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  1. #14
    Join Date
    Feb 2004
    Basically, you pressure test to check for leaks from inside out. Think of a nail in your copper line, as you pull a vacuum the nail sucks in and makes a good seal. As soon as you put pressure on it, it pops out and causes a leak.

  2. #15
    Join Date
    May 2010
    Oxford, UK
    Quote Originally Posted by DelBoy2 View Post
    Sorry if this sounds stupid, but how do I make sure the EEV is open, or is it model specific? I have fitted many of these, but don't (yet!) have much experience of their inner workings.
    Good question! Its model specific, i've not had to do it on any of the mini splits we have fitted but just know it is something to be aware of should i need to pressure test the outdoor unit for a leak.

    We did a Samsung vrf and on that you can enter a code in the outdoor unit board for pressure testing and vacuuming if needed. A call to the manufacturers or wholesalers technical department should clear up questions you have as to if it is necessary for the equipment you are working on.

  3. #16
    Join Date
    Jul 2011
    Quote Originally Posted by DelBoy2 View Post
    I understand that pressure testing is more for the joints, as it's not so likely (although not impossible) that the pipes or inside unit is damaged. I guess the pipes could be crushed and have got weakened or something. Anyway, I've been told by many different guys that the most common leak point is the flare joints - either badly made or overtightened. I have also come across some really cheap quality pipe that is harder to make a decent joint on. So that's mainly why I test it, to test my own joints! I use a torque wrench on them, which is fine most of the time but not foolproof; once or twice I have come across flare fittings that got really tight without actually tightening the flare properly and still leaked.

    pipes and units are generally covered by their manufacturers' quality certificates, and if we look strictly formally, in the moment you suspect they are exposed to mechanical damage, they are not within warranty anyhow, neither you can restore it by testing.

    i mean if you have any evidence that your copper pipes are mechanically damaged, you ought to replace them, pressure testing itself, even if it passes, is not legally sufficient in number of countries i worked in.

    i was mainly referring to small systems where often there is no adequate testing port provided, and you should have to make one, which is becoming senseless if you do not have any other brazed joint. for larger system, the above mentioned procedures apply where i would always look into manufacturers recommendations, most of manufacturers i work with have detailed testing procedures within their installation manuals.

  4. #17
    Join Date
    Mar 2013

    The Rise of the Microns :)

    Hi again. I'm reviving this thread to ask about experiences with the micron gauge after switching off the vacuum pump. I watched a Yellowjacket instructional video that said it's 'normal' for the microns to start to rise after switching off the pump, but that if it rises fast or gets back up to atmosphere you have a leak. It didn't go any further on the subject though.

    Assuming you've pressure tested with nitrogen and are happy that the dial hasn't moved in, say, 30 minutes, how long do you all leave the pump standing to make sure the vacuum stays? How long do you allow for it to settle and 'find its place'? If the digital gauge creeps up really slowly, like the smallest measurement unit (we use mBars) in several minutes, do you literally leave it long enough to know that it's stopped creeping up, even if it takes ages?

    Many guys here say they can fit a split system in 4 or 5 hours, start to finish including drilling through the wall. That must mean either they're cutting corners or I'm doing something wrong...

    Last edited by DelBoy2; 04-28-2013 at 05:06 PM. Reason: Added video link

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