System Pressure R-410A 1

[Noah ali]

HI Everyone ,

I have Gree Concealed duct type AC units , runing on R-410a , what are the working pressures for the 410a on the liquid side and on the suction side ( all tech have there own ideas what the pressure should be ) , how we come to a conclusion that the system charge is ok


the problem is that the units are not cooling at all ( thermostat set at 16-18C and room temp stays at 30-31C
the other day i took the following reading on a 4 ton ac unit

high side pressure : 250 psi
high side actual line temp near the indoor unit : 25 C

low side 150 psi
low side actual line temp on suction : 10 C

lets say i have a freshly vacuum unit i need to charge , what parameters should i be looking at inorder to now that chrage is ok ,

the unit have electric expansion valves

plus the outdoor unit have no details for subcooling and the mentioned opr/press id very high , * Attachment *

please advice

 

[dbill74]

First thing, convert psi to MPa. Better yet use a pressure gauge that reads in Pa/MPa. Using the same system of units solves so many problems and answers so many questions that get posted here.

4.2 MPa is the operating pressure (right on the nameplate). If the pressure you are getting is down 10-15%, you probably need more refrigerant. Consult your user's manual to be sure or call Gree Electric Appliances, Inc. of Zhuhai.

Second, you are looking at a heat pump. Verify the system is in cooling mode.

 

[IRstuff]

http://www.hvaceducationaustralia.com/Resources/PDF/The Essentials Of Working With 410A.pdf

states that the working pressure should be around 410 psig, which is consistent with 4.2 MPa maximum allowable pressure.

Note that your picture of the nameplate also clearly shows an operating pressure (hi/lo) rating = 4.2 MPa/2.5 MPa, which implies the operating pressure is supposed to be between 609 psig and 363 psig, so your measured pressure is well below the manufacturer's nameplate pressure.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[Noah ali]

1st i could not find any datasheet or user guide online ( regarding the unit charge for the specific unit ) ,

and the mentioned pressure are way to high , since i already tried to charge on these pressure and it give continuous error for high pressure ,

 

[MintJulep]

What is the outdoor temperature around the condenser?

PT chart for R-410A.

http://www.arkema.com/export/shared...ls/Forane-410A-Pressure-temperature-chart.pdf

If your low-side readings are accurate it seems your expansion valves are not working correctly. Are their temperature sensors installed correctly?

 

[IRstuff]

"and the mentioned pressure are way to high , since i already tried to charge on these pressure and it give continuous error for high pressure ,"

Your high side temperature is basically room temp, so you're essentially doing zero compression. Otherwise, the high side would be quite hot, from the work added by the compression process.

TTFN (ta ta for now)
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[Noah ali]

@MintJulep

the out door temp was around 47-48c * very hOt *

@IRstuff

But as high as mentioned in the nameplate i believe its way other the operating pressure for 410

 

[IRstuff]

I don't understand what you wrote.

https://www.rses.org/assets/r410a/R-410A.PDF

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[MintJulep]

Condenser temperature is 25C while outdoor temperature is 45.

First law. No heat is leaving.

Read dbill74,'s post again.

 

[EnergyProfessional]

You need to have a tool that measures pressures and the lien temperatures. That tool has a database and calculates superheat and subcooling. the device manufacturer tells you what subcooling or superheat you need to have. You should do that under load.

Hope you are not charging yourself, you need to be EPA certified and need to know what you are doing. Testo and other companies have the tools.