A learning tech, a question about an experiment

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I'm learning the trade, and have installed four or five residential systems under the eye of my instructor.
I've started buying some tools: A Robinaire 6cfm vacuum pump, a Robinaire thermistor gauge, some decent manifold gauges, a leak detector, basic hand tools, etc.
My dad decided to "take the risk", and let me install his new upgrade system. I'm going to do all the rough work, then let my instructor check it out before he charges it. But since this is "my" system, and not just a "job", I decided to try an experiment, and it's got me a little confused.
My instructor tells me to evacuate the system by "pulling it down as far a the pump will take it" then letting it pump for a couple of hours more. My new pump with new oil has taken every system down below 50 microns.
But the Rheem manuals say you only need to go down to 500 microns.
Well, I hooked up dad's system, and pumped it down. Then I shut off the manifold port valves, shut down the pump, disconnected the center hose, and put the thing to bed overnight with the manifold gauge still connected.
I wanted to see how well it would hold up overnight.
18 hours later, I reconnected the center hose to the pump, and pumped down the hose until I was below 50 microns again. After letting that 'age' a few minutes with the pump running, I opened the manifold valves, and the pressure came back up to somewhere between 275 and 400 microns (finest steps on my thermistor gauge).
It only took about three minutes to drop that back down below 50 microns.
Sorry for the long narrative, but here are the actual questions:
1) isn't the Rheem 500 micron recommendation kind of HIGH? Especially considering that my pump will reliably go below 50? 2) Did the pressure rise overnight by what is really a small amount because of diffusion through the rubber hoses, or does that 300-or-so micron rise in 18 hours indicate a leak? I can't disconnect the manifold gauge with a vacuum in the system without leaking in even more air than that, so I don't have another type of test I can do for pressure rise.
Thanks... just learning. Hope to have my certificate in about another 8 months.
LLoyd
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On Tue, 17 Apr 2007 07:29:22 -0400, "Lloyd E. Sponenburgh"

Nice story, Mr Homeowner doing your own install. Id suggest you check with your "instructor" and your "learning books" on the proper procedures. Then, work with an actual tech as an apprentice for a year or two and you should have all your questions answered. Bubba
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My "actual tech" couldn't answer the question for the reason that he never tried what I did. He doesn't spend 18 hours trying out an idea, because he earns his living doing it. FWIW, not one of my textbooks lists anything about passive pressure rise vs. time in an evacuated system.
And yes, DBCC actually offers the certification course, which is pretty poorly attended. And yes, there is a severe shortage of _qualified_ technicians in this part of Florida. I'd like to become one who actually understands my systems, instead of like the duct mechanic who answered above. I wouldn't be studying my ass off every night for ONE system, or shucking out what right now for me is big money on tools for ONE system; now would I? And since I can't buy refrigerant yet, wouldn't it all be kind of a waste?
Troll!
Does anybody besides this subhuman plenum crawler have a reasonable answer? Obviously, Bubba can't figure it out.
LLoyd
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Maybe if your didn't start off with a bunch of bullshit lies, you might get a more reasonable response.
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Which lie? That I'm studying for my universal certificate? Or that I have a local HVAC guy who's my friend AND my instructor? Or that I've installed several systems with him guiding? Or that I've already started building up my equipment list (including saving up for a recovery system)? Or that you can't hire one in ten AC people in this area who actually know what they're doing? Or that I'd like to be one that does know what I'm doing?
Which lie?
I guess this is like all newsgroups. You have to lurk for a while to know who the assholes are, and who the real experts are. You can't all be like these two.
LLoyd
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"Does anybody besides this subhuman plenum crawler have a reasonable answer? Obviously, Bubba can't figure it out.
LLoyd"
HAHAHAHAHA
Brilliant!
Great description, but there is no plenum his fat ass could fit in.
HAHA
I think if you can get a 50 micron vacuum you have nothing do worry about. I am always waiting for that pump on a R22 system. 500 microns is fine with me, never had a problem. 410A systems go a lot faster, I tripple evacuate them though. The POE oil absorbs moisture so quickly. I suspect your manifold guage is just introducing air to your vacuum, when you reconnect the manifold guage to the system. Your hoses shouldn't leak , maybe after a long long time. When I pressure test indoor and outdoor coils with 200PSI I come back in 3 days and either have a leak or the same pressure I left. I only lose the pressure my guages steal when I reconnect.
-Canadian Heat
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"DANgER" <"danger"@heat.com wrote in message

