Recharjing AC from the R22 recovery bottle

[piezomot]

I was just recharging my AC from the R22 recovery bottle. I measured the pressure inside the bottle and at the beginning it was 148 psi at outside temperature 84 Fahrenheit. I purged all my hoses red, blue and yellow. I have connected the yellow hose of my R22 charging manifold to the vapor side and placed the tank upside down on the scale. When red and blue hoses were connected (red to the thin high side and blue to the thick low line) and the air conditioner was off I measured on red line 120 PSI and on blue line 115 PSI. When i started the AC, the red line was at 195 PSI and the blue was at 195 PSI. I started to add the R22 refrigerant from the bottle via the blue side vale in small portions and after 20 minutes of charging blue line was at 40 PSI and red was at 210 PSI. After 30 minutes of charging blue line at 46 PSI and red line at 215 psi. What is bothering me is that at the beginning the air temperature inside my house leaving the air duct was at 16.2 degree Celsius and after 30 minutes of my AC charging it was 18.6 degree Celsius. Also I was under impression that the red line pressure will go up after charging and the blue line pressure should actually go down, but in my case it went up instead. Any recommendation what I have done wrongly? Thank you for your prompt reply! Thank you again, but the delta between my start point on the blue side is 16 psi and on the red side 20 psi and on this video it was only 15 PSI on the red side. https://youtu.be/b0gsuh-Sno8

[frank]

Sounds like you have overcharged it

[piezomot]

Sounds like you have overcharged it

Why do you think so? I am just learning it, when I disconnected the manifold hoses I realized that two pressure meters were not at zero. I forgot to zero them (there is a small adjustment screw on the front fascia) before i started. Here is the corrected values: after 20 minutes of charging blue line was at 36 PSI and red was at 205 PSI. After 30 minutes of charging blue line at 42 PSI and red line at 210 psi. Also I realized that the super-heat temperature is usually about 10-12 degrees Farsighted and the measured temperature on the high side usually would change about 2 degrees Farsighted, so I came to the conclusion that there is no need to measure it.

[piezomot]

Today I measured the duct air temperature and it is 16 degrees Celsius instead of 11-12 degree Celsius. I also noticed that my return line is at much warmer temperature (it is hot) then it should be. Is this an indication that my AC compressor is not able to produce enough compression? Or this the indication that I have to re-flush the R22 refrigerant? Thank you.

[seanf]

Why are you having to recharge the system? A fault, a leak......

Is it a new bottle of R22 your using to charge the system, or R22 you've recovered from the system that your putting back in?

Did you put a vacuum pump on the system to pull out all the air before recharging the R22, or did you just purge the pipework?

Take pressure readings from the low and high side.
At the same time take pipe temperatures from the compressor suction pipe (large cool pipe), and the liquid line at the outlet of the condenser coil (outdoor heat exchanger).
Also take air in and air out temperatures from the indoor unit duct, and the outdoor ambient temp.

[piezomot]

Why are you having to recharge the system? A fault, a leak......

Is it a new bottle of R22 your using to charge the system, or R22 you've recovered from the system that your putting back in?

Did you put a vacuum pump on the system to pull out all the air before recharging the R22, or did you just purge the pipework?

Take pressure readings from the low and high side.
At the same time take pipe temperatures from the compressor suction pipe (large cool pipe), and the liquid line at the outlet of the condenser coil (outdoor heat exchanger).
Also take air in and air out temperatures from the indoor unit duct, and the outdoor ambient temp.16113

Thank you for your prompt reply! Just measured after 2 hours of the AC work:

1. The outdoor temperature 32 degrees Celsius.
2. The indoor home air temperature 27 degrees Celsius.
3. The temperature at the large cool pipe outdoor at the AC unit is 26.3 degrees Celsius.
4. The temperature at the small hot pipe outdoor at the AC unit is 39 degrees Celsius.
5. The temperature at the air duct lowest point at the top of the furnace is 18 degrees Celsius.
6. The air temperature coming out from the duct at the main floor is 22 degrees Celsius.
7. The pressure at the blue line connected to the thick line is 43 PSI.
8. The pressure at the red line connected to the think line is 200 PSI.

I have calculated that my Superheat = Measured temperature red line (102 F ) - Taken from the meter temperature red line (102 F) = 0.

I used R22 bottle which someone recovered from the system, I placed it upside down to charge the system with the liquid R22.

I did not put a vacuum pump on the system to pull out all the air before recharging the R22, I just purge the pipework.

Please advise about possible corrective action.

Your prompt reply is really appreciated! Thank you.

[piezomot]

As soon I have connected the lines and the R22 bottle I was taking the liberty to re-charge again.
16114
I have calculated that my Superheat = Measured temperature red line (98.6 F ) - Taken from the meter temperature red line (106 F) = 7.4.
Now the air temperature from the indoor air duct dropped to 14.2 degrees Celsius and the temperature at the air duct lowest point at the top of the furnace dropped to 10.2 degrees Celsius.

