Hey thanks for watching in this video we're going to look at a line, isolation test. This is something that you would do on a split system when you're really struggling finding a leak, and you think that the leak might be occurring in the line set now keep in mind. You do not want to be wrong about this. You don't want to tell somebody that they need to do a line, isolation test when in turn it's something that you could have found by doing a more thorough leak detection.

So a lot of this process is going to focus on just making sure you get that part right, but sometimes you will have leaks in the line set, especially nowadays we're seeing a lot of the ductless line. Sets there's some sort of reaction going on between the copper and the insulation, some people think or maybe it's just the quality of the copper. But we are starting to see leaks occurring in line sets there or you could have a line set. Maybe if it's going underground for a portion, there might be something in the in the ground.

That's reacting with the copper, so it can certainly happen that line sets can leak. This process helps you prove whether or not that's the case, but as always make sure that you're doing things in the right order, so that you're not wasting time and so that you're not wasting your customers money step. One do leak check on the entire system to confirm. No leaks are present everywhere that you can get to.

You need to do a proper leak detection. This means that you have to carefully and slowly go through the system. If you have a system that had an enormous leak in it, that would be primarily done with a pressure test and you know just kind of listen. That would be the first step, but if you've got a small leak on a system, that's got refrigerant in it.

Maybe it's been recharged once or whatever the case may be. You go through and do an electronic leak detection and we suggest good quality leak, detectors we're showing a field piece leak detector here. The h10 from baccarat is a really good leak. Detector.

The stratus from inficon is one that we use and then we've been experimenting with ultrasonic leak. Detectors too. Those all can work really well, but you have to make sure you use them. You use them slowly, you're, not getting interference from other chemicals you're, not bumping them around you're, not sucking any water into the tips, and you also need to know how to maintain your leak detector properly, to ensure that it is working many times.

This step is what leads to people calling for a line, isolation test just because their leak detector is not working. If your elite detector's not working, then you need to know how to test it and maintain it rather than just saying some version of well. I think my leak detector's not working. You know you got to make sure that it is.

If you have a heat pump system, you can run the system in heat mode to increase pressure in the evaporator coil. In order to have maybe some smaller leaks show up. In many cases, obviously evaporative oils do tend to leak, because it is a corrosive environment. You have more water there, and so you tend to get more galvanic corrosion that occurs because of the presence of water.

If you are trying to prove whether or not an evaporator has a leak - and it may be very small - running a heat pump in heat mode for a little bit can can help don't ever over pressurize systems, because then you could actually cause a leak rather than Just finding the leak once you know that you cannot find the leak either outside or inside you don't have any signs of oil. You can't find anything obvious you haven't, you know, maybe you've done bubble tests and your caps and cores and everything else make sure to do all of that. First, if you still can't find anything now we're going to go into the stage of doing our line. Isolation now this is something that you need to do in accordance with your company's policies.

It's often something you're going to need to quote the customer, for so only do it if you absolutely cannot find the leak otherwise, and you have reason to believe that it could be in the line set. Also, you know in our market we have a lot of underground line. Sets so it'd be a good time to go ahead and dig up the chase on the outside and see if there's anywhere in between that condenser and the chase that it might be. So next you pump down the system.

Now you pump it down as best you can. A lot of compressors nowadays don't allow you to pump down to a real, deep vacuum, but it's still helpful because that way, you're trapping as much of the refrigerant in the condenser. As you can so that you're not potentially cross-contaminating that refrigerant by putting it into a recovery tank, many of us like to believe our recovery tanks are completely clean, but that's actually not the case. Generally.

They actually come with a lot of sludge in them. In many cases, so i prefer to try to pump down as much as we can and then you shut down both valves recover any residual. That's left, then you isolate the lines by cutting them near the evaporator coil and then pinching them off. I like to actually pinch off both sides and put a schrader core in the side on the evaporator side so that you can pressurize at this point the line set uh each line individually, and then you can also pressurize the evaporator coil.

Now you can pressure test both the refrigerant lines and the evaporator coil. I say you know to 300. Psi is what i say in this guide, but you have to follow on the evaporator coil. At least you got to follow the low side pressure test protocol on the high side.

