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Sweating a coupling from the inside

mikemac52
mikemac52 Member Posts: 49
in THE MAIN WALL

replacing a hydronic baseboard unit and need to raise the vertical 3/4 feed pipe coming through the ceramic tile floor.

after trimming back the riser to match the element height, the coupling will clear the tile floor by 1/8 of an inch.

Im not confident enough in my skills to sweat this without being able to look at the joint.

If I sweat the coupling to the riser first, do you think it possible to feed the solder to the inside of the coupling?

A propress coupling is too long.

IMG_6425.jpeg

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Comments

  • Grallert
    Grallert Member Posts: 961

    The solder will go where the flux is on the copper and yes you can solder from the inside. If the joint is clean you should have no problem. Good luck.

    Miss Hall's School service mechanic, greenhouse manager, teacher, dog walker and designated driver

  • Ironman
    Ironman Member Posts: 7,715

    Is there access from below? Will the pipe give where you can pull it up?

    You say that you’re not confident in your skills, so I’m not confident enough to tell you to try that.

    Do you have a swaging tool where you could expand the riser and not use a coupling? If you could get access to a hydraulic one, you would need to soften (aneal) the pipe first by heating it red hot and then allowing it to cool slowly.

    Another option would be to use a compression coupling.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    mattmia2
  • Intplm.
    Intplm. Member Posts: 2,620

    If you must do it the way you describe with no access from below, go for it. Take your time heat it up slowly and solder from the inside to catch the lower portion of the coupling, then while you are working insert your pipe to the upper portion and solder that too.

    Heres a thought.

    If you are allowed to use 50/50 solder in your area maybe use that. It might make it easier. I believe it's okay to use on heating systems and not on potable water piping.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,707

    If it is first floor with basement access just cut the pipe off under the floor and replace it with a longer piece.

  • DCContrarian
    DCContrarian Member Posts: 1,117

    I would heat it from the outside and apply solder from the outside, 1/8" is enough. I would watch from the inside to see when the solder starts filling the gap. A good light would be very useful. Solder will flow toward the heat, even up. So I'd be heating from above.

    I'd have the next piece ready to go so I could put it together and keep soldering without letting it cool down.

  • HomerJSmith
    HomerJSmith Member Posts: 2,640
    edited August 2024

    I'm a little confused by your pic. You are using a standard 3/4" coupling about 1-3/4" long with a stop. If so, you can easily solder from inside the fitting as you are going down into the fitting 3/4". Make sure that the riser pipe is sanded perfectly clean and the inside of the coupling is sanded perfectly clean. I recommend Oatey Tinning Flux #95 that you can get at home depot. Put the flux on the pipe and the fitting that is going on the pipe. Unroll about 5" of solder, I recommend Canfield Watersafe silver solder, but Oatey's will work.

    Heat the center of the fitting on the outside and feed 3/4" length of solder to the opposite side from the flame at the inside joint. Don't over feed the solder into the joint. You are ready to apply the solder when the flux begins to bubble and drys up.

    Let it cool and clean the rest of the coupling joint as before, and as before flux and add the pipe and heat, solder normally. Are you saying that the stop in the coupling is at that black mark on the pipe? If so, you probably have to remove some of the concrete so that you can sand the pipe. If you could go underneath and push the pipe 3/4" up to sand that would be great.

  • mattmia2
    mattmia2 Member Posts: 12,608

    flare? compression?

  • Amovida
    Amovida Member Posts: 28
    edited August 2024

    Not sure I understand everything that is happening here but why not delicately recut the riser pipe at the floor height with an oscillating tool. You could get a nice even cut by pressing the blade against the floor and using it as a guide. You would have to hold the pipe so the oscillating motion could do its job.Would your 3/4 coupling not then sit higher above the floor allowing you to sand the pipe from above and debur the inside from below before putting on your coupling. The upper solder joint on the coupling should now sit 3/4” above the floor. Again sorry if I am not fully understanding all the aspects here. Good luck!

  • Big Ed_4
    Big Ed_4 Member Posts: 3,193

    From the photo , You will need to chip away the slab and expose the pipe before sweating . To avoid the slab sucking up the temperature and cement blowing up in your face . A vented tee is also needed on upward loops to release pressure…..Blowing out any trapped water is needed , boiling It out steams out the flux … Good Luck

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  • HVACNUT
    HVACNUT Member Posts: 6,747

    Sweating a coupling from the inside

    mikemac52

    You don't heat the joint, you heat the fitting. As long as it's a snug fit, the solder will pull in. I don't see the need to sweat the inside. Sweating from the inside will also create heat and carbon deposits on the exposed part of the fitting. Yeah you can clean in, but its not good practice.

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