Should I recharge more till the Superheat will be equal 12 degrees Fahrenheit?

[Brian_UK]

You are not measuring Superheat using the red, high pressure gauge.

You need to use the blue, low pressure gauge. Where the gauge needle is shows pressure and temperature. Record that temperature and now measure the temperature of the larger suction pipe at your hose connection point. The difference between that temperature and the temperature from the pressure gauge is the "superheat".

[seanf]

What was the reason for the refrigerant being removed from the unit? was there a fault or did the outdoor or indoor unit have to be relocated. Just wondering if there has been a change in the pipework length, or if there could be a problem with the unit.

When the person recovered the refrigerant from the unit, was the bottle completely empty?

It looks like your suction superheat is about 32 Deg C. (See Brian's post)
And that your highside pressure is lower than I would expect for that ambient.

[piezomot]

You are not measuring Superheat using the red, high pressure gauge.

You need to use the blue, low pressure gauge. Where the gauge needle is shows pressure and temperature. Record that temperature and now measure the temperature of the larger suction pipe at your hose connection point. The difference between that temperature and the temperature from the pressure gauge is the "superheat".

Hello Brian, thank you for your prompt reply! I was following this video below, where the red gauge is used to measure the Superheat.

https://youtu.be/b0gsuh-Sno8?list=PL7XFU9Y6uohwdxUCNRohnCIFunBPAwjge

If I would measure the Superheat from the blue gauge and the blue line, it would be then:

Superheat = the blue gauge temperate (46 F) - the blue large line temperature (79.4 F) = -33.4. This does not make any scene.

[piezomot]

What was the reason for the refrigerant being removed from the unit? was there a fault or did the outdoor or indoor unit have to be relocated. Just wondering if there has been a change in the pipework length, or if there could be a problem with the unit.

When the person recovered the refrigerant from the unit, was the bottle completely empty?

It looks like your suction superheat is about 38 Deg C. (See Brian's post)
And that your high side pressure is lower than I would expect for that ambient.

Hello seanf, the refrigerant was never removed from the unit. I did not do any pipe work. I just realized my air conditioner is not cooling my home enough. I purchased the used R22 recovery bottle with some R22 and I used it to charge my IC via the manifold with two gauges, blue, red and yellow hoses I also purchased.

[NH3LVR]

The Video shows how to check SUBCOOLING-not Superheat.
I am not against someone learning, but you need to develop a better understand of the principals involved before you attempt to do the work.

[seanf]

Hello Brian, thank you for your prompt reply! I was following this video below, where the red gauge is used to measure the Superheat.

https://youtu.be/b0gsuh-Sno8?list=PL7XFU9Y6uohwdxUCNRohnCIFunBPAwjge

If I would measure the Superheat from the blue gauge and the blue line, it would be then:

Superheat = the blue gauge temperate (46 F) - the blue large line temperature (79.4 F) = -33.4. This does not make any scene.

Suction Superheat is how many degrees C or F you have, above the pressure related temperature you read off the gauge.
So you said you had a low side pressure of 43psi which should read about -7 Deg C on your gauge.
You said that the temperature of the large cool pipe measured +26 Deg C.
Your suction superheat is then the difference between the two readings. +7 to get you up to 0 Deg C, +26 to get you to the pipe temperature. So 7+26 gives a superheat of 33 Deg C.

[seanf]

Hello seanf, the refrigerant was never removed from the unit. I did not do any pipe work. I just realized my air conditioner is not cooling my home enough. I purchased the used R22 recovery bottle with some R22 and I used it to charge my IC via the manifold with two gauges, blue, red and yellow hoses I also purchased.

It sort of sounds like the unit could have lost some refrigerant, if that is the problem youd be better off having someone do leak checking and repairs for you. Probably safer and cheaper than doing it yourself.

I wouldnt rule out there being a different fault with the unit.

[piezomot]

Suction Superheat is how many degrees C or F you have, above the pressure related temperature you read off the gauge.
So you said you had a low side pressure of 43psi which should read about -7 Deg C on your gauge.
You said that the temperature of the large cool pipe measured +26 Deg C.
Your suction superheat is then the difference between the two readings. +7 to get you up to 0 Deg C, +26 to get you to the pipe temperature. So 7+26 gives a superheat of 33 Deg C.

Thank seanf. Originally the blue gauge showed the saturation temperature of 20 degrees F (Pressure 43 PSI R22). At the same time the temperature I measure on the blue line next to the charging port is 80 degrees F. Thus my Superheat is 80 F - 20 F = 60 F. The pressure at the red gauge before charging was 200 PSI that corresponds to the temperature of 102 F. When I charged the system from the R22 recovery bottle, the Superheat changed 75 F - 26 F = 49 F. At the same time my red gauge after charging shows the pressure 225 PSI or it is the temperature 106 F and I measured the temperature of the high pressure pipe was 106 F. Question- is my system is overcharged now of I should continue charging it?

