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  1. #1

    checking High & low side pressure

    First day running service and I don't start school until next sept. Can you take pressures at the condenser and get accurate measurements when the lineset is 25-30'? Shouldn't a lot of readings be taken at the evaperator? The tech I was with said there were no schraders at the evaperator and that was his only access to the system. I'm still dumber than dumb and didn't want to question him on my first day but how do you know what is going on at the evaperator if you only measure pressure and temp at the condensor?

  2. #2
    Join Date
    Jan 2004
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    Lancaster PA
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    Except for a few units, you won't have schrader fittings anywhere but at the condenser.

    In school they will tell you to allow a 2 PSIG pressure frop on your vapor line.
    Some systems you won't have that, others you will have moe then that.
    Liquid line doesn't have as much as a presure drop.

    Most charging charts are for measurements at the condenser.

    To go into more would be more then allowed in the open resi forum.
    Get your post count up to 15 and apply for pro membership. Then you can ask questions in the pro tech forum.

    You may even want to tell the tech your working with about this site.


    be fore warned though. It takes a thick skin sometimes. As some answers are given very sarcastically.
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  3. #3
    Join Date
    Jan 2008
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    Quote Originally Posted by phantoms001 View Post
    First day running service and I don't start school until next sept. Can you take pressures at the condenser and get accurate measurements when the lineset is 25-30'? Shouldn't a lot of readings be taken at the evaperator? The tech I was with said there were no schraders at the evaperator and that was his only access to the system. I'm still dumber than dumb and didn't want to question him on my first day but how do you know what is going on at the evaperator if you only measure pressure and temp at the condensor?
    you have alot to learn,as we all do
    this is a great place to start
    the low side gauge shows whats going on in the evap,as well as taking temp readings
    my 2 cents:read everything you can get your hands on,it will only help
    The government works for me. I do not answer to them, they answer to me.

    we need a few more sheep dogs to keep barking at the wolves,and the stupid sheep

    A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms, shall not be infringed.

  4. #4
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    Quote Originally Posted by phantoms001 View Post
    First day running service and I don't start school until next sept. Can you take pressures at the condenser and get accurate measurements when the lineset is 25-30'? Shouldn't a lot of readings be taken at the evaperator? The tech I was with said there were no schraders at the evaperator and that was his only access to the system. I'm still dumber than dumb and didn't want to question him on my first day but how do you know what is going on at the evaperator if you only measure pressure and temp at the condensor?
    I only check pressure at the evaporator (if avaliable and usually not) only if I'm checking superheat or looking for a restriction. Connecting at the condenser is standard. Your pressures will be almost the same at the expansion device inlet as it is comming out of your condenser. And the same at the comprssor suction inlet as it will be comming out of your evaporator give a few pounds differance.

  5. #5
    Join Date
    Sep 2005
    Location
    Texas
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    2,793
    so true beenthere but as the good book says, "iron sharpens iron"

    GOOD LUCK NEWBIE!!!!

  6. #6
    Thanks guys, How would you feel if a guy on his first day was questioning what you were doing? I just wanted to ask somewhere to make sure what I was learning out the gate was correct.

  7. #7
    Join Date
    Jun 2005
    Location
    SW Wisconsin
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    5,025
    I am finding that all they do is check suction pressure & maybe feel the suction line.

    They have a blank stare if you mention superheat & subcooling, & have nothing to take those line temps with! The first thing I did was put the thermo-sensors on both lines, preparing to to check both SH/SC.

    Do they teach checking SH & SC in tech schools now?

    How many don't have anything to check even the duct velocity, nor the static pressure.

    The cooling season is short here in SW WI, perhaps that be part of it.(?)
    - Darrell

  8. #8
    Join Date
    Feb 2006
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    Phoenix,AZ
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    Quote Originally Posted by phantoms001 View Post
    First day running service and I don't start school until next sept. Can you take pressures at the condenser and get accurate measurements when the lineset is 25-30'? Shouldn't a lot of readings be taken at the evaperator? The tech I was with said there were no schraders at the evaperator and that was his only access to the system. I'm still dumber than dumb and didn't want to question him on my first day but how do you know what is going on at the evaperator if you only measure pressure and temp at the condensor?

    How does one even become a service tech without going to school? I thought it was mandatory when i started. But i guess not. I know installers do not have to go to school.

  9. #9
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    Jan 2008
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    Quote Originally Posted by kbghdg View Post
    How does one even become a service tech without going to school? I thought it was mandatory when i started. But i guess not. I know installers do not have to go to school.
    I think he is a helper
    he was with a tech
    The government works for me. I do not answer to them, they answer to me.

    we need a few more sheep dogs to keep barking at the wolves,and the stupid sheep

    A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms, shall not be infringed.

  10. #10
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    Feb 2006
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    Quote Originally Posted by HVAC2B View Post
    I think he is a helper
    he was with a tech


    Ok,
    But, he said "first day running service"
    He should have said "first day watching service tech"

  11. #11
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    Quote Originally Posted by kbghdg View Post
    Ok,
    But, he said "first day running service"
    He should have said "first day watching service tech"
    lol, a little misleading
    The government works for me. I do not answer to them, they answer to me.

    we need a few more sheep dogs to keep barking at the wolves,and the stupid sheep

    A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms, shall not be infringed.

  12. #12
    Join Date
    Aug 2006
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    Wisconsin
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    Quote Originally Posted by phantoms001 View Post
    Thanks guys, How would you feel if a guy on his first day was questioning what you were doing? I just wanted to ask somewhere to make sure what I was learning out the gate was correct.
    Questioning what i'm doing = big problems. Asking questions = answers all day long.

    Just take note of what he's doing, ask questions and don't be a smart a$$. After all, you know nothing right now.
    Buy American! The job you save may be your own.

  13. #13
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    Sep 2005
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    Texas
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    Quote Originally Posted by udarrell View Post
    The cooling season is short here in SW WI, perhaps that be part of it.(?)
    - Darrell
    for some reason I wish we could have a short cooling season this year

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