RE: Oversized Receiver? Not circulating refrigerant

So we are building a very large system with a 15 ton scroll compressor, liquid cooled condenser, a liquid evaporator (Chiller),  receiver, filter drier, and an electronic expansion valve.

We’ve charged the system with the approximate amount of refrigerant (5 kg) and what we’re seeing is when we turn the compressor on (EXV 100% open) it moves everything to the discharge/condensing region of the system, but won’t recirculate back through the EXV/evaporator to the suction side of the compressor. (Our suction pressure drops below 0 BarA while our discharge/condensing region will be between 8-10 BarA).

We’ve gone in and isolated system parts and flown nitrogen through them to ensure there is no blockage, so we’re very confused as to why we’re not seeing any re circulation through the system…

Is it possible that our liquid line receiver is too large and not allowing liquid to flow through the EXV?


Our other theory is that our compressor isn’t operating correctly and is just moving the liquid to the discharge side, but not providing a high enough pressure to push through.


Any help or further idea to diagnose this would be very appreciated.

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1 Answers

I always try to start with the known and/or desires conditions:

What type of refrigerant

Intended use

Target Evaporator Temperature

Target Condensing Temperature



The load/Temperature of the space/process of whatever is being served by the evaporator

Ambient Outdoor Temperature


A wild guess would be that you simply don’t have enough refrigerant  (117.6 to 147 psig condensing temperature)  Of course, this depends on the refrigerant type and it’s difficult to begin to diagnose without knowing the correct saturation temperatures and what the unit is supposed to do.





Rookie Answered on October 25, 2018.
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