[piezomot]

It sort of sounds like the unit could have lost some refrigerant, if that is the problem youd be better off having someone do leak checking and repairs for you. Probably safer and cheaper than doing it yourself.

I wouldnt rule out there being a different fault with the unit.

I live in a small town and nobody is around and the AC people do not want to drive 100 km for that little job from the big city. I have to learn and do it myself now.

[RANGER1]

piezomot,
Seems to me system is short of refrigerant.
Would expect suction pressure of 58 to 85 psi depending on room temperature. The closer to 22-24 deg C room temperature could be 58psi or more.
You would normally want above 58 psi suction pressure, or above 0 deg C to prevent freezing the evaporator.
Make sure air filters are clean & good airflow.
Same with clean condenser, no build up of dirt on air on side of coil Dave.

Discharge pressure 250psi okay on a hot day.
Sometimes a liquid line sight glass can show if liquid line in full, which is what you want.
You may have a very small leak that could have taken years to lose , or something bigger, that will cause re-occurring problem.
Ideally leak should be found & fixed, which may not be an option for you.
Sometimes a small oil stain, dust on oily area could be where leak is.
Can only suggest you network with others in the area that may need repairs to help keep costs down etc& make it more interesting for someone to get out your way to check out in future.
Hopefully you can get it going a bit better.

Alway wear safety gauges when using gauges & charging refrigerant.

Leak testing can be carried out with soapy water, but not near electrical

[piezomot]

piezomot,
Seems to me system is short of refrigerant.
Would expect suction pressure of 58 to 85 psi depending on room temperature. The closer to 22-24 deg C room temperature could be 58psi or more.
You would normally want above 58 psi suction pressure, or above 0 deg C to prevent freezing the evaporator.
Make sure air filters are clean & good airflow.
Same with clean condenser, no build up of dirt on air on side of coil Dave.

Discharge pressure 250psi okay on a hot day.
Sometimes a liquid line sight glass can show if liquid line in full, which is what you want.
You may have a very small leak that could have taken years to lose , or something bigger, that will cause re-occurring problem.
Ideally leak should be found & fixed, which may not be an option for you.
Sometimes a small oil stain, dust on oily area could be where leak is.
Can only suggest you network with others in the area that may need repairs to help keep costs down etc& make it more interesting for someone to get out your way to check out in future.
Hopefully you can get it going a bit better.

Alway wear safety gauges when using gauges & charging refrigerant.

Leak testing can be carried out with soapy water, but not near electrical

Thank you for your prompt reply RANGER1. If you look at this picture: 16114

I was able to increase the suction pressure from 43 to 50 PSI, but this action inevitably leads to an increase in pressure on the red line, so it increased from 200 PSI to 225 PSI. I assume if I charge it more and increase the suction blue line pressure to 58 PSI then the red line pressure will be 250 PSI and if I go to 85 PSI on the suction blue line then I assume the red line pressure will be 350 PSI. Is it normal? What is the normal pressure for the red return line?
This video shows the blue line pressure 55 PSI and the red line pressure 145 PSI:
https://youtu.be/SUyN94Y39Ro?list=PL7XFU9Y6uohwdxUCNRohnCIFunBPAwjge
This video shows the blue line pressure 75 PSI and the red line pressure 150 PSI:

https://youtu.be/GlS8aAkUBT4?list=PL7XFU9Y6uohwdxUCNRohnCIFunBPAwjge&t=671
My question is- why my red line pressure is around 225 PSI when the blue line pressure is only 50 PSI?

[seanf]

Thank you for your prompt reply RANGER1. If you look at this picture: https://www.refrigeration-engineer.com/forums/attachment.php?attachmentid=16114&stc=1

I was able to increase the suction pressure from 43 to 50 PSI, but this action inevitably leads to an increase in pressure on the red line, so it increased from 200 PSI to 225 PSI. I assume if I charge it more and increase the suction blue line pressure to 58 PSI then the red line pressure will be 250 PSI and if I go to 85 PSI on the suction blue line then I assume the red line pressure will be 350 PSI. Is it normal? What is the normal pressure for the red return line?
This video shows the blue line pressure 55 PSI and the red line pressure 145 PSI:
https://youtu.be/SUyN94Y39Ro?list=PL7XFU9Y6uohwdxUCNRohnCIFunBPAwjge
This video shows the blue line pressure 75 PSI and the red line pressure 150 PSI:

https://youtu.be/GlS8aAkUBT4?list=PL7XFU9Y6uohwdxUCNRohnCIFunBPAwjge&t=671
My question is- why my red line pressure is around 225 PSI when the blue line pressure is only 50 PSI?

For the High side people normally add about 15 Deg C to the ambient temp to give them an idea of what running pressure to expect. So your ambient of 32 Deg C +15 gives 47 Deg C, R22 at 47 Deg C is about 248 psi.
Pressures above the expected value can indicate poor air flow or dirty condenser coil.
Best to do the checks Ranger has recommended before adding more gas.