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Thread: Subcooling

  1. #14
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    I'm starting to pick up some of the short hand. I'm new to the forum and new to field but it would be nice to see less of the short hand. I take any spare time to prowl the threads and pick up as much as I can. the boss don't even mind, its research to him.

    on topic how bad is it to cool 100F a crossed the condenser? the only thing I can think of is my units have massively oversized evaporators. so its ok?

  2. #15
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    Subcooling is result of what the condenser coil is trying to do, Make liquid. The more liquid in a condenser the less space the coil has to condense vapor. So excessive subcooling can reduce the capacity of the condenser.

    One of the functions of subcooling is to ensure a solid column of liquid feeding the metering device.

    Design subcooling should be the target...

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  4. #16
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    Quote Originally Posted by udarrell View Post
    They should always list the actual SC temp & the target SC temp for that unit, then there should be no confusion as to whether it is too high or too low Sub Cooling...
    At least I wouldn't be confused. Too many unknowns for some. Like how would a newer guy know what the target SC is unless they are gifted with a hi-tech manifold or were educated in the finer points of analysis. Actually it could also be seen on a chart.
    It's great when some list all the diagnosis numbers but that's a bit advanced.
    We need to remember techs might come with huge differences in education, training, abilities.
    In the time I've been attending this forum I have seen a large change in what techs are doing. Probably the future will see more.

    Measuring sub-cooling hasn't always been seen as important. Charging was usually kept to measureing superheat and evap delta T.
    It's not that sub-cooling wasn't known about but it's importance wasn't acknowledged like it is with hi-eff equipment. Mostly just grab the liq line and ask yourself "Does it feel right?".
    I should have played the g'tar on the MTV. MK

    You can be anything you want......As long as you don't suck at it.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

  5. #17
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    The target sub cooling on a TXV metered system is listed on the condenser tag, so there is no guessing...

  6. #18
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    Charge to 2 degrees superheat and get that space crispy cold!!!!
    HVAC Magician @ UA Local 638

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  8. #19
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    Quote Originally Posted by udarrell View Post
    The target sub cooling on a TXV metered system is listed on the condenser tag, so there is no guessing...


    I guess we've been working on different stuff. Do you do just new resi?
    I should have played the g'tar on the MTV. MK

    You can be anything you want......As long as you don't suck at it.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

  9. #20
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    Quote Originally Posted by hvacker View Post
    I guess we've been working on different stuff. Do you do just new resi?
    Yes, I only did residential & light commercial trouble shooting & unit replacements since the mid-1970's; I am retired now.

  10. #21
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    high sub cooling capacity loss. not enough heat may be removed. high head pressure from over stuffing the coil. easy to do with 410. I have also seen it make the txv stick.

    most every unit has their required subcool on the label. if not shoot for 10.

    Subcooling is the most important with a txv. super heat is only with a piston or cap tube.

    The original poster mentioned 100 deg from the condenser coil. Are you talking discharge temp, temp differential, liquid line temp?

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