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Thread: DDR VALVE
07-12-2012, 06:26 AM #1
Can I replace the DDR valve with a OLDR valve on a Margaux rack? If so, what are the deciding factors wether to use an OLDR or a LDR? It seems to me a few years back I heard that you had to come back in with a DDR on a Margaux rack!!
07-12-2012, 10:17 AM #2
In order to get the condensed defrost gas back to the liquid header on a HG defrost rack we need to establish a pressure difference between the hot gas (or Kool Gas) and the liquid header.
There are two basic methods to accomplish this. One is the discharge method where you have a differential regulator (DDR) after the tee for the HG header. The other is the liquid method where you install a differential regulator (OLDR) in the liquid line upstream of of the liquid header.
They both accomplish the same thing, although the liquid method is probably a bit more energy efficient because the discharge method increases the compressor discharge pressure above that of the condenser. The liquid method however will cause a loss of apparent subcooling due to the pressure drop in the liquid feed, so its probably best you have a mechanical subcooler when using the liquid method.
Otherwise, the difference is the DDR energizes to fully open and the OLDR de-energizes to open.
07-12-2012, 05:53 PM #3
07-12-2012, 06:29 PM #4
07-12-2012, 06:44 PM #5
07-12-2012, 07:03 PM #6Professional Member
- Join Date
- Mar 2006
Only if the return gas fron the liquid line does not return to the discharge line. I have seen a lot of margaux racks return to the discharge line (Food Lion). If you have tees and check valves on all your liquid lines attached to another header use a DDR.The largest room in the world is the room for improvement.
07-12-2012, 07:39 PM #7