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  1. #14
    Join Date
    Jun 2019
    Location
    Cape Carteret, NC
    Posts
    11
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    Thread Starter
    I have used TTT thanks to all of your recommendations. Wish I had known about the discount code. I'll try it next time (soon)

  2. #15
    Join Date
    May 2016
    Posts
    7
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    Well, copy and post to where it belongs, please leave a note as to where that is on this site. Been reading here 4 years and didn't want to jabber 'til I had something to contribute. "Permissions denied? My apologies. Thusly,

    Gauges v. Atmosphere (How to Deal with the Refrigerant side of the machine no more than twice, if you know how to diagnose). FOR BEGINNERS ONLY. Haha, just kidding.

    Based on what I’ve been walking up on, I’ve witnessed self-proclaimed 25 year techs demonstrate zero consciousness of this, up to and including not EVEN purging the line set on small critically charged systems (which still wouldn’t even be enough) so:

    It occurred to me while glaring at 2 brand new RTU installs (7.5 ton, 10 ton 410’s), a possible answer for why I’ve got so many 30+- year old units purring like kittens next to 2-5 year young installs running like sick horses. (More on what was wrong with the brand new units towards the end.).
    Culprits are:
    -POE Oil
    -Errbody been gauging up wrong.

    The mineral oil in the R-22 units is significantly less hygroscopic than the Polyol Ester Oil. Even if you pull a vac on your gauges before onset (opening the valves), the air between the valve on your gauge hose and the schrader port on the machine is enough to mess with the compressor performance on these hygroscopic oil units.

    Another aspect of gauging up matters much more on smaller capacity units than the larger:
    -The capacity of refrigerant held in the hoses/manifold.
    Just by adding refrigerant to my evacuated line set and manifold, I’ve seen anywhere from 2.25-4.15+ oz of R leave the tank, depending on ambient temp, refrigerant type, or if there were couplers, etc. This extra refrigerant will absolutely affect performance on smaller systems if you’re not keeping track of and accounting for it.

    Now I’m aware of low loss fittings, however as I’ve been told by the local parts house and after taking the fittings of the non-manifold gauge sets, it works as a check valve inward only so there’s no pulling a vac with them. I haven’t tried this myself, and would like input from anyone who has.

    So how do we gauge up to a system with complete and total confidence that we’re:
    -not adding atmosphere to the system,
    -recharging with the proper amount of refrigerant,
    -able to monitor system performance accurately once the unit is up and running?

    Please remember the overall philosophy is NO ATMOSPHERE CAN ENTER THE SYSTEM at any point or time, I’m not right there to hold your hand, but I’m tired of walking up on brand new broken machines. So is the customer. Hey manufacturer/engineer, if you’re reading, I’m guessing it’s cause you’re tired of it too. Field tech, maybe I’ll draw a map later if enough ask.

    a) Get you and yer equipment and yer bum up to the dam ruf.
    b) Recover refrigerant.
    c) Set fresh tank of R on scale. Tare.
    d) Connect mixing hose with fresh gaskets to a tee with one side to a NPR (nitrogen tank with regulator, and the other side with the valve on the hose open, to the fresh tank of R. The tank on the R is closed.
    e) Tee off one side to gauge manifold and the other side to vacuum sensor. Tee again to vacuum pump.
    f) Connect hoses on manifold to high and low sides accordingly, with valves on hoses closed.
    g) Pull vac on line set, if it looks good continue. If not, figure it out and fix it.
    h) Open valves on hoses, pull vacuum on system. I like 290 mic, correct me if that’s wrong. Please.
    i) Vac good? Close valve on hose valve to vac pump and follow manufacturer’s instructions for vac pump shutdown.
    j) Open valve on hose to tank of nitrogen, charge to manufacturer’s instructions (typically 100-150 psig) and let sit for 24 hrs minimum.
    k) Check on Nitrogen psig. If it has remained the same, vent the nitrogen and re-pull vac.
    l) Close valves on hoses at vac pump, then machine service ports.
    m) Open valve on tank of R. Note how much R went into just the line set. Account for this on charging and eventual de-gauging.
    n) Open hose valves to machine. I’ve usually seen them take most of the factory charge if not all without having to turn the machine on. Please correct me if I’m wrong, I have heard many experiences and theories on this, this makes the most sense to me and has let to best machine performance in the field as far as I can tell.
    o) Close high side on manifold. If charge was complete, hopefully you’ve already closed the valve to the fresh tank of R. If not leave open but keep close watch over the valve on the hose at the R, shouldn’t be but a moment for full charge, CLOSE IT.
    p) Double check your valves make sense and your vac pump is isolated annndd…..
    q) Disco switch let er’ rip!
    r) Oh wait… Was that tstat on a call for cooling? Dam I forgot. I should go check.
    s) Units running, monitor unit operation. I forgot to say at the beginning to have those manufacturer’s performance data sheets on hands first. Ooops, good luck if you got this far.
    t) FIGURE OUT WHAT THE HECK’S WRONG! (“Diagnosis”…)
    u) Turn off the machine before gauge removal. Be sure to use your recovery machine and tank to contain as much R as possible. Remember you already calculated excess like 130,000,000 steps ago.
    v) Advice: DO NOT think about how many times you had to go back to the parts house/your truck. Do not even think about your personal life for .0895 seconds or holy wow. Just don’t. Don’t. Yes, this is advice. Okay continuing.
    w) The roof is somewhere between 150— - 15 degrees. Quit whining.
    x) Manufacturers/Engineers: NONE of the techs are doing this by my experience. Please immediately switch to non-hygroscopic compressor oils. There is way too much job security. I am not seeing these issues on the older units.
    y) I love this industry and my career and these machines.
    z) Conclusion of scientific technical step by step manual.

