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skysurfer81
12-02-2012, 04:03 PM
At the moment iīm building a diy heat pump - Itīs a compact unit (non split) and at the moment i design the refrigerant circuit for it.

Iīve looked at some manufacturers and they have bypassed the expansion valve and filter drier with a liquid line and check valve.

Does anybody know why?

AlexG
12-02-2012, 05:01 PM
This is because of one-way TXV and filter drier.

skysurfer81
12-02-2012, 06:00 PM
I saw it also with a biflow eev. did something happen when itīs going through the filter drier?

skysurfer81
12-02-2012, 06:07 PM
8612

But why they doing it?
Itīs an full biflow eev and biflow filter drier

AlexG
12-02-2012, 07:17 PM
what is 13? Check valve?

skysurfer81
12-02-2012, 07:20 PM
Yes --- Danfoss NVR6 - Check valve

skysurfer81
12-02-2012, 07:21 PM
Its from an air water source heat pump

AlexG
12-02-2012, 07:23 PM
and what is flow direction? Up or down? It opend on cooling or on heating?

skysurfer81
12-02-2012, 08:53 PM
open direction is down / cooling (defrost)

AlexG
13-02-2012, 06:11 PM
If it is reversible unit (I mean it can work in heating and cooling mode), I dont know what is this. If it is heat pump with defrost, I can assume this is like capillary tube in frige, because filter-drier is after EXV. It is too high resistanse for liquid/gas mixture. In your case you dont need it. More important is liquid separator on suction line.

skysurfer81
14-02-2012, 05:50 PM
Hello Alex... i think itīs also different what type the heat pump is.

Reversible only for defrost and Reversible for heating and cooling?!

I saw also some example that there is a second valve is installed. But between is the liquid receiver and filter drier.

?!


If it is reversible unit (I mean it can work in heating and cooling mode), I dont know what is this. If it is heat pump with defrost, I can assume this is like capillary tube in frige, because filter-drier is after EXV. It is too high resistanse for liquid/gas mixture. In your case you dont need it. More important is liquid separator on suction line.

AlexG
14-02-2012, 07:23 PM
If it is solenoid valve I can guess before defrost warm liquid is pushed to cold coil to start defrost before compressor start to improve defrosting. If u have piping schematic diagram of mentioned heat pump.