You really are clueless...
A new (since this is what he's asking about) R-22 or R-410 system pull down the same, as they both have a new line set and evaporator. (I know the *used* equipment you install includes the condenser when pulling a vacuum, but you really shouldn't be giving out advice on *used* equipment when the OP is asking about *new* equipment)
Also, if you think a triple evacuation gets the moisture out of an R-410 system (POE oil), you're also mistaken.
Every time you open your trap you show your incompetence!!
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On 17 Apr 2007 21:51:30 GMT, DANgER (danger< snipped-for-privacy@heat.com) wrote:

How many people do you need to tell your stupid ass about evacuating to an imaginary 50 micron level? Nearly impossible without lots of special equipment and time. Id like to hear you babble on about WHY a 410a system pumps down faster. This outta be good. Hold on. I gotta get some of that popcorn from Paul. Hoses shouldnt leak?? Okay, thats a good one DANgER. I guess you are using solid copper and flare nuts then on your gauges. Ever notice why most hoses say "Charging hose" and not "Evacuation hose"? I'll let you ponder that one for a bit. You pressure test a coil for 3 days??? How the hell do you get anything done. New gadget on the market, dunder head. Its called an electronic leak detector. Several work very well. Spend some of that so called fortune you have in your dirty laundry and buy one cheap ass. Oh and lastly you moron, triple evacuation is no longer necessary unless you are still one of the clueless brain dead dick heads that still uses a single stage vacuum pump. What? You dont know the difference between a single and dual stage vacuum pump? Go figure. You need a lesson in state of the art equipment bonehead. Oh well, just keep licking those windows and playing with your nuts. Bubba
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Still lost bubba. No clue what your talking about.
HAHA
-Canadian Heat
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On 18 Apr 2007 02:03:53 GMT, DANgER (danger< snipped-for-privacy@heat.com) wrote:

Nope, not a bit. Too bad you and your crack pipe have been working overtime for quite a while now. Bubba
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"Does anybody besides this subhuman plenum crawler have a reasonable answer? Obviously, Bubba can't figure it out.
LLoyd"
HAHAHAHAHA
Brilliant!
Great description, but there is no plenum his fat ass could fit in.
HAHA
I think if you can get a 50 micron vacuum you have nothing do worry about. I am always waiting for that pump on a R22 system. 500 microns is fine with me, never had a problem. 410A systems go a lot faster, I tripple evacuate them though. The POE oil absorbs moisture so quickly. I suspect your manifold guage is just introducing air to your vacuum, when you reconnect the manifold guage to the system. Your hoses shouldn't leak , maybe after a long long time. When I pressure test indoor and outdoor coils with 200PSI I come back in 3 days and either have a leak or the same pressure I left. I only lose the pressure my guages steal when I reconnect.
-Canadian Heat
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"DANgER" <"danger"@heat.com wrote in message

