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  1. #1
    Join Date
    Jul 2012
    Posts
    359

    Suction Line solenoid?

    In my friend's little market, one of the cases has a 120v solenoid on the suction line connected to a pen thermostat in the case. Since the case is low pressure cutout controlled I will assume this stops the suction line so the pressure drops quickly and opens the low pressure switch stopping the compressor. Wonder why someone put that on there? The compressor will go off anyway on the low cutout.

  2. #2
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
    Posts
    3,644
    If you shut off the liquid line, the coil will continue to remove heat until the liquid supply is exhausted. This will cause a the case to drop below desired temperature. When the suction line solenoid shuts off, the txv will stop the flow of liquid, as the pressures before and after become balanced.

  3. #3
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,326
    Common on deli cases
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  4. #4
    Join Date
    Jul 2012
    Posts
    359
    Ok. I see. This was an old r12 case at one time.

  5. #5
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    2,750
    Im thinking its only important on freezers to empty the evap with liquid line valve , so when the heaters come on its easier to defrost

  6. #6
    Join Date
    May 2010
    Posts
    23
    Just wondering the refrigerant would be traveling back to compressor in liquid state while that suction solenoid valve opens at temperature increase.

    Sent from my GT-I9100 using Tapatalk

  7. #7
    Join Date
    Sep 2010
    Location
    Nashville, TN
    Posts
    28
    Quote Originally Posted by gzhjb View Post
    Just wondering the refrigerant would be traveling back to compressor in liquid state while that suction solenoid valve opens at temperature increase.

    Sent from my GT-I9100 using Tapatalk
    Not really, because the suction pressure will being to rise rather quickly to equilibrium with the ambient temp within the case. That is pressure converted to temperature. It becomes the pressure or force that closes the TXV against the opening or bulb pressure. What that really means is during an off cycle defrost you have slow equalization and when the compressor is later energized the little bit of liquid that is static in the evaporator is quickly evaporated as the suction pressure drops.

    However, if your condensing unit is outdoors and your compressor has a long off cycle defrost, I would make sure you have a crankcase heater.

  8. #8
    Join Date
    Feb 2014
    Location
    Atlanta
    Posts
    127
    Just wondering...
    If the unit is equipped with a suction stop is it not a hot gas defrost?

  9. #9
    Join Date
    Jul 2012
    Posts
    359
    No hot gas defrost. I removed the suction line solenoid. Working fine. Temp is right on 36F where the owner wants it. The R422B gas is working great since the conversion.
    This is the case I changed over with three Sporlan EGG 1/2C R22 valves, a Copeland CK 16 compressor. It was previously an old semi hemi that failed running R401.

    We fixed this thing on a shoestring budget with fleabay parts.

  10. #10
    Join Date
    Jun 2012
    Location
    Tenn
    Posts
    139
    Quote Originally Posted by gzhjb View Post
    Just wondering the refrigerant would be traveling back to compressor in liquid state while that suction solenoid valve opens at temperature increase.

    Sent from my GT-I9100 using Tapatalk

    No. The evaporator will have a low pressure and the TXV will be metering into the evap.

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