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  1. #1
    Join Date
    Jun 2007
    Location
    Williamsport, PA
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    172

    Looking For Opinions

    I have a couple racks that I have started working on lately that have liquid line solinoids on hot gas defrost circuits. They have check valves around them
    but I do not see why they would be needed. Is there an advantage to that set up and what is it. I was planning on removing them unless there is a good reason to have them that I am missing. Any opinions would be welcome.

  2. #2
    Join Date
    Mar 2003
    Location
    Cochrane, AB
    Posts
    605
    During defrost, the flow in the liquid line is likely reversed, hence the need for check valves. A photo would go a long way.

  3. #3
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    172
    I guess i was not clear, I am wondering why you would want the solinoid. I know you need a check valve around the solinoid in a hot gas defrost set up.
    Most of the racks I see have nothing on the liquid lines.

  4. #4
    Join Date
    Mar 2003
    Location
    Cochrane, AB
    Posts
    605
    The solenoid is probably there for store staff to turn off the system, if needed. Occasionally I see this solenoid being used for defrost or temperature control, but not very effectively.

  5. #5
    Join Date
    May 2003
    Location
    Utah
    Posts
    735
    Solenoid valves are there for pumpdown only, and likely only pumpdown when needed to isolate a circuit.

    While they are not necessary for defrosting the circuit, equipment manufacturers typically put them on the rack as a matter of habit....

  6. #6
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    172
    Thanks for the help, doesn't sound like they are needed. I am going to remove them they seem to be restricting refrigerant flow during refrigeration cycle. The liquid line is sweating after the solinoids. Not all the time but when it does happen the cases start to warm up.

  7. #7
    Join Date
    Oct 2011
    Location
    East Charlotte Area of NC
    Posts
    456
    If it ain't broke... Don't fix it.

    There are a lot of racks out there running with the configuration you have. It works, it doesn't restrict anything that much to necessitate spending all that time and money removing something the manufacturer installed. Rack has run for years with them, right?

    Why are you wanting to remove them? Are you having a problem or are you just not used to them being there?

    I can't fix it if it won't stay broke..

  8. #8
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    172
    Yea, they are giving me a problem. They are restricting the flow of refrigerant sometimes. They will woork fine them all the sudden the liquid line
    gets cold after them, the cases start to warm up, If you turn off the ball valve just ahead of them for just a second they will start working again. I think somehow the diaphram is floating inside the valve and getting stuck in a partialy open position.

  9. #9
    Join Date
    Mar 2006
    Posts
    18
    Are the check valves on piped to both sides of the liquid line solenoid or does one side pipe to a common header.

    I have worked on older racks in Food Lion where the return gas from the liquid line returned to a header on the discharge line, not the liquid header. This was to ensure that no flash gas entered the liquid header.

    Is the check valve flow opposite of the solenoid valve? If so the other reason I can think of is if they use the liquid line solenoid for temp control or for the store to turn off the circuit, the check valve ensures flow when the solenoid is off during defrost.

    I would replace or rebuild the solenoid if it is sticking.
    The largest room in the world is the room for improvement.

  10. #10
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    I'm trying to picture in my mind what could possibly cause the issue you're seeing...and coming up with too many variables to list without being there to see it with my own eyes.

    Bottom line tho, I've worked on countless racks with the same setup you have over the last couple of decades and never ran into an issue with a valve intermittently restricting refrigerant flow.

    I have this gut feeling that cutting out the LL solenoid valves simply isn't going to be the answer you're looking for.
    "The problem is the average person isnt tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and its not in the movies they watch, and its not in the few books that they buy, they dont get it" - Jack Canfield

  11. #11
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    172
    There could be other factors that are contributing to the refrigerant flashing at the solinoids. But at the end of the day if they are not needed and are one of the factors why not take them out. Basicly i was looking for someone
    to give me a good reason to leave them in.

  12. #12
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    Quote Originally Posted by johndief View Post
    There could be other factors that are contributing to the refrigerant flashing at the solinoids. But at the end of the day if they are not needed and are one of the factors why not take them out. Basicly i was looking for someone
    to give me a good reason to leave them in.
    I understand what you're saying, and other than pump down via circuit switch I don't see a reason why they absolutely MUST remain in the system.

    That said, I'm looking at it more from a viewpoint of who is going to pay to have this work done? If you're doing it on your own time....no problem. If, however, you're charging the customer to take out OEM valves - and heaven forbid this doesn't remedy the problem in it's entirety - things could get a little hairy.....both from a financial as well as a customer relations standpoint.
    "The problem is the average person isnt tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and its not in the movies they watch, and its not in the few books that they buy, they dont get it" - Jack Canfield

  13. #13
    Join Date
    Jun 2007
    Location
    Williamsport, PA
    Posts
    172
    They are not oem valves. It is a traditional rack with loop piping. The valves are in the compressor room right before yje liqid line go into the pit.

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