Nitrogen Facts and Tips

Bryan gives the Kalos techs a lesson about nitrogen to share some Facts and Tips. He also explains how it can be detrimental to HVAC systems AND how we can use it as a tool in the HVAC trade.
Nitrogen makes up about 78% of the air we breathe, but we want to keep it out of HVAC refrigerant lines because it is a non-condensable gas. It doesn't condense inside the HVAC system under normal conditions, so it takes up space, doesn't move through the system very well, and increases the head pressure. Nitrogen in the system also affects the pressure-temperature relationship.
However, nitrogen is also an inert gas, meaning that it doesn't react with other substances readily. As a result, it's a great medium for pressure testing and to displace oxygen while brazing.
Nitrogen also displaces water, which is highly reactive and can cause corrosion if left in the system. Nowadays, we also use highly hygroscopic POE and PVE oils, meaning that water is attracted to them; if POE oil comes into contact with water, hydrolysis occurs and produces acid.
In retrofit situations, we can actually reuse the line sets of systems that previously had mineral oil, as mineral oil and POE don't create a toxic mixture or anything. However, mineral oil systems fared a lot better with moisture, so we need to make sure that we remove oil and moisture from the line sets if we decide to reuse them. When we flush the lines, we typically use foam pigs and send them through the lines with nitrogen.
To prevent corrosion, we also purge nitrogen to displace any air or moisture in the lines, flow nitrogen while brazing to keep reactive fluids out of the lines, and pull a deep vacuum on the system. In our Central Florida market, we notice that corrosion is most common in places that run copper underground and irrigate with reclaimed water (which is high in chlorine and other reactive chemicals) or buildings with water softeners near the chase.
We also use nitrogen for the pressure test. When doing a pressure test, you can pressurize the system to the highest safe pressure. You put nitrogen in on the high side and watch the pressure on both the high and low sides rise. If the pressure on the low side stops rising, then you likely have a hard shutoff TXV. To do leak detection during a pressure test, the pressures need to be equalized. For best results, we also recommend using a bubble solution on joints, valves, and other common leak points so that you don't have to rely on the pressure test alone to find leaks.
When brazing, we need to know the difference between purging (or sweeping) and flowing nitrogen. Purging the lines requires you to send nitrogen through at a relatively high velocity to displace everything that's already in the lines, including oxygen. In the case of existing line sets, the goal of purging is to create turbulence that releases refrigerant and moisture from the system. Flowing nitrogen occurs AFTER you get all the air out, and it happens at a much lower velocity, only 2-5 standard cubic feet per hour.
A deep vacuum is what ensures that a system is clean, tight, and dry at the end of an installation. That's after nitrogen has been purged, flowed, and used for a pressure test.
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/.

[@jericosha2842]

Dude those animated clips are incredible. Great explanation of hard shut off txv. Makes sense to me now.

[@texture6]

Brian the HVAC Wizard 🧙

[@cromagnon305]

I'm an electrician and I like listening to this guy drop knowledge

[@mike-yp1uk]

Great content, the principals behind why we do what we do is awesome.

[@MrTom38ncalif]

Really appreciate your online learning lectures, professionalism, coupled with the fact that you bring an unbiased opinion to the table. Furthermore, youre abreast of current industry best practices which really help me stay up to date. While I am not a "ac guy" , i still enjoy increasing my knowledge base about the HVAC world.

[@edwincloudusa]

Great teacher, I have no clue about air conditioner in general, I'm not in that field, I'm a very busy man and I watched it all til the end.

[@SteveSmith-wm5vw]

I been in Ammonia refrigeration since 1998. And in refrigeration since 1990. Ammonia is a different animal but the same results (moving heat). I enjoy watching all your videos. Its a real good refresher over the years. Look forward for more of your videos

[@azdragoon72]

Excellent teacher!

[@rdenir]

Great video and a Master teacher..

[@jimsergi]

A nice clear sound also helps. nice job on this clip

[@condorman26]

I use these videos in training classes at our shop. Very informative

[@Skeetr86]

So, someone else teaches the class...

[@condorman26]

@@Skeetr86 some days. Yeah. These videos or interlearn or bluon. And somedays it's hands on. Your shop doesn't show videos?

[@jorgeaguila6774]

Outstanding as always tnx!!!

[@richardcascio660]

Excellent as usual thanks so much.

[@bikerbobcat]

Good refresher.

[@Stuart68505]

Helpful insights

[@cryptowill9025]

Great content

[@mikaelg5840]

Seems like the systems converted from r22 to r410 where line sets ran down into crawl space is where I find the most moisture contamination issues. It’s kinda like a large p-trap and not getting cleaned out enough before being reconnected to new equipment. Fortunately it’s rare, but when I do find them it’s usually when the line sets are ran thru crawls. Interesting video, learned something today!

[@michaelnash8435]

Triple evacuate those and pull down to 350 micron, then hold for 5 minutes and be sure you don't go over 500. Then you know you're dry and tight.

