Vacuum taking a long time to stop dropping
Hey guys
Just wanted to check something with someone with more experience than myself...
Did a dual zone mini split install yesterday. Lines are 11 and 22 feet approximately.
Pulled a vacuum down to 240 microns, locked off the ball valve (Appion valve core removal tool) and the pressure continued to VERY slowly rise for a good 30-40 minutes, up to mid 300's..
Tried vacuuming several times in the end, and on the last one left it longer. It went from 240 to 360 in the first 40-45 minutes, and then stayed solid at 360 for a further 25 minutes. So finished the job.
But I've not experienced such a slow rise before, and taking so long to finally settle.
Is this fairly common, anyone else here experienced similar?
Thank you!
Comments
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New equipment and line set
holding at 300 is fine.
Holding at 500 is fine
Holding at 1000 is fine
1 -
moisture is evaporating.
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Moisture evaporating would be in the 1500 + range
2 -
Sounds fine to me. If it was moisture you would have a higher reading.
1 -
What's the longest period of time that's typical for the pressure to stop rising and lock in?
Is 45 minutes unusual/particularly long?
0 -
10 or 15 it should stabilize
While pulling the vacuum I concentrate on the electrical, covers, straps plenty of things to still do.
1 -
Yes, this is precisely what I've found in the past too. Sub 20 minutes to stabilize.
Should I have any concerns that this one took around 45 minutes?
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Did it stop below 1000…………….then NO
1 -
Yes, it stopped at 360 which was great.
I guess the only thing that concerned me was watching it rise for 45 minutes, a rise of 10 microns every approx 8 minutes. I left it 25 minutes locked on 360 microns, just concerned if I'd have waited longer it may have risen again?0 -
if there’s moisture in the line set then it will slowly and continually rise to above 1000 µm
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So after stabilizing for 25 minutes this would have been very unlikely in my case?
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So if it were any kind of physical leak, the rise would have been much higher\quicker?
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YUP
Actually, you wouldn't have gotten that low to begin with if there was a leak.
1 -
Awesome, that's what I thought and a big thank you for confirming. Will put my mind at rest, lol 😊
Like I mentioned on the first post, really wanted to get the opinion of people with more experience than myself, and got precisely that.
Great forum, thank you everyone! 👍️
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maybe it is something other than water evaporating.
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What makes you say that out of interest? That it took 45 minutes to stabilize? What time do you usually expect for stabilization?
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i'm not very experienced with evacuating systems with a micron gauge but oils and solvents and things like that will also evaporate and will have different vapor pressures than water.
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Yes, mositure was covered by pecmsg (above). Oils and solvents, I think unlikely as it was all brand new lines fitted with protective end caps to keep contaminants out. But possible I suppose?
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maybe contaminants leftover from manufacturing or not the best quality refrigeration oil from the factory? I guess the compressor was isolated so the factory oil shouldn't be involved.
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Yes, compressor was isolated. Not sure on the others, but anything is possible I guess.
0
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