    So you are full servicing the unit without ever having to move a hose or adjust a Schrader with the unit operating or exposed to atmosphere. Yaaaaaaay! Tents are on sale, lucky you.

    Long story short, it’s not sound logic to throw your gauges on a unit. Until you’ve verified no leaks, no contaminated oil, and proper charge you’re just ripping hair out of your head and trying to translate your gauges. It’s a dead end. Granted, I only do this if I am 100% sure it’s a refrigeration issue. I’d say at least 80% of the machines I walk up on are hurting because of environmental (install), electrical, or mechanical issues. Phew!

    Sure, if it is a refrigerant issue, you’ll have to do all of this twice, but at least you’ll know for sure and won’t be getting call after call on the same machine.

    **Now on what was wrong with the brand new RTU’s:
    7.5 ton R-410A RTU 460 V 3ph RTU
    Shipped: Circuit A: 3.3 lbs under
    B: 1.1 lbs under

    10 ton R-410A RTU 460V 3ph RTU
    Shipped: Circuit A: 2.6 lbs under
    B: 1.1 lbs under

    I know there wasn’t a leak on any of the 4 circuits because I was able to pull a 290 mic vac on all circuits. I did inform the manufacturer the units were shipped undercharged. They swore they shipped them charged full.
    If I’d have known they were shipped undercharged I’d have done the work on the ground when they shown up as opposed to dragging up my equipment up the flights of stairs then pulling them up the ladder to the 138 degree roof, that’s for sure. My company spent a lot of money and I had to explain why these brand new units were not functioning. Time for a post on the internet, HAHA!
    POINT: If they had actually shipped them full, and I could not identify a leak, and were short on charge, could it be an altitude issue (approx. 5280+-)

    THIS SPECIAL SUNSHINE ANGEL WOULD LIKE TO KNOW.

    Also wondering what your experience has been with the low loss adapters.

    Alright, rip at it and learn me something new!

  3. #16
    Join Date
    Jun 2019
    Location
    Cape Carteret, NC
    Posts
    11
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    Thread Starter
    WOW! I thought I was talking about tools

  4. #17
    Join Date
    May 2016
    Posts
    7
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    Gosh darn, my apologies, wanted to start a new thread, guess I have to make 7 comments first!

  5. #18
    Join Date
    May 2016
    Posts
    7
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    Tools is always a thing, knowing how to use them is another. Is has sure been a summer!

  6. #19
    Join Date
    Jun 2019
    Location
    Cape Carteret, NC
    Posts
    11
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    Thread Starter
    I did appreciate all you had to say. It’s obvious that you have a lot more experience than I do and I am always interested in learning. I just started out on my own doing service work. I haven’t run into anything too crazy yet.

  7. #20
    Join Date
    Feb 2016
    Location
    N'awlins!
    Posts
    141
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    No idea why my "like this post" button doesn't work but will wholeheartedly agree on purchasing from TruTech tools.
    Bought my personal tools from them, then set up my facility with an account.
    Prefer to shop locally when it makes sen$e, but TTT carries the full Viper line, of which many cannot be found locally.

  8. Likes TruTech-Bill liked this post
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