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purging with nitrogen during brazing - I don't

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hvac1993

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Discussion starter · #1 ·
I started installing HVAC units in 1993 and I have installed quite a few systems and made a bunch of repairs over the years. I have only purged nitrogen once or twice while brazing. I have worked with a lot of different techs over the years. I have never seen or heard of anyone actually brazing during a residential install or repair. (Other than guys online that I don't actually know.)

But, It seems everyone on forums seems to "always" purge with nitro during there installs and repairs. I think a lot of people claim to purge during brazing but, I think very very few actually do.

Anyway, I really think this whole purging during brazing is not needed. I sure don't seem to have any problems. I pull good vacuums, back sure I have good duct work, airflow, get sub-cooling and super heat dead on and I seem to have zero problems..


I am sure I will get attacked by all the online super techs.. Which is fine..
 
#3 ·
While I tend to agree with marc, I also tend to agree with the op. I cannot say that I have ever seen a system that had a failure due to oxide buildup. I am probably wrong but in my gut I feel it is like the whole cannot mix mineral and poe the world is coming to an end and the system will be ruined using the same gauges/hoses that was debunked many years later after 410a entered the residential realm. I'm probably just a hack for thinking this tho and will sit on the couch watching the conversation ensue.

'The more you know, the more you realize you don't know'
 
Discussion starter · #7 ·
I used to buy and use the RX 11 flush.. That was a complete waste of time and money..

Now I just purge my old lineset that can’t be replaced with nitrogen. But, I really don’t think that does much of anything.
 
#8 ·
Our installers don’t purge, and they burn the $#!t out of their joints with those turbo torchs.

My question to the op is, how do you know that anytime you warrantee an tXV on a system that it wasn’t due to lack of purging?

I know you must have them. I swap out around 10 a year that are less then 5 yr old. And I’m just one of the techs here. In my notes I always put down that it was due to lack of purging.
Although to be honest, I don’t know that for a fact.


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#13 ·
poppa said:
so you wash your hair, rinse and repeat? huh? just sayin
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dont you? i use a multi-purpose body wash, so it often gets done twice. not doing it wont make my hair fall out. not purging while brazing DOES create oxides and is a factor in future failures.
 
#14 ·
I'm sure you've seen what the OD looks like after brazing, the ID looks the same without nitro. Whether you've had callbacks caused by this or not, I'd say just play it safe and blow some nitro through your line-sets. You gotta get the nitro out for a pressure test right afterwards anyway, so why not...
 
#15 ·
RoK_HVAC said:
I'm sure you've seen what the OD looks like after brazing, the ID looks the same without nitro. Whether you've had callbacks caused by this or not, I'd say just play it safe and blow some nitro through your line-sets. You gotta get the nitro out for a pressure test right afterwards anyway, so why not...
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I’ve never understood why people don’t Use nitro. It adds a whole 10 minutes to the job. And it’s not like You’ll use enough nitrogen to make a difference in the cost of nitro either


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#16 ·
I do many many freeze-breaks with braze. Bang the break down, brush it until polished, and braze it over. I dont flow nitro on the plumbing pipes. When you turn the water on, the first burst of water is grey-black. And that's only from a 1/2" split. Ive learned to pull faucet aerators before turning on the water to flush. Ive plugged a few of them before.

Can you imagine what's floating around inside an AC system? Geez...
 
#18 ·
With 1000’s of RTUs built every year you can bet they purge with nitrogen while it is being built. They don’t want to deal with warranty claims due to oxidation and it makes it easier to get the vacuum done before charging, time spent on vacuum is time it’s not on a truck being delivered.


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#19 ·
I have cleaned enough crap out of TXV screens to know that brazing with nitrogen does make a difference. Not purging with N2 is just being lazy. It is not difficult to set up.

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#20 ·
Chev5372 said:
With 1000’s of RTUs built every year you can bet they purge with nitrogen while it is being built. They don’t want to deal with warranty claims due to oxidation and it makes it easier to get the vacuum done before charging, time spent on vacuum is time it’s not on a truck being delivered.


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Many years ago I was a piper for a very large equipment manufacturer (STULZ) and your exactly right. We Had to flow nitro while brazing or we had to cut out the stretch of pipe and redo with nitro. I didn’t understand why back then but it makes good sense now. I think it’s good the op has the balls to ask a question like this because “most” of us on here talk a pretty big talk. But with any online forum. No one can say if we’re actually doing what we’re saying. I can honestly say I flow nitro 99% of the time. The other 1% being where my jug ran out before I was done. It’s just how I was taught and it’s part of my routine. But the more I learn about it the more it’s reinforced in my head that it’s a good idea. I’ll never knock anyone for doing their work the way they do. Some of the best techs I know around here (md) don’t and I still respect them......
 
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