pressure in the system

[19730206]

Hi experts,
I have deal with 2 multi-decks.
They have system with capillary tube. They work good.
I checked pressure in the system through Shrader valve on the compressor.
The evaporating pressure of each during work is 3,3 bar.
But when I stoped multi-decks for 48 hours and checked pressure in the system. It was different (6.0 bar and 6.4 bar). Why? The system has equal amount of refrigerant (R22) and multi-decks are staying near.
Which factors can influence on it?
I'm using the same gauges for reading the pressure.
May be sunlight is small heat source?
I know multi-decks was charged by Galileo TP fluid refrigerant charging machine.

Thanks for any advice.

 

[imok2]

I would suspct either non-condensible(air) or a slight difference in ambient temperature, I see no need to fret if they are doing a proper job

 

[waross]

Do you have a crank-case heater?
yours

 

[19730206]

Hi waross,
I havn't crank-case heater.
Thank you imok2 for answer.
May be mutual solubility freon and oil is having influence at the pressure?

 

[Drazen]

You are measuring parameter that is not controlled (machines are not working). It can even be that the refrigerant charges are not exactly the same.

But what really matters is operating parameters during work duty, which appear to be OK.

So it is almost certain that you should ignore that findings.

 

[quark]

I agree with imok2 and Drazen. The standing pressure (that is what we call it when the machine is not running)is not an issue.

Like Drazen suggested, this generally results from unequal refrigerant quantities. How did you check the quantity of refrigerant in both the systems? I am not knowledgeable about the refrigerant charging machine you mentioned. Is there any mechanism with in that machine that can tell you about the quantity of refrigerant in the machine?

If it is by suction superheat, there are fair chances of variation.

 

[bukac1]

It seems to me that you may have either not enough refrigerant in the system or system contaminated with air.
A non-working system with correct charge shouldh read (at 70F ambient temperature) 9.38 bar. Under-charged system will read less.
A working system has pressures at evaporator and condenser that depend on temperatures. If you know temperature of evaporator and condenser, you may find (saturated) condensing and evaporating pressures from tables of R22 refrigerant.
Good luck