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It is just gas pressure in the formula. It doesn't matter what gas it is.
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Originally Posted by
samgevas
Sounds like you recovered the charge, then put it on N2 overnight, but have not put a vacuum on it right?
What were/are the ambient temps there? When you started vs when you took the higher reading? Did you leave the gauge on it overnight?
My experience is usually pressure increases at this point are either due to either refer that was in oil, or part of the system was semi isolated/restricted so you thought it had pumped down or recovered to a lower pressure, but there is still a section with positive pressure.
Most minis don’t give you a service port on both lines. Not really a issue at install since the valves are all isolated in the outdoor unit with the factory charge, but trying to work on the hole system if the valve/s are closed pulling vacuums and pressure tests can get a little confusing.
I find It’s actually worse on a regular system with a TXV since the valve will respond to your pressures and temps even though the system is off. That’s why you should always pressurize through both ports if you can during a test. I’ve seen many a tech/installer think they had a leak when it was just their test charge taking it’s sweet time to equalize across a closed valve. Which from the point of view of the side your pressurizing through is seen as a pressure drop.
The above is mostly FYI, but I have found the opposite of this when recovering or vacuuming mini’s. A closed valve causes the side of the system you’re sucking on to drop well below your target when the other side is still high and needs a lot more time to get passed the restriction.
For the purposes of your pressure leak test, as long as it stabilizes and holds above 350psi for 30mins I’d call it good. On mini’s I give it as high as my current tank/regulator will take it, but at least 360. I’m a lot more confident in my brazing and soldering than in my “torque by feel” flares, so I’m a little more thorough on my leak tests with mini’s.
I’ve caught a lot of my flares leaking, some so slightly I’m not sure I’d have caught it with the lower pressures and more casual practices I employ on traditional systems. But to my knowledge, I’ve only ever had one flare leak after I left.
As long as the pressures didn’t drop and you insure that you pull and hold a good vacuum I wouldn’t be too overly concerned with the increase you’ve described.
On a mini with the outdoor unit(oil) in circuit I’m looking for less < 500 µm rising to no more then 1000 µm in 15mins once I blank off. I love evacuating and vacuum rigs, so this might be overkill, or unrealistic for you.
If my suggestion of the valve(s) being closed is correct you’ll pull down just fine, but it won’t stay down. If your micron gauge is a model that indicates whether your leaking or off gassing, it might say either, Because you’ll have both a steady increase from the gases squeezing passed the restriction as well as sporadic jumps from gases bubble working out of the oil. If the model unit your working on gas a recovery mode, this will hold the valve open. You can also unplug the comp and start the system while your vacuum is running. Most mini’s will cycle the valves across their whole rage at each start up. This could speed up you pull down a bit. On traditional systems cycling the Reversing Valve will help in a similar manner.
Sorry about the wall of text. I like to hear myself talk and when I get stuck on a toilet for a bit, well…
What ever happens come back and let us know.
Sent from my iPhone using Tapatalk
Did not put a vacuum on it, correct. I didn't have the vacuum gauge at the time. No, I did not leave the gauge on overnight. Temps were close, but didn't get actual temps when I left the system and when I returned to check them.
I'm adding an A31864 for a service port to the system for the reasons you mentioned. Tomorrow night, if things work out to get back to working on it. Will leave it in vacuum overnight to draw out as much refrigerant/contaminants as possible. Then another nitrogen charge and see what happens. Probably leave that in all day and do another deep vacuum the next night. After a triple evac like that it should be good to go.
I'm really thinking there's contaminants in there. I don't think the guy who did the initial setup service did it correctly. Issues with another system he installed required one of the big boys in town to come over and reset and replumb the system. It was red flagged by the city and all he did was turn the gas back on without fixing anything but the DIM.
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Originally Posted by
pecmsg
Need to send that link to my phone! Wish it was on one of my apps. Maybe it is, but I just don't see it.
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Originally Posted by
RedSafety
Need to send that link to my phone! Wish it was on one of my apps. Maybe it is, but I just don't see it.
Supposedly measure quick has a temperature compensated pressure test.
"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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HVAC School app has it under tools.
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Post Likes - 1 Likes, 0 Dislikes
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Originally Posted by
R600a
Supposedly measure quick has a temperature compensated pressure test.
It's in v2.0, just released today.
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Originally Posted by
vin lashon
It's in v2.0, just released today.
I think it was in the previous version also because hurst used it but I never bothered to find it myself.
"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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Originally Posted by
R600a
I think it was in the previous version also because hurst used it but I never bothered to find it myself.
Could be. Ditto on 'never bothered'. 2.0 has it up front in their new interface. You can still easily access 'classic', though.
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Post Likes - 1 Likes, 0 Dislikes
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Originally Posted by
vin lashon
Could be. Ditto on 'never bothered'. 2.0 has it up front in their new interface. You can still easily access 'classic', though.
I just downloaded 2.0 after you mentioned it and it looks pretty cool. I already see the nitrogen pressure test feature.
"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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You need to do a nitrogen purge before you do the pressure test. It’s always a great idea because it will help push out any remaining air/refrigerant/moisture.
If there’s moisture in the system when you do the pressure test you’re going to cause it to condense. Then when you pull a vacuum you run the risk of it freezing.
Sent from my iPhone using Tapatalk
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Originally Posted by
itsiceman
HVAC School app has it under tools.
Well then I already have it! Gotta take some time away from the slave driver to check out my apps.
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Post Likes - 1 Likes, 0 Dislikes
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Originally Posted by
itsiceman
It is just gas pressure in the formula. It doesn't matter what gas it is.
Then why put nitrogen in tires if the gas doesn't matter? Supposedly nitrogen filled tires don't change pressure summer to winter.
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Originally Posted by
RedSafety
Then why put nitrogen in tires if the gas doesn't matter? Supposedly nitrogen filled tires don't change pressure summer to winter.
They do change pressure with the temperature and all the data points to it being a scam or at least an exercise in futility. I put nitrogen in my tires because I haven't got around to buying an air compressor and I already have nitrogen.
"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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Post Likes - 1 Likes, 0 Dislikes
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Originally Posted by
RedSafety
Then why put nitrogen in tires if the gas doesn't matter? Supposedly nitrogen filled tires don't change pressure summer to winter.
Something about O2 wanting to pass thru the rubber to find equilibrium.
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Originally Posted by
RedSafety
Then why put nitrogen in tires if the gas doesn't matter? Supposedly nitrogen filled tires don't change pressure summer to winter.
https://www.consumerreports.org/tire...s-a6260003694/
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Originally Posted by
vin lashon
So it works and they didn't even use pure N2
Yeah I wouldn't pay for a shop to do it either.
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Originally Posted by
itsiceman
So it works and they didn't even use pure N2
Yeah I wouldn't pay for a shop to do it either.
I guess you can call that "works".
"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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Originally Posted by
R600a
I guess you can call that "works".
Those tires just sat presumably with no weight on them and far fewer warm/cool cycles than normal.
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Originally Posted by
itsiceman
Those tires just sat presumably with no weight on them and far fewer warm/cool cycles than normal.
I mean it had an effect but from all the testing I've read about I wouldn't say it works I would say it has an effect a very small percentage effect but for all intents and purposes is insignificant.
"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.