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  1. #1
    Join Date
    May 2010
    Location
    California
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    21

    Flowing N2 during brazing not important?

    I have a Lennox 13ACD with a Copeland Scroll in it that died at the 4 year mark and Lennox is being good about replacing the unit under warranty. The problem is this is not an isolated case, I've seen quite a few compressors die well before the 5 year mark in a few of our communities. It's usually related to the particular subcontractor that installed the system.

    I once read the quote "compressors don't die, they're murdered" and I'm beginning to think our sub contractor is the culprit. I talked to Emerson about performing a forensics on the compressor and they referred me to a distributor to have it shipped back to them. Here's where the N2 part comes in...

    I was talking to the distributor about all the issues I've noticed with our subcontractor over the years; Items like poor duct designs with abnormally high ESP, undercharging, overcharging, and no N2 flowing during the brazing process... he stopped me when I mentioned the nitrogen and said it's really not that big a deal on small residential installations.

    I've read through the entire thread dedicated to flowing N2 and I've also seen the YouTube video with the black crap (oxidation) coming out the end of the tube. I have a hard time believing that the lack of N2 is a non-issue, especially when every manufacturer clearly states using it in all of their installation guides.

    So... is N2 really a non-issue for "small residential installs" for you guys?

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,671
    Well......

    Given the other issues that yopu mentioned, I'd say that nitrogen is not AS important as proper system design, proper charging and setup.


    Then again, if you're the kind of guy that does good duct design, good setup and system testing, you're likely the kind of guy that purges with nitrogen when you braze.

    Kind of a package deal in my opinion.

  3. #3
    Join Date
    May 2010
    Location
    California
    Posts
    21
    I agree... In this particular case I'm almost sure it's the duct design but that's another story. I was just concerned that he dismissed flowing N2 so easily as a contributor.

  4. #4
    Join Date
    Jun 2009
    Location
    Albuquerque NM
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    2,485
    Yup, package deal is right.

    The first guys I had doing my install were doing really crappy work, including not flowing Nitrogen during brazing. I think it's sort of an indication of the overall quality of work someone does. After the first day I paid them what they quoted for the whole job, then "uninvited" them to come back to finish the job.

  5. #5
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
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    6,048
    that makes sense. Its not like we use hard drawn and have a fitting at every bend.

  6. #6
    Join Date
    Jun 2009
    Location
    Albuquerque NM
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    Quote Originally Posted by SBKold View Post
    that makes sense. Its not like we use hard drawn and have a fitting at every bend.
    Speaking of bends and fittings, my furnace & evap coil are in the garage and my condenser is on the roof. The first lineset installed by some "semi-pros" was poorly routed, would have had 4 splices, and had buckled bends in the line. It was completely removed. My new lineset makes a 90 at the coil and goes vertical up to the ceiling, then makes a 90 to go horizontal across the ceiling. There are two 45s to clear some vents, after which it makes a 90 to go straight up vertical through the roof. Once through the roof (about 3 feet), it makes another 90 to go horizontally about 10 feet over near the condenser, then a 45 to the condenser. There are no splices, all bends are large radius and smooth, and it's only brazed at the 2 ends. Nice work.

  7. #7
    Join Date
    Jun 2011
    Location
    Hammond,La.
    Posts
    1,176
    So is the guy brazing making quick proper work at it or is he one that nearly overheats every joint trying to get the job done? The longer the braze the more carbon that is deposited. Considering N2 is so cheap and it doesn't take any effort to flow a little for the braze that will ensure no carbon deposits.. I would question what other "not really needed" shortcuts they will decide is good. I would rather flow N2 and be sure none gets the best of me on a call back later because it got stuck in a metering device, screen, cap tube, etc. or some warranty guy finds signs of carbon and asks if I read the install instructions. Long shot, maybe but you never know lol
    "I am for doing good to the poor, but I differ in opinion of the means. I think the best way of doing good to the poor, is not making them easy in poverty, but leading or driving them out of it."
    Benjamin Franklin, 1766

  8. #8
    Join Date
    Jun 2011
    Location
    Houston area
    Posts
    1,493
    Quote Originally Posted by garya505 View Post
    .........There are no splices, all bends are large radius and smooth, and it's only brazed at the 2 ends. Nice work.
    Now that's impressive. Did you do it yourself Gary? Did they (or you) use solid Armaflex or split?