You could actually go up to generally, you know even as high as 500 psi now, because you're only pressurizing your line set, you don't want to go really any higher than that, because you run the risk of actually pushing nitrogen through your service valves and contaminating your Refrigerant in the condenser, but you know 300 - is kind of a happy medium you're not going to ruin anything with 300 psi, and so that's why i listed here. But you know, as always, follow your manufacturer's guidelines on that. You do not want to over pressurize an evaporator coil and cause a leak when you are doing this pressure test again: you're separately testing the line set and the evaporator coil, and with this test you want to monitor it with a really fine instrument. This is where probes come in, really handy.

If you use something like your field piece, jawblink probes, it works nice because you can actually watch pressure drop over time. That's what we call delta p or change in pressure. You can use one probe on each and monitor those carefully now, while the system is under pressure, now would be a good time to go ahead into that condenser because it still has refrigerant in it and do a really thorough leak check inside that condenser just check Everything i mean you got nothing else to do anyway, while you're waiting on the pressure test. A lot of people ask how long well, you have to hold it long enough until you can figure out where the leak is at this point.

At this point, you've already done a lot of leak detection, so just keep letting it hold until you know where the leak is and continuing to leak detect inside the condenser is a really good thing to do at this point, you can also go ahead and clean. Your drain, you can do you know whatever else needs doing now, is a good time to go ahead and do it maintenance wise, while you're waiting to see that pressure drop at this point, once you find the leak you got ta rectify it. So obviously you know if it's an evaporator, coil or a condenser coil, something significant. Then that's going to have to be quoted in some cases you're going to find that it is the line set.

If it is the line set, then you're going to have to quote generally to rerun it, but i also like to try to figure out exactly where it occurred if possible. In florida we have a lot of underground lines. So the only way you're going to know is once you pull it out, but in many cases you can kind of figure out what caused it in our market. In many cases, it's because there's a pool nearby and maybe that pool water is running into the chase or maybe it's a water, softener and the salt water is running into the chase.

So it's always trying to figure out what the source of corrosion is. So that way, you don't just run the copper back in the same place. It was in before and then you're just gon na have this same issue all over again once you rectify it. Obviously, while you are brazing, you need to be flowing nitrogen.

You need to put a new filter dryer in some cases, that's going to mean cutting out the old one inside the condenser and of course, in that case, you probably should have done that before you bump down into the condenser, probably should have just recovered, but that's Something i could have mentioned at the beginning, but you do only want to have one liquid line dryer in in the line and i'll generally like to locate it inside near the indoor metering device in the liquid line, if at all possible, to prevent corrosion once you've Rectified the leak, whether that's running a new line set or fixing now go ahead and pressure test. Do another pressure test and bubble test. All of your joints, pull a vacuum down below 500 microns and then open the system for service. So those are all kind of your standard practices that you would do on a new install anyway line dryer bubble, testing pressure, testing, evacuation.

Those are all things you got to do just as regular course. Most importantly, here, though, is having a leak detector. You trust and knowing that you could not find the leaks before you go into the line, isolation test and then at that point the line. Isolation test is going to essentially prove that it is the lines that are leaking again.

The reason why this matters is because, in many cases replacing your refrigerant lines is an expensive, time-consuming, endeavor, and you need to make 100 sure that that's what it is, and that is what this line isolation test allows you to do, allows you to prove it and Then also just kind of allows you to prove that you don't also have a small leak in the evaporator. Coil that got missed just helps, helps prove that again, a lot of people ask how long the pressure test long enough in order to know i'm generally speaking, you're going to want to let it sit about an hour or plus um, to be sure that you only Have a leak in the lines or only in the evaporator coil before you proceed at this point, you do not want to get it wrong all right, thanks for watching. That is how to do a line. Isolation test, maybe some slight variations in your process.

If you have a different process, i'm always happy to hear it. You can go to hvacr, hvacrschool.com leave me a comment there and let me know what you think thanks for watching our video, if you enjoyed it and got something out of it, if you wouldn't mind hitting the thumbs up button to like the video subscribe to the Channel and click the notifications bell to be notified when new videos come out. Hvac school is far more than a youtube channel. You can find out more by going to hvacrschool.com, which is our website and hub for all of our content, including tech tips, videos, podcasts and so much more.

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