You really are clueless...
A new (since this is what he's asking about) R-22 or R-410 system pull down the same, as they both have a new line set and evaporator. (I know the *used* equipment you install includes the condenser when pulling a vacuum, but you really shouldn't be giving out advice on *used* equipment when the OP is asking about *new* equipment)
Also, if you think a triple evacuation gets the moisture out of an R-410 system (POE oil), you're also mistaken.
Every time you open your trap you show your incompetence!!
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With 410a on a *used* system, the best you can hope for is to install a new filter/drier, pull a 400 micron vacuum, and charge with new refrigerant.
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LOL ky reads and comprehends at bubba's grade level.
I said POE oil absorbs moisture quickly. Your just an idiot. I don't think anything... I know!
It's a given you install a new filter drier when you open up a 410A system. I thought we were talking about his vacuum loss?!?
HAHAHAHA you are a dumb bastard.
LOL I'm making the furnace cleaner gang look weak, this month! Where's bob the slob? What rock did he crawl under? You bitches need backup....tout suite ;)
HAHA
-Canadian Heat
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"DANgER" <"danger"@heat.com wrote in message

Please explain your following statement...
"500 microns is fine with me, never had a problem. 410A systems go a lot faster, I tripple evacuate them though."
R-410 evacuates faster *my ass*!!!!
You really need to stop your bullshit... we all no you don't know jack shit about HVAC/R systems.
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LOL ky reads and comprehends at bubba's grade level.
I said POE oil absorbs moisture quickly. Your just an idiot. I don't think anything... I know!
It's a given you install a new filter drier when you open up a 410A system. I thought we were talking about his vacuum loss?!?
HAHAHAHA you are a dumb bastard.
LOL I'm making the furnace cleaner gang look weak, this month! Where's bob the slob? What rock did he crawl under? You bitches need backup....tout suite ;)
HAHA
-Canadian Heat
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If you apologize to Bubba and Noon-Air.... I will answer your questions.
Otherwise, you can be our next little b*tch.
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As soon as they apologize for instantly calling me a liar without any knowledge of me, I'll consider it. My reaction to them was the same as it would be if any asshole walked up on the street and slapped me.
Several other people responded to my question in helpful ways.
To my eyes, Bubba and Noon-Air act like they're afraid someone who wants to learn the trade will take away their jobs. That smells so much like cowardice because of incompetence, it stinks.
If they lived here, there's not a chance in hell that could happen. We have HOT summers, lots of snow-bird imports who can't even mow their own lawns, and about half as many HVAC techs on the street as the market will bear. The average wait for an "emergency" service call in the summer is about two days. There's money to be made by good trouble-shooters who can actually FIX stuff, instead of automatically saying "You need a new unit". I plan to be one.
For those of you who helped, thanks. Especially, thanks for the clue that having the micron gauge near the pump gives a lower-than-true reading. That makes a lot of sense, but I never thought of it. I think I will hard-pipe a couple of old gauges into the unit. We won't let the charge into it until I say I'm done, and Ken says it passes muster. I figure we've got about two weeks before it starts getting hot, and my dad starts complaining.
LLoyd
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If you hadn't come waltzing in here misrepresenting yourself, you wouldn't have the credability problems you have now.

Sorry sport, when your a certified Master, then come talk to me about it. FWIW, it shouldn't take but a couple of hours(not the 8 months you said) of study to ace the universal test for your EPA card. All that EPA card means is that you can pass a written test, and your supposed to be able to responsibly handle refrigerants, it *DOESN"T* mean that you actually have a clue of what to *DO* with them. If it takes you 8+ months just to get an EPA card, I can't imagin how long its going to take you to actually get licensed for the trade. Here the minimum requirement is 2 years of college or tech school with a certificate of completion, *and* 4 years OJT under a Master...... along with a bunch of other stuff, and thats just to get approved to take the license exam.

You mean like being in south Mississippi??? FWIW, My business is based on service, and repair..... not replacement. Replacement is is nothing more than an added bonus. You, on the other hand, might want to take a chill pill before you go running off at the mouth again.

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I didn't misrepresent anything, and you're doing it again. My experience is liars always accuse other people of lying.
You're right about the refrigerant test. It's only 50 questions, which I could ace in a day. Ken says I have to be signed off by a master to take the test, or else I have to go to one of those boot camp schools in Orlando that do it in a week, which is costy. That's what he said will be in 8 months.
LLoyd
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