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  1. #1
    Join Date
    Feb 2004
    Location
    Pacific NW
    Posts
    563

    braze mini-split vs flare connections ?

    About to do first mini-split. Have done split units and always N2 fill and braze.

    Approach envisioned for mini-split (410A) is to cut the flare connections off and 15% Ag silphos braze, adding a bidirectional filter dryer and moisture indicator in the process.

    Opinions? Is this a wasted effort -- e.g. do mini-split flare connections have a good track record.
    Last flare I used on HP (R22) was on a 7.5T carrier HP 30 years ago and was not happy.

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,336
    The exv on minisplits are very small and the smallest piece of trash will make it malfunction. A drier is not recommended either, they are critical charge units and a drier can make it malfunction. best to use flares for mini splits and not risk screwing it up. Read and follow manufacture reccomended procedures IMO

  3. #3
    Join Date
    Jan 2011
    Location
    Boston, MA
    Posts
    459
    The few I have done I've always cut and flared them because thats what I've been told from a mr. slim class.

    They don't want any brazing due to risk of oxidation and contaminants because there is small strainers in the units. BUT if you flow nitro I don't see an issue but that's my 2 pennies.

  4. #4
    Join Date
    Jul 2009
    Location
    Columbia, MD
    Posts
    3,787
    DO NOT install a drier on the lines. if you braze and purge nitro you will be fine with your method.

    The company I'm at uses all hard pipe and fittings with these units. nitro purge is a most when brazing.

  5. #5
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,697
    have always used the flare fittings, only one failure i can remember was years ago on a sanyo unit when the flare nut split.

  6. #6
    Join Date
    Oct 2012
    Location
    Toronto, Ontario
    Posts
    67
    i have gone to a few Fujistu courses and they have said if you weld the warranty is voided

  7. #7
    Join Date
    May 2010
    Location
    Oxford, UK
    Posts
    336
    If its a wall mount i usually cut them off and braze them, then you've only got flares on the outdoor unit where its easy to check, the pipes are then easier to run through a wall or behind the unit without the bulk of the nuts etc. But it depends on the make, some units have little straines just after the flares so you can't cut these.

    No driers or sightglass, its an expansion line not a liquid line. Insulate both lines or it'll sweat. Measure the lineset as you go, and calculate the charge by the oz per foot/grams per meter chart, can't use subcool superheat with these.

    Best advice i had when starting to fit these is read the instruction before you start, they often bring out slightly different models or change the spec etc and it will catch you out otherwise.

  8. #8
    Join Date
    Nov 2011
    Location
    Texas
    Posts
    277
    we have a city multi going on now, 19 Ah and flares on everything

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    thats the main Bc controller, theres also a sub bc controller, Alot of flaring!! i feel like a pro at flaring now. make sure you have the right flare tool and oil your tool and copper while flaring. The less brazing you do the better, nito is a must if you have to. No driers or sight glasses. They dont want brazing bc the system dosent have diers and driersshouldnt be installed
    (((PEACE IS THAT BRIEF MOMENT IN HISTORY WHERE EVERYBODY STANDS AROUND RELOADING)))

  9. #9
    Join Date
    Dec 2007
    Posts
    4,668
    flares only, no flames on minis!!!!!!

    I have not seen that it voids warranty, but makes sense.

    they are trying to idiot proof the install.

    have not had a failed flare in our company, that I am aware of, in the approximately 400 units installed by us.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  10. #10
    Join Date
    Oct 2012
    Location
    Torrington CT
    Posts
    82
    i went to a city multi class they said to flare only no brazing they want a presser test up to 600 psi on there system and oil tool and copper

  11. #11
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,044
    Quote Originally Posted by mattt787 View Post
    i went to a city multi class they said to flare only no brazing they want a presser test up to 600 psi on there system and oil tool and copper
    We flare everything except on the branches that we run multiple heads on one branch. Where they tee off I flowed nitro and brazed them. Yes, pressure test at 600 psi for 24 hours. Then hold <500 microns for 24 hours.

    To the OP, make a good flare and it will be just as good as any braze joint. When people have trouble with flares, it is invariable due to a poorly made flare.

  12. #12
    Join Date
    Feb 2004
    Location
    Pacific NW
    Posts
    563
    Thanks guys, learned some things about mini-splits.
    Will stay with the flare and do the 600 psi N2 test and 24 hr vac also.

  13. #13
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,682
    At the recent Mitsubishi Diamond Contractor class we asked about brazing. The instructor said there is no objection to brazing provided proper procedures are followed - clean the joints, trickle nitrogen and use 15% silver content solder.
    However, he said flaring should not be a problem if a good flaring tool is used and a torque wrench is used for tightening the flare nuts. Also make sure to use the flare nuts that come on the equipment, NOT hardware store flare nuts that cannot withstand the pressure of R410-A.

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