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  1. #14
    twilli3967 thanks for the thorough explanation, now I know why. Thanks for everyone's input, except for drcustom's

    Drcustom, I am not sure what you are trying to communicate to me by the statement "Doubt he needs you to tell him if they're reputable." Please clarify. It does not make any sense.

    Thanks


  2. #15
    Join Date
    Apr 2004
    Posts
    420

    HI TOYOTA tech

    Originally posted by toyotatech
    twilli3967 thanks for the thorough explanation, now I know why. Thanks for everyone's input, except for drcustom's

    Drcustom, I am not sure what you are trying to communicate to me by the statement "Doubt he needs you to tell him if they're reputable." Please clarify. It does not make any sense.

    Thanks

    What happened was I started answering, backspaced through it all and said screw it. Try the search mechanism next time before asking. Brazing with oxy/acet, air/acet. should never be done without flowing nitro through the lines. But you knew that already, either from working on cars a/c or from reading the thousands of posts regarding it's necessity. This is such a basic concept that ANY company worth it's sand will do this when installing lines. In 16 years, I have never seen it done without it. Is there really a geographical island left within the US where it's impossible to find a reputable company? Usually it's a question of going with a low bid and then standing over a cheap hack's shoulder telling him his shortcomings--trying to make up for his low-cost-low-knowledge approach--with your supplemented rudimentary factoids like the one posed by your initial question. Go with a reputable company and you can sit on your couch sipping a beer as cool dry air wafts throughout your house. Nitro pfftt. That's why you hired someone. When I have a mechanic work on my clutch, I don't need to know how tight the nuts on a bell housing should be. I go with a past-history, referred mechanic and have never been sorry. Of course...it's never the cheapest. So go ahead and post now how you've tons of bids, carefully selected the mid-cost one and that this response it totally outrageous. Should've let this one die....

  3. #16
    Join Date
    Sep 2004
    Posts
    654
    If a line set were silver soldered instead of brazed, would that preclude the nitrogen purge all together? We have silver-soldered many lines throughout the years and never one problem to date.


  4. #17
    Join Date
    May 2004
    Posts
    12,285
    Originally posted by casturbo
    If a line set were silver soldered instead of brazed, would that preclude the nitrogen purge all together? We have silver-soldered many lines throughout the years and never one problem to date.

    The way I understand it is anytime you put heat of over 500 degrees you will cause carbon flakes inside of copper unless you flow nitrogen.

    People that don't use it would be smart to install a filter just before the metering device.


  5. #18
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Without the nitrogen for brazing or any high temp solder,you will likely have problems,though you may not SEE them.


  6. #19
    Join Date
    Jan 2005
    Posts
    109
    Question....isn't todays solder strong enough to use on AC system? I can see brazing 2 different type metals but is it necessary to braze copper tubing? Not being a smart a@@,just want to hear your opinion.

  7. #20
    Join Date
    Apr 2004
    Posts
    420
    I have a buddy at another outfit who swears by #8 silver bearing solder with which he uses a regular small propane or MAPP tank with. That is, he only brazes in new compressors and the like, using the solder for refrigerant runs on residential splits. Claims he never ever had a leak nor a complaint from a disgruntled homeowner seeking recompense for a leak repair. For me the manufacturers' specs spell it out perfectly clear in every I & O I've read: braze with nitro flow.

  8. #21
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    Originally posted by oilman52
    Question....isn't todays solder strong enough to use on AC system? I can see brazing 2 different type metals but is it necessary to braze copper tubing? Not being a smart a@@,just want to hear your opinion.
    Refrigerant lines are subject to conditions that water pipes aren't, for the most part. Rapid changes in temperature and pressure, and vibration. Therefore, the high strength of brazed fittings is best. I've seen soft solder used on refrigerant lines fail badly. I've also busted loose more than one water pipe that had a marginal soft solder joint...a wonder it didn't break on its own long ago.
    I also would be leery of slapping flux onto lines that are supposed to be as free from contaminants as possible on the inside surfaces.

    The last reason is why nitrogen is flowed during brazing operations. It minimizes oxidation of the inside copper pipe face when it is heated.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  9. #22
    Join Date
    Jan 2005
    Posts
    109
    You let nitrogen flow thru the lines as you braze. Do you let it trickle thru or do you let the nitrogen really flow? When you close the system up on the last braze,is the amount of nitrogen in the lines enough to stop flaking?

  10. #23
    Join Date
    Jan 2005
    Posts
    109
    I have used solder(silverbrite) in the past and haven't had any complaints. Old timer told me the old solder didn't have enough silver content or strength.

  11. #24
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    The mere presence of nitrogen or any inert gas is enough to prevent oxidation. It hardly needs to be flowing at all. Just enough inert gas to displace the oxygen will do the job.
    There is nothing more frightful than ignorance in action....Mark Twain

  12. #25
    Join Date
    Jan 2005
    Posts
    109
    So HvacPro I could close the whole system up and trhen braze as long as I have nitrogen in the lines? You guys might be saving me some call backs.

  13. #26
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    Nitrogen is usually setup to "flow" through the lines. Otherwise, there is no way to tell if all the lines are subjected to nitrogen and not air. A very, very small amount needs to flow out of the system. I usually connect the tank to the vapor line at the outdoor section and pressurize it so that it very slowly comes out of the liquid line service valve with the shrader removed. Too much pressure and the nitrogen will blow the liquified brazing material out of the joint during brazing and create a leak. Flowing into vapor line allows the nitrogen to bypass the indoor metering device so that you don't have backpressure building while brazing. I also allow it to flow until the joints cool down. AC systems love nitrogen. It also speeds up the evacuation process as nitrogen is a good drying agent.
    There is nothing more frightful than ignorance in action....Mark Twain

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