Daikin chiller check valve

[otrotabi]

Hi everyone,

Yesterday I was checking a Daikin chiller and noticed something I had not previoulsy seen elsewhere. It is a check valve placed between the output of the receiver tank and the liquid line that goes to the EEV, while at the same time there´s a tube bypassing the receiver.

At first I thought (and maybe it actually is) a way to inject the best sub-cooled liquid you can get (directly from the condenser) but since the check valve needs a certain pressure drop to open, it looks to me that this way the receiver would actually never work.

I guess I am wrong since Daikin makes a lot of chillers, but I can not get how this works.

By the way, the chiller is heat-cool, so there´s a reversing valve as well. I tried to draw a schematic here but I am not 100% I remember correctly.

DAIKIN CHECK.jpgDAIKIN CHECK.jpg

[narkom]

I suppose the diagram you provided is not quite correct.
This is a standard one for the heat pump chiller.

Refr. diagram.jpg

Cooling.jpg

[otrotabi]

Thanks narkom

Yes, I guess this is the right P&ID. Not an easy one to understand either but hopefully makes more sense than what I gathered from the pictures I took.

I checked the manual but the circuit is not there. Where does this come from ?

Regards

[narkom]

This is from Trane CXAH manual. Since the plate evaporator and fin&tube condenser have a different internal volume, the circuit needs a receiver to store an excess of refrigerant during the cooling mode.
Regards.