Original message
| tralex
 |  "charging dose"
, posted Fri 4 Feb 08:57  
Need advice how I can determine charging dose R404A for island showcase. The unit have 2 contour evaporator and 2 built in compressors.
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Replies:
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| cneiner
| "Re(1):charging dose" , posted Fri 25 Mar 20:39
quote:
Need advice how I can determine charging dose R404A for island showcase. The unit have 2 contour evaporator and 2 built in compressors.
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The information you provided is very little to go on. It sounds like each unit is fairly small. Start with about 12oz just to get the compressor running.
Then start adding to that slowly until you start to see some subcooling out of the condenser or receiver. Then it depends on the metering device. It also depends if you have a reciever.
If it's a cap tube, start with obtaining the subcooling. Let it pull down for as long as you can. Then add refrigerant until you get a couple degrees of superheat at the outlet of the evaporator. Keep an eye on the head pressure and don't flood the compressor. The superheat will get lower and lower as the coils load with frost.
You have to make sure there is enough refrigerant to cool the case, but not so much that it floods out of the evaporator as it loads with frost before the next defrost or thermostat cycle.
Those cases are best fine tuned after they have pulled down the heat load of the case. A little flashing in the site glass would be normal for a few minutes after a defrost or a thermostat cycle.
R&D Hussmann
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| ACTECH4U
| "Re(1):charging dose" , posted Thu 10 Feb 18:55
READ THE IDENTIFICATION TAG IT MAY HAVE THE SYSTEM CHARGE BY WEIGHT.
ACTECH4U
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