    Methinks, as Rcb stated, nitrogen is cheap and easy and there is not a compelling argument not use it.
    The picture in my avatar is of the Houston Ship Channel and was taken from my backyard. I like to sit outside and slap mosquitos while watching countless supertankers, barges and cargo ships of every shape and size carry all sorts of deadly toxins to and fro. It's really beautiful at times.....just don't eat the three eyed fish....

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  9. #9
    Join Date
    May 2011
    Location
    Canada
    Posts
    10
    I have to agree. If a tech isn't using N2 what other "shortcuts" are being done? (ie calculating your refrigerant, weighing, etc. vs "just opening the valve for a sec")

    Where I currently work, the bender is our best friend. Unless there are excessive lengths, our goal is only to be brazing four joints. However, I have been known to indulge in the occasional street 90's at the coil. Scandalous, I know. Haha

    My thought is with my helpers is that if you can't braze four joints without a leak by now, we have serious issues.

  10. #10
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    798
    not using nitrogen is kinda like not sterilizing the needle....

    maybe nothing will happen...maybe youll die from leperosy

  11. #11
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,989
    Quote Originally Posted by garya505 View Post
    Speaking of bends and fittings, my furnace & evap coil are in the garage and my condenser is on the roof. The first lineset installed by some "semi-pros" was poorly routed, would have had 4 splices, and had buckled bends in the line. It was completely removed. My new lineset makes a 90 at the coil and goes vertical up to the ceiling, then makes a 90 to go horizontal across the ceiling. There are two 45s to clear some vents, after which it makes a 90 to go straight up vertical through the roof. Once through the roof (about 3 feet), it makes another 90 to go horizontally about 10 feet over near the condenser, then a 45 to the condenser. There are no splices, all bends are large radius and smooth, and it's only brazed at the 2 ends. Nice work.
    The job U describe with the condenser/compressor way above the evaporator 'may' need to be specially piped to insure proper suction line oil return.

    It 'may' have needed a suction line trap at the outlet of the evaporator & reduced pipe diameter riser to increase suction velocity to help move the oil vertically along the pipe's inside wall area.

    Insufficient velocity would mean a compressor ending up with a lack of oil; also the evaporator can become oil logged...

    I would never install a two-stage compressor on that piping!

    Hope it somehow will keep functioning okay...
    Last edited by udarrell; 09-13-2011 at 10:58 PM. Reason: Wording...

  12. #12
    Join Date
    Jun 2009
    Location
    Albuquerque NM
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    2,485
    Quote Originally Posted by udarrell View Post
    The job U describe with the condenser/compressor way above the evaporator 'may' need to be specially piped to insure proper suction line oil return.

    It 'may' have needed a suction line trap at the outlet of the evaporator & reduced pipe diameter riser to increase suction velocity to help move the oil vertically along the pipe's inside wall area.

    Insufficient velocity would mean a compressor ending up with a lack of oil; also the evaporator can become oil logged...

    I would never install a two-stage compressor on that piping!

    Hope it somehow will keep functioning okay...
    The total rise is only about 7 feet.

  13. #13
    Join Date
    Jun 2009
    Location
    Nevada
    Posts
    139
    N2 flowing is absolutely a must for 410A systems. 410A, like R-12, has solvent characteristics that R-22 didn't (doesn't) have. A 410A system will polish all that stuff off the copper sometime in the first 10 minutes to 10 years... In others words, you don't know when it will strike. Even with R-22 systems I've seen them fail and found oxidized material floating free when it was opened up.

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