[@chrissucharzewski6047]

I love your lessons and I have learned much , thank you for spreading your wisdom. However @ 038 I believe you stated that nitrous oxide is combustible. That is not true. Sorry to be "that guy" but I have been involved with auto racing my whole life and @ 58 have had to correct many people on this. Sorry. Just an FYI

[@mod_incllc3235]

great info thanks

[@Jimmythetech]

Brian looks like you’ve been working out and your voice is deeper looks like the Sustanon 250 has been working well 🤙🏻

[@damnitdang]

Subscribed! Just found this channel from a KZbin add lol

[@J_Floress]

Currently having a nitrogen shortage here in Cali!!

[@HVACRTECH-83]

About the mineral oil, not sure why you think we don't use it anymore, sure,new systems don't have it but there's alot of systems out there that use it, compressor manufactures didn't change to some other type of oil for replacement 22 compressors and others, I still need to stock it for the equipment I service

[@ozziewelcome5612]

Good 👍

[@ethelryan257]

I enjoy Bryan's lessons. Some of the dudes in his class need to not be there, though....

[@rafaarroyo5438]

Thanks

[@dalvindersinghmanku8243]

Good one sir....sir can you please discribe can R32 will exchange R410a in our cooling systems....

[@anthonylosego]

R32 is A2L so you got some flammability. Meaning you can't put the flamey one in the non-flamey system. The R410A system will NEED to be redesigned to allow for R32. Sure... portable AC units don't have the same controls as a residential split system, but they are in a black box. House systems will need sensors and other stuff to use R32/R454b.

[@muhammadusamakhan5295]

God bless you

[@jroberts3428]

does nitrogen absorb moisture?

[@HVACRTECH-83]

It's best to use the low side design pressure for leak testing,usually 250psi on 410 systems, although I just replaced a Copeland 7.5 ton scroll this week and the literature said do not pressurize above 150psi for pressure testing, never seen that before and doesn't make much sense since you can run 150psi suction with a good load on it

[@lordjaashin]

Chinese and Japanese brand mini splits have a max pressure of 175 psi for low side lines. don't know why

[@boby115]

@@lordjaashin , The molecules of nitrogen are smaller than 99.9% of all refrigerants ( usually a lot smaller up to 1000 times smaller). This makes the nitrogen pass through a leak much easier, not requiring near the pressure. Excessive pressure of nitrogen can do a lot of bad things (pass through king valves, damage compressor valves or ports and the big one , cause more leaks than you had when you started) this is just to name a few. In my experience 150 pounds is more than enough and in most cases I can find a leak at 50 pounds where I start my initial pressure test.Bryan & @lordjaashin you two are definitely doing the right thing (Reading the manufacturers recommendations). Stay safe out there and regards from the St. Louis Metropolitan area (go Cardinals).

[@michaelnash8435]

Bob Y, there's some good advice in there, but if you're doing a pressure decay test, the higher the pressure, the higher the drop for a given leak. You'll find more micro bubblers at higher pressure. (Don't exceed maximum test pressure on the low side)

[@chancelindsey]

Questions on POE moisture contamination. You mentioned POE permanently changes state after absorbing moisture. Does pulling a deep vacuum not help restore the existing oil? What does the dryer actually do? Do the crystals absorb just moisture or do they absorb the moisture contaminated POE? Is there any chance for a system improperly installed that is suspected of having moisture to be saved before acid burnout? Or because the POE is in the compressor, with the "toxic goo", is the only way to salvage the rest of the system to replace the compressor? (Just thinking theory, obviously cost would be driving factor to run system to failure) Thank you for another great video.

[@abbe6305]

when i braze in a new compressor, scroll copeland, i need to have nitrogen, its it correct that i put nitro on low side and blow out on the high side? Becuse the compressor have a rewerse seal on high side in compressor and can damage the seal?. correct?

[@ralphlaurencastro]

Do you measure subcooling the same way if the unit has accumulator? Residential split with txv

[@michaelnash8435]

An accumulator is on the low side. If you're flooding back, you'll have saturated refrigerant. Normally, you'll have superheated. As far as the question goes, I think you meant a reciever. Subcooling should technically be measured at the condenser outlet but if you let the system stabilize it's normally close after the reciever. If there's a chance you're close, measure at the outlet.

[@rishicharan9248]

Can we flush or pressure test the system with co2

[@murkyturkey5238]

No never

[@davidlindgren7605]

When converting a system from R22 to R410a, is it necessary to clean the system with that special cleaner, or is flushing it thoroughly with nitrogen good enough? thank you

[@murkyturkey5238]

My boss has me flush with rx11 but In the past I have used only nitrogen. Time will tell but it’s best to flush it out. I’ve also heard the flush is bad for the system so idk lol everybody just does what they want. Nobody gives me consistent answers to problems

[@davidlindgren7605]

@@murkyturkey5238 what a dilemma! It should not be so difficult to getting correct answers. I''ve also heard flushing with cleaner will never get all the R22 out because some will still be held in tiny pockets in the coil. Is that correct or just a myth? Even if it leaves some behind, is it enough to interfere with the R410a performance?

