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Old R22 unit unusual pressures
Working on an old straight AC 2ton R22 unit. System has high head, low suction and constantly fluctuates. Arrived and found system running 65lo 325 hi. 15SC 45SH. 95F ambient. Delta T around 14-15F. I believe compressor shutting off on thermal was main reason for service call. Recovered some charge and now keeps head between 285-300 in 1 minute intervals. Suction fluctuates with head. No temp diff across drier. Piston was clean and clear. Replaced drier while system was open. Couldn’t pull a great vacuum as service valves leaked some refrigerant by. No money for virgin R22. Leaning on noncondesibles just can’t believe it’s a problem now after 25+ years of operation. Waiting on equipment to replace at owners request due to age anyways. Just curious what I could’ve missed during original service call. Thanks
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Probably non-condensables (air/nitrogen) in the system or mixed refrigerant, like someone topped off the unit with R422b (Nu22) or some other substitute. I know customer is saying no one has touched the unit in 25years, but all customers are usually liars or have mysterious short term memories.
When you were replacing the drier, could have recovered the refrigerant into a fresh recovery cylinder and checked the P/T to validate the condition of the refrigerant.
This is about all I can assist with in these open forums, are hands are tied by non-DIY rules, even in tech to tech arena.
If you are truly a technician, welcome to our forum, work on joining as a PRO member and we can really get down to the "nitty gritty".
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I read your profile. Get you post count up and we can help you in depth.
It's easy; just scroll through the open forums and answer some of the questions you find. Or just comment on them in at least modestly tech-speak.
What was the temperature difference between the condenser entering and leaving air?
Next time shut the system off and power just the condenser fan. Run it for fifteen minutes or so and then check the standing pressure against a P/T chart to get at least an idea what refrigerant(s) are in there. You could also recover all the refrigerant into an evacuated recovery cylinder. Give it 15 minutes to stabilize and then check the cylinder temperature against the cylinder pressure to chart the likely contents.
PHM
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Originally Posted by
nolift1
Working on an old straight AC 2ton R22 unit. System has high head, low suction and constantly fluctuates. Arrived and found system running 65lo 325 hi. 15SC 45SH. 95F ambient. Delta T around 14-15F. I believe compressor shutting off on thermal was main reason for service call. Recovered some charge and now keeps head between 285-300 in 1 minute intervals. Suction fluctuates with head. No temp diff across drier. Piston was clean and clear. Replaced drier while system was open. Couldn’t pull a great vacuum as service valves leaked some refrigerant by. No money for virgin R22. Leaning on noncondesibles just can’t believe it’s a problem now after 25+ years of operation. Waiting on equipment to replace at owners request due to age anyways. Just curious what I could’ve missed during original service call. Thanks
PHM
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
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[QUOTE=Poodle Head Mikey;26264787]I read your profile. Get you post count up and we can help you in depth.
It's easy; just scroll through the open forums and answer some of the questions you find. Or just comment on them in at least modestly tech-speak.
What was the temperature difference between the condenser entering and leaving air?
Next time shut the system off and power just the condenser fan. Run it for fifteen minutes or so and then check the standing pressure against a P/T chart to get at least an idea what refrigerant(s) are in there. You could also recover all the refrigerant into an evacuated recovery cylinder. Give it 15 minutes to stabilize and then check the cylinder temperature against the cylinder pressure to chart the likely contents.
Extremely high difference across condenser. 30-40 degrees
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In the face of that evidence why didn't you clean the condenser coil or examine other possibilities of air flow / heat exchange across the condenser coil?
PHM
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Me: [QUOTE=nolift1;26264789]
Originally Posted by
Poodle Head Mikey
. . . What was the temperature difference between the condenser entering and leaving air? . . .
You:
Extremely high difference across condenser. 30-40 degrees
PHM
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.
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I cleaned condenser but it had no dirt in it to start with. Fins are in good shape. Correct Fan blade and motor running correctly. Good airflow through coil out the top of condenser
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If that’s a double condenser it needs to be opened to clean it.
Condenser fan amps ratting and running?
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Single stack condenser. RLA 1.7 running 1.4.
Huge load in the space it’s a hair salon. That’s very busy. I’m sure when I left it would run all day but probably freeze at night. Vapor saturation at 95ambient and 300 head was around 39F
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Fluctuations = non condensibles...
No option other than to replace the refrigerant... or the system.
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
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Note your ra and suction line temp is practically the same.
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Hair salon!
Unit plugged with hair spray. Squirrel cage, evaporator. In the past unit overcharged to compensate.
Clean
Clean
Clean.
Every 2 - 3 months!
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Had removed the piston .. I would hope he looked at the Evap while standing there
Tell your Cat I said "Psst Psst Psst"
It seems like everywhere I go the AC is broken
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Evap was clean as it could be. High superheat with low vsat didn’t look like an evaporator airflow problem to me
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Originally Posted by
nolift1
Evap was clean as it could be. High superheat with low vsat didn’t look like an evaporator airflow problem to me
So if you checked the Piston did you check the strainer before the Piston if one was present? I find those clogged frequently.
"Is this before or after you fired the parts cannon at it?" - senior tech
I'm tired of these mediocre "semi flammable" refrigerants. If we're going to do it let's do it right.
Unless we change direction we are likely to end up where we are going.
"It's not new, it's better than new!" Maru.
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No strainer. Had a piston style I’ve never seen before. Don’t remember the size but it was clean and I oiled it. Liquid line had a flare nut onto coil. Piston itself was huge compared to new styles. Never seen one like that
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Originally Posted by
nolift1
No strainer. Had a piston style I’ve never seen before. Don’t remember the size but it was clean and I oiled it. Liquid line had a flare nut onto coil. Piston itself was huge compared to new styles. Never seen one like that
Did the piston look like a short piece of brass tubing with threads on both ends???
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
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No. Resembled a newer piston just way bigger. Couldn’t find one online anywhere
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Originally Posted by
nolift1
No strainer. Had a piston style I’ve never seen before. Don’t remember the size but it was clean and I oiled it. Liquid line had a flare nut onto coil. Piston itself was huge compared to new styles. Never seen one like that
You can’t see the film hair spray leaves!
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