Unsweat joint, preserving adjacent joints?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Jack Foster, Jul 24, 2017.

  1. Jack Foster

    Jack Foster New Member

    Joined:
    Jul 23, 2017
    Location:
    Nevada
    Good morning. First off I’d like to say that this forum is a wealth of knowledge. I have had quite a few plumbing projects this season, and can usually find great advice from the folks here.

    I’m currently gathering all supplies and knowledge for replacing my 13 year old water heater, and have one specific question regarding unsweating a copper joint.

    I would like to keep my existing cold water shutoff valve and copper plumbing to the expansion tank if possible, because the original plumber left no spare pipe to cut and sweat on new without opening my wall, which I am not comfortable with. The valve and copper to the expansion tank are in very good condition, so I’d rather leave all that alone if possible. This leads me to my question of unsweating near joints to be left alone: I would like to simply unsweat the existing copper flex cold water supply line by applying heat just to that fitting or a little behind it, prepping the existing pipe stub, and then sweating on a new ¾” MIP nipple for a new copper supply. I just don’t know if it’s possible to do that without compromising the adjacent tee fitting that is only approximately ¾” away. I would of course wrap the tee fitting with a cold wet rag to reduce the heat it would be exposed too, but I don’t know if that would be enough to protect it from the sweating taking place less than an inch away. Is my plan valid at all, or is the adjacent joint bound for failure due to the fitting replacement taking place so close to it?

    Thank you all for your help,
     
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    I am not a plumber.

    I would mechanically secure the tee so that if its solder were to melt, it could not pull apart. What I would use to do that would depend on circumstances. That includes which leg of the tee is where.

    I might bind things with thin steel wire (bailing wire) if I had that and it would do the job.

    I don't think I would worry about just melting the solder causing a problem, but rather melting accompanied by movement in the joint.
     
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  4. Terry

    Terry Administrator Staff Member

    Joined:
    Aug 17, 2004
    Occupation:
    Plumber
    Location:
    Bothell, Washington
    The wet rag helps there. I've done it quite a few times, same situation.
     
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  5. dj2

    dj2 In the Trades

    Joined:
    Aug 13, 2013
    Location:
    California
    Considering all the information you gave, I would suggest that you use all new fittings.
    Or, get an experienced plumber to do just that, prepare everything for you to replace the WH.

    The reason: Realistically, I don't believe that you can handle this job, unless you want the practice and willing to re-do it more than once.
    Unsweating old fittings always has unforeseen difficulties.
     
  6. Jack Foster

    Jack Foster New Member

    Joined:
    Jul 23, 2017
    Location:
    Nevada
    You make an excellent point. I know that when I pull and twist the old supply line, the short stub of pipe could move in the end of the tee which I want to preserve. I guess I just need to hope the wet rag will prevent the solder in the tee from becoming molten long enough to pull the old supply line. Thank you for your advice.
     
  7. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
    Feb 6, 2011
    Occupation:
    Semi-Retired
    Location:
    NW Ontario, Canada
    They do certainly present challenges as there is often solder left behind that makes insertion of the pipe or fitting difficult. If you have the room to get at it, sometimes you can shave off a bit of the solder with a sharp blade. Other times you may need to apply heat prior to full insertion but that can get tricky. I've also heated the fitting and then quickly ran the wire brush through it.
     
  8. Jack Foster

    Jack Foster New Member

    Joined:
    Jul 23, 2017
    Location:
    Nevada
    I do have all the new copper sweat fittings, pipe and valve on hand to rebuild the assembly in the event my unsweating attempt fails. I am comfortable sweating copper, and have had excellent results in the past, but have never done it close to wall studs or sweat valves. So.... the valve I bought is a Shark Bite ball valve (perhaps an unfavorable option to the folks on this forum). Again, hoping not to have to deploy this option, but the SB valve would prevent me having to open the wall (for flame hazard), and I would not be sweating a valve material that I've heard can be difficult to sweat. I also understand that if I use the SB valve I will need to brace the expansion tank, due to the fact the the SB valve will allow rotation of the assembly.
     
  9. Jack Foster

    Jack Foster New Member

    Joined:
    Jul 23, 2017
    Location:
    Nevada
    I have been practicing my unsweating techniques with old pipe and fittings. I have gotten great results by heating the fitting, pulling it free, and then wiping it quickly with a dry rag. It leaves the color of the solder on the pipe, but I cannot feel any solder build up. I then prepare the new fitting and pipe stub as usual, and everything goes together as normal. Just unsure if the heat would jeopardize the adjacent fitting in any way.

    Thank you for your input.
     
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Joined:
    Feb 6, 2011
    Occupation:
    Semi-Retired
    Location:
    NW Ontario, Canada
    Ja, the male end is the easy part. Inside the fitting is a tad harder. I've done the equivalent of the rag wiping with the round wire brush meant to do inside fittings. you could also try a small dremel flap wheel sander on a low speed.

    Adjacent fittings are a significant enough of a heat sink that there is little chance you will melt the solder on them. A scrap of tin to deflect the flame should be enough. They do make a heat resistant cloth as well for sweating in tight places.
     
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