[@w0lvez1]

If nitrogen doesn't absorb moisture. How does the rain form? 😮

[@timrob0420]

Another thing about leaks… if system has any leaks or will not hold a vaccum

[@casemodder89]

vacuum is MUCH weaker then pressure test. atmospheric is about 1 bar. 100% vacuum is 0 bar. but recommended pressure test on daikin AC heatpumps is 41bar ! so over 40 times stronger then just pulling a crude vacuum. keep that in mind !

[@timrob0420]

@@casemodder89 you pressure test to test brazes/integrity of flares. Vaccum will tell you if you have a leak though

[@casemodder89]

@@timrob0420 vacuum will not tell you if you have leaks that appear at 30 bar.

[@sammyg.3567]

So I think nitrogen is used to locate leaks only on flat or no refrigerant system.

[@972958]

I saw a line set today attached to really small line set how is that bad ?😅 I think it would increase the pressures and causes the system to work harder it was a R-22 24 year old condenser never maintained

[@darlinglinden2212]

wow thats terrible! I would change out the whole system and probably all duct work is falling apart as well

[@twolfe4295]

at what level of vacuum is all N2 removed?

[@Clamjammer]

1200

[@court2379]

So if you put a filter dryer inline, is it stronger than the oil at holding moisture? Any issues purging with argon?

[@michaelnash8435]

Argon would be fine, but nitrogen is cheaper.

[@court2379]

@@michaelnash8435 Not if you don't have a tank of nitrogen 😁

[@michaelnash8435]

I'd argue that if you don't have nitrogen, you shouldn't have an open system.

[@court2379]

@@michaelnash8435 That sounds like the crap the local plumbing and HVAC supply companies spout. And they don't receive my business.

[@jamminwrenches860]

So if one were to have strange fluctuations in an r22 system I could try to recover the charge properly evacuate then blow some off the recovery vapor port and expel the non condensables without having to replace the entire charge from expensive virgin r22. Waste a couple pounds trying or just replace the whole charge of around 6 lbs and be done on a hunch. I suspect the guy before me didn't pull a vacuum on it and there's no filter drier. Head pressures hunt constantly on a piston system.

[@timothy7819]

Yeah definitely air, once Hunting or pressure readings moving rapidly on discharge side, definitely air not being condensed, I would Vacuum and replace the r22, if you have an analog Guage you should see the needles moving very rapidly on the high-side

[@haxzal]

Why not use r11 to flush the system?

[@laurencel.7980]

what would be the max psi to nitro test copper lineset? I was told 250 psi but I know someone that says he uses close to 500 psi of nitrogen when nitro testing for a leak..

[@zack9912000]

500 is too high, all aluminum coils will pop at the joints.

[@laurencel.7980]

@@zack9912000 so what would be max. safe pressure to use?

[@murkyturkey5238]

350-400psi

[@murkyturkey5238]

500 is fine for r410a systems

[@arthernandez1363]

What would happen if by accident you flow nitrogen thru the compressor?

[@neilspieker2134]

We flow nitrogen through compressors when we replace them. You need to flow through it to prevent oxidization in the compressor. Or at least that’s what my boss says. I imagine that an excessive amount of nitrogen flow might toss some oil out of the compressor and that should be avoided before it’s brazed. But after I don’t think hurts anything. I could be wrong tho.

[@murkyturkey5238]

Just don’t push high pressure through the compressor so you don’t agitate the oil

[@DesiAnanth]

"you were too busy looking at your phone"... if it was here in India, teacher would've taken that phone long ago

[@MyBallzGotShocked]

Looking fit in this vid bro. Whats ur handicap

[@mvito39]

Liquid nitrogen to burn warts and skin tags..

[@johnbaptist7476]

You are amazing teacher for real . ❤ + 🕯 💜 ♾️ 👌🙏🙌👍👏󾓦✟✡✟󾓦 U S A . Godspeed 😇 👀

[@marriagepartnersministry5942]

Anyone else use co2 for purging and pressure testing? Co2 is cheaper than nitrogen, A tank lasts 10 times longer because the tank is filled with liquid co2 instead of gasseous nitrogen, and its still a shielding gas. Your thoughts???

[@shorty48shorty]

nos is an oxidizer non flammable. oxygen sure .

[@jasonjohnsonHVAC]

There is a medical grade nitrogen available...of course it is expensive

[@stefsam4583]

Nitrous oxide is not flammable. It is a stable oxidizer. Explosive yes, flammable, no.

[@AaronPowellvox]

These videos would be a lot more helpful in a more condensed version without the peanut gallerie’s dumb answers and comments.