Page 2 of 2 FirstFirst 12
Results 14 to 17 of 17
  1. #14
    Join Date
    Oct 2001
    Posts
    16
    I didn't know Hill used that type of valve. The results would be the same though.

  2. #15
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    Every manufacturer in the world uses that type of defrost differential regulator, or one of it's relatives.

    That should be an OLDR.

    That should be deenergized when in defrost. When deenergized, it is creating a differential.

    In conjunction with the OLDR, there should be an ORI in the condenser dropleg, and an ORD from the discharge line to the top of the receiver.

    You most certainly CAN defrost cases with hot gas, with no differential. The pressure will find it's way back through the liquid line. I take care of several racks that are twenty years old and never had any type of defrost differential regulator on them. They would be nice, but they work without them. (Very short runs, BTW.)

    The OLDR, the ORI, and the ORD are important when operating in low ambients, although these old pigs that I'm talking about were never told that they wouldn't work, so they just do.

  3. #16
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    Originally posted by condenseddave
    Every manufacturer in the world uses that type of defrost differential regulator, or one of it's relatives.

    That should be an OLDR.

    That should be deenergized when in defrost. When deenergized, it is creating a differential.

    In conjunction with the OLDR, there should be an ORI in the condenser dropleg, and an ORD from the discharge line to the top of the receiver.

    You most certainly CAN defrost cases with hot gas, with no differential. The pressure will find it's way back through the liquid line. I take care of several racks that are twenty years old and never had any type of defrost differential regulator on them. They would be nice, but they work without them. (Very short runs, BTW.)

    The OLDR, the ORI, and the ORD are important when operating in low ambients, although these old pigs that I'm talking about were never told that they wouldn't work, so they just do.


    [Edited by Dowadudda on 08-16-2004 at 09:03 PM]

  4. #17
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    Originally posted by jsnmrphy
    Hey guys,
    I am in need of some assistance on an old supermarket rack, I wonder if anyone can help. The model# is DA4A000RCM, am having trouble with it flooding the compressors when it comes out of defrost. should mention that only 2 circuits on this one have hot gas defrost, everything else is off cycle. I have a sporlan head pressure control in the liquid line but it does not seem to be working therefore my liquid line pressure is exactly the same as the dicharge line pressure which I believe is not allowing the condensed liquid refrigerant to come back to the system until I come out of defrost. That is what I think but I do not have any literature on this equipment so I am not really positive that I fully understand the sequence of operation. If anyone can help either with printed material or with advice it would be greatly appreciated. My fax#is 256-341-0616 & I am willing to pay for any info. Thanks Jason
    So you have a hold back on your drop leg. And with it I bet you have an ord off disharge line that dumps into receiver. Neither one of these means squat until winter. That drop leg wants to be the same right now. As the pressure falls below a certain point, she will throttle and hold back liquid, reducing effective condensing, raising head, and since I am doing that with all my liquid on roof, I need to keep enough pressure on receiver to push what liquid is in there out. These two in conjunction are nothing more than a headmaster. Doesn't have anything to do with Hot Gas.

    You should be seeing a Parker big ole blue valve, piped right off your dishcharge line with a solenoid on it. What it does is, it will drop regular dishcharge gas, by redirecting it to hot gas manifold. Hot gas goes out to case and does it's thing, it comes back and dumps back into liquid. That pressure should exceed normal liquid pressure so as to have differential and so we got flow of hot gas.

    I totally misunderstood you, and I probably even confused myself.

    That drop leg valve your seeing is precisely what you said it is, a valve to control head pressure. Head pressure if it falls below a certain point. It holds back. It stacks your liquid to increase head pressure. But doesn't do anything for you unless were talking low ambient.

    Dave was explaining that a check valve might be seeping. Generally the hot gas goes out after the suction stop, flows out to case and exits the coil before txv through a check valve and back into liquid line at rack. If the check aint holding, the liquid can enter coil and on back into coil and back to rack.

    Here is a IOM of Heatcraft and their rack systems.

    http://www.heatcraftrpd.com/Maintena...s/H-IM-72B.pdf


Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event