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Originally Posted by Xringer
Questions? I've got a million of them and very little time before the snow
starts coming down!
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I think you're gonna do just fine. You've crossed every 'T' and dotted every 'i' that I know of...
Something you might do though, since you have so many new pieces of equipment, you probably already have a coil of copper tube left over from some previous project. You might want to fold and braze (or solder in this case) one end and put a 1/4" flare on the other, or better yet, if you can find one local, a 1/4" Schrader valve (standard refrigeration part), and do a couple practice pump downs on it, just to get the feel of the process.
I had already kludged together my first heat pump before I installed my Sanyo, so my confidence was fortified just a little.
If you decide to do this with a Schrader valve, the valve core is identical to a car tire valve, and has rubber seals. Make sure to remove the valve core before you solder or braze and do not re-install it until everything is cool to the touch.
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I've been mulling over in my mind what you said previously:
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Also read about using a micron gauge. One guy had three of them and they all gave different readings.
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Not quite sure what he meant by "they all gave different readings", but almost all of the micron gauges today have numerical digital readouts, but they have analog sensors, and there's going to be some variation there. Also, modern micron gauges have a glass bead sensor that can become fouled, but is easily cleaned.
I think that digital outputs can lead people to expect a level of absolute accuracy that may not be warranted. Digital gauges are popular because they have become cheaper to manufacture than analog in some cases, and they are usually easier to read.
One weakness of a numerical digital gauge is being able to convey the nature of variation of the system under measurement. Is there a rythmic swing in voltage, current or pressure? This could be important. If the settling time of the gauge is long, you might never get a sense of the nature of the variation.
Regarding micron gauges, this variation isn't so important, so a numerical readout is appropriate.
But if the person in you cite had three gauges and one read 300 microns, another read 335 microns and another read 400 microns, they're essentially telling him the same thing. If the spread was 70, 115 and 1500, that's a whole different story.
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Another fellow said they were a luxury that you really didn't need...
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I'll never forget the time I was in New Orleans, talking to a local Cajun guy who had just cooked up a great Etuffe. I asked him how he made it, and he said, "Well, you make you some roux, and fry you up some chicken and vegetables to your likin', and flavor it up 'til it tastes right." If I had grown up in Louisiana, and had eaten Cajun food all my life, that would have been enough information for me to make Etuffe. But since I hadn't, "...flavor it up 'til it tastes right", had no meaning to me.
So there's the possibility that after 20 years in the trade, you really don't need that luxury.
There's also the possiblity that his installations lasted past warrantee, but not much more.
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The manifold gauge set is primarily designed to give you information when about what's going on when you are charging a system. It will simultaniously read the pressure of the high side of the system and the low side of the system, and show you if there is abnormal variation happening. Their best accuracy is at mid-scale and they are designed so that the proper levels of charge pressure occur at mid scale.
But the manifold gauge set will not tell you if you've vacuumed low enough to allow for the removal of water. The accuracy is simply not there.
If you have a new pump, with fresh oil, you're probably ok. If your gauge, whether it is a single gauge or a manifold gauge set, is new and with good seals, you're probably ok. If your hoses don't leak, you're probably ok. If you've screwed your fittings down properly, you're probably ok.
But even with twenty years experience, unless you measure your vacuum with a gauge that is designed to measure deep vacuum, you really won't know for sure.
I installed my Sanyo without a micron gauge, I'm probably ok. But in fact, I'm not completely sure.
If I were doing it again, would I leave my micron gauge sitting in my tool box while I was installing a brand new mini-split heat pump?
I think you know the answer.
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...spend your money on a good manifold and a good pump and keep it good shape.
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My advice to you would be to get a good micron gauge, and a cheap (or used) manifold gauge, make a test setup and measure the gauge set to see just how good it is.
...but then, "I'm not an HVAC tecnician, in fact, I'm just barely a hacker."
Best regards,
-AC_Hacker
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