How to Line Isolation Test an AC System
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- Опубліковано 7 лип 2024
- Bryan explains how to detect line set leaks and do a line isolation test in 9 steps. If you’re struggling to find a leak in a split system’s line set, you may consider performing a line isolation test as a last resort.
As we experience more and more copper corrosion and pinhole leaks in ductless line sets, thorough leak detection and line isolation tests will become even more valuable procedures.
First, you’ll want to perform a thorough leak check on the system. You may check for leaks with a pressure test. If there is refrigerant in the system, you will want to check for leaks with a quality electronic leak detector, such as the Bacharach H-10 (www.trutechtools.com/Bacharac...) or Fieldpiece DR82 (www.trutechtools.com/fieldpie.... No matter which leak detector you choose, use it slowly and maintain it properly.
You can run a heat pump in heat mode to increase pressure in the evaporator and make leak detection easier. Run the leak detector into the chase to check for leaks there. If you still can’t find a leak, then it may be time for a line isolation test.
Before doing the line isolation test, you’ll pump down the system by closing both service valves at the condenser. Crack the suction valve open about two turns. Make sure the system runs in cooling mode, and watch for the gauge pressure to drop about 10 PSI. Remember, you want to pump down as best as you can to avoid dealing with the possible cross-contamination of recovery. Tighten the suction line and pull the disconnect once you’ve finished.
Before you can install a service port on the liquid line side of the evaporator, you must isolate the evaporator. Then, you cut the copper line and pinch it off. If you install a Schrader core, you can pressurize the line set and the evaporator coil.
When you do your pressure test on the lines and evaporator coil, you should use nitrogen in accordance with the low-side pressure test protocol. Watch over the system and note any pressure drops over at least an hour. (We recommend using Fieldpiece Job Link probes: www.fieldpiece.com/product-ca...) While the system is under pressure, go back into the condenser with a leak detector and check it once more.
Once you find and fix the leak, it’s a good idea to identify the source of corrosion and develop measures to avoid letting the issue happen again. Then, you can release your nitrogen and begin closing up the system. Reattach the copper lines to the evaporator and change out your liquid line drier.
After you’ve put everything back in order, perform one more pressure test. Use a bubble solution to check your braze joints, too. We recommend using Big Blu from Refrigeration Technologies (www.refrigtech.com/big-blu/). Once all of those have been taken care of, pull your vacuum below 500 microns to perform a decay test. Then, you can open the system for service by opening the suction side valve and then the liquid side valve. You would perform many of these final procedures on new installs as well.
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Accutrack ultrasonic leak detector is the best
Heck yeah!!! Your 100% right!
Yep , found the smallest leaks . Work great for me
Started using the Accutrack ultrasonic about 25 years ago. Never looked back, best leak detector since the old GE. H10 B
It helps me to wet the area when I use my accutrack.
@@youngjohn5076mine must’ve been a dud it dosent show very small leaks only noticeable significant leaks where oil is present.
I realize I'm late watching this one, but would like to add a pro tip about it. In the event your isolation test is 24 hours or more, record the ambient temp. 300 PSI on 95 day will not be the same on a 75 day. Use the formula for gas laws P2= T2 (P1/T1)
Learned as always watching your videos. I'm fortunate that most of the linesets I encounter are run through a chase (through attic & down side of home) Get calls sometimes & system out of refrigerant (usually on a weekend) I always ask customers have you hung any pictures or blinds recently? Sure enough they sat yes & ask where & just flow nitrogen & unscrew what they screwed in & leak found. Just a reminder that the best tools we own are our eyes,ears,nose & mouths. Ask the right?'s & a lot of times will save time on not only chasing leaks. I also once found a line set leak in a wall that had a burnt staple next to l
I'm getting the ultrasonic tester. I see a lot of people having good results with it. Great video
Great info. Keep it coming. Thanks Bryan.
I like to watch your videos I'm always willing to learn plus this helps to sharpin my knowledge in the hvac field I know there is always something to learn education never stops here but I enjoy it.
Thank you for sharing.
I don't know if United still does the National refrigerant one shot recovery tank but that is a good option if you are worried about contaminated reusable cylinder. Basically it's a brand new disposable cylinder
H10 Pro is my leak detector. Works great
Yup, H10 could sniff out a fart in a wind storm.
Nice job and video
Sometimes with really small leaks I put it under an isolation test like that and come back in a few days to check. I’ve seen leaks as small as 20psig in one week using the nitrogen pressure temperature calculation.
Great video, I wouldn’t cut the line set, instead I will pump the system down and I hook vacuum pump ,after running for 30 mins ,check the gauges, to see if Still holds vacuum. If the pressure is rising you know there’s a leak in a coil or the line set. Plz correct me if I am wrong,
Suggestions for future videos:
Wines cooler are made different. It keeps the humidity. How come ?
2) Portable humidifier. How it is working ? Is it normal that it freeze?
