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Thread: subcooling

  1. #1
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    subcooling

    Just trying to clarify subcooling measurements I have been taking them after the condensor before the receiver .I ran into some refer guys the other day and we got on the subject of subcooling they told me they measure it after the receiver .Would't this change my subcooling readings by taking the measurements after the receiver ??? Should I stick to measuring it before the receiver?? Thanks
    Would the last person to leave NJ please put out the lights

  2. #2
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    If your Receiver has some kind of pressure regulator like a Headmaster, that will affect your sub-cooling measurement. If it's a straight shot Condenser-Receiver-Liquid Line, I'm not real sure it'll matter that much. Could be wrong. Interesting question....
    The views and opinions posted here are my own. They do not reflect the corporate policies of my employer and will most likely get me fired at some point.

  3. #3
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    I think after the receiver since that's where the stacking of liquid will occur. EngineerDave's correct about a flooding control skewing your readings.

    Honestly, (IMO) subcooling measurement is not that effective a tool in a TXV system with a receiver. Spend your time setting superheat and checking things like discharge temp that can fry a compressor if not right.

  4. #4
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    Thanks was looking for a ball park on my charge r404 freezer when I arrived subcooling was zero .Found leak at accumulator pumped down ,fixed and added some juice subcooling now 13 and superheat at exaporator is a 10. Sight glass still had bubbles after box got down to temp. zero degrees "don't know if it was the controversial mixed blend bubbles". Box working fine now just food for thought only fan cyling controls no headmaster on this box.
    Would the last person to leave NJ please put out the lights

  5. #5
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    Quote Originally Posted by james264 View Post
    Thanks was looking for a ball park on my charge r404 freezer when I arrived subcooling was zero .Found leak at accumulator pumped down ,fixed and added some juice subcooling now 13 and superheat at exaporator is a 10. Sight glass still had bubbles after box got down to temp. zero degrees "don't know if it was the controversial mixed blend bubbles". Box working fine now just food for thought only fan cyling controls no headmaster on this box.
    We have this "do you fill the site glass when using blends" argument all the time. Just clear the glass and check your vitals. She'll be fine.

  6. #6
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    Talking

    I know didn't want to start a sight glass posting contest .
    Would the last person to leave NJ please put out the lights

  7. #7
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    Quote Originally Posted by james264 View Post
    I know didn't want to start a sight glass posting contest .
    Good, cuz there needs to be a full column of liquid at the expansion vale. Period.
    If you really know how it works, you have an execellent chance of fixin' er up!

    Tomorrow is promised to no one...

  8. #8
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    Quote Originally Posted by rayr View Post
    Good, cuz there needs to be a full column of liquid at the expansion vale. Period.
    Ray, we needed you when this was going on.

    http://www.hvac-talk.com/vbb/showthr...=130717&page=2

  9. #9
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    Quote Originally Posted by k_fridge View Post
    Honestly, (IMO) subcooling measurement is not that effective a tool in a TXV system with a receiver.
    Agreed. Subcooling is a poor indicator of the refrigerant charge in a system using a receiver. Better to charge to a clear sight glass, and then add any additional refrigerant necessary to compensate for low ambient temperature operation. (Better yet, weigh in the manufacturer's recommended charge if applicable.) Then you can measure subcooling just to get a warm and fuzzy feeling that you haven't screwed up something.

  10. #10
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    The last time we debated the subject, we concluded that all subcooling may or may not be lost after the receiver or something like that, Andy probably remembers.

  11. #11

    Superheat and PT

    most of the time I charge with superheat and then PT chart... if your superheat is right and your pressure is good you should be alright... in warranty work I usually will just take sub cooling to put on the sheet (CYA).

  12. #12
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    Quote Originally Posted by jamesgriffin View Post
    most of the time I charge with superheat and then PT chart... if your superheat is right and your pressure is good you should be alright... in warranty work I usually will just take sub cooling to put on the sheet (CYA).
    I’m one step ahead, I charge with the palm of my hand, if it feels cold like a beer I’m good to go , I only use superheat for warranty cases.....

  13. #13
    does anyone have a pic of a sightglass that has a blend in it that has a "cloudy look" i am yet to see this

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