanation.

    To just accept what it said in the mainstream guide was not enough for me to remember this.

    For many of you experienced you already understood this but for me I had to see why in order to understand and remeber this question.

    Just one of many that they ask on the examine.

    There asre many trick question as well and just memorizing is not enough. For me to memorize it I need to understand why so I never forget it. That is just the way I am.

  13. #65
    Join Date
    Sep 2008
    Location
    arlington, tx
    Posts
    225
    buddy i took the same test you did i know whats on it and that to someone who knows a/c equipment questions like that are not hard....look i hope that you study your ass off and become a badass tech someday but your not gonna accomplish that by doing jackass things like your filter loop(which you will someday laugh about)

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