3) Can you mix the refregerants ?
Thanks for your great works.
2) is deshumidifier, my mistake.
Wine coolers are made to retain high humidity in the box to not dry out the cork (shrinks and breaks the seal, oxidizes the wine).
Never mix any refrigerants.
I like the big blu leak detector. I have only had any luck with the electronic leak detectors indoors on small units since any wind at all makes them unreliable. Bubble soap don't lie!
Bryan, I also live in Florida where we run our AC mostly all year round, but on occasion YES we do sometimes turn on the heat. (laughter from the north heard here), well a few days after our 3 day dip in the low 40's and running the heat, I switched back to AC mode and a few days after that noticed AC issues, low on freon. Did running the Heat increase the pressue in the evaporator like you mention in your video and exacerbate the problem? I had a tech spend three ours looking for a leak and could not find one. He just charged the line with freon and it's been 4 days and all seems ok for now.
I use a test gauge that I use for my gas pressure tests. It shows increments of ten for one pound and shows the slightest leak with just 10-15 psi. Also using a mixture of Dawn soap and water in a spray bottle works better then the Blu spray, the bubbles are larger and easier to identify.
The first Service Mgr I ever had swore by a 50/50 mix of Dawn and water. Said it was the best leak detector ever made, but it had to be Dawn brand. That was 20 years ago.
@@iheartr2280 He was right, best soap ever for leak detection. Dawn is the magic. You can find gas leaks on low pressure just with a little brush so 100 psi is a piece of cake. My guys are convinced years ago. The AccuTrac is also a great option for medium to large leaks.
Don’t use dish soap. It’s corrosive. Most guys never wash it all the way off and it slowly eats the copper and aluminum. This is bad advice. There’s a reason big blue and it’s competitors were invented. It’s not caustic to the system.
@@donjohnson5172 I appreciate your comment but that isn't going to happen in the life of the equipment. No it's not bad advice. I'll stick to what I'm good at good luck.
supposedly from sources here on youtube Brian hvac school and Craig HVAC service tech and also other sources on the web you should never use dish soap on copper/aluminum as it will have a adverse reaction that will eat away the copper/aluminum over time and has been a reason for many leaks on A/C systems. Only Chemicals tested for A/C leak detection should be used.
MMLSO thanks for sharing this video and keep vlogging.
👍
Step # 1 is make sure you ACTUALLY have a leak rather than a refrigerant flow issue
Or an airflow issue
Fujitsu says 600 psi pressure test for mini split heat pump.
My company has been getting many copper evap coil leaks at circuit elbows,or just inside the end plate of a circuit. The plate rusts around the tube and somehow breeches the copper or aluminum tubes.. what boggles the brain, is there were no leaks at start up.
Sometimes I wonder if these coils been retagged from older specs?
Been running into the same thing.
coils are designed to fail. It is very profitable for the manufacture and supply houses. Very simple you can't have copper touching steel for the same reason when installing a new hot water heater you must always have a dielectric fitting between the coper and steel pipes of the water heater. The 2 metals placed together is highly corrosive. Brass can be used in place of a dielectric between steel and copper.
Why is nobody talking about how to change out a evaporator coil and identify leaks in package units??
I really don’t like telling people we’re going to have to do an isolation test. Try my dangdest to find with other means first.
thats alot of work for a bad TXV 😉
My least favorite part of the job is leak checking.
Try leak checking a whole rack on a supermarket. Its a hail mary.
We do a 24hr test
Me 2. It has to be right. Lol
Well if you have the right tools there is no real need to wait. A digital gauge that gives you pressure by the point you can see after 5 10 minutes if you lost anything
In 24 hours the temperature may be different the next day. Since temperature correlates to pressure your pressure readings could be very different when you go back and check. A digital gauge will tell you in 15 minutes if there's a leak or not. 24 hours might give you a false reading so I would honestly avoid it myself
@@homtanks6395 I would assume he checks the difference in temperature, there is a calculation for that.
In my opinion ,I think the manufacturers quality control sucks. I own AC unit that is over 25 years with no problems (knock on wood) but the stuff they make now is crap.
All this also depends on the age of the system.
🍺🍺🥃🍺🥃🍇🏌🏻♀️
Stay safe.
Retired (werk'n) keyboard super tech. Wear your safety glasses.
And steel toe boots....
Seems like a very long process and expensive for the client. Why not remove all the refrigerant then charge the system with nitrogen/hydrogen with electronic gauge connected. Easiest way to see if the system had a leak then can use a leak detector which senses the hydrogen.
If its a big system you can break it down and cap off pipework then test the exterior unit individually etc.
Potentially a big waste of time searching for a leak on a heat exchanger where there might not even be one or its too small to easily detect.
You perform an isolation test after you have done a previous leak check but the leak is so small you can not locate with conventional means. That is the process and when a isolation test will be performed.