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Community and Q&A

Sweating pipes in the wall

DIYJester | Posted in General Questions on

Hi everyone, I’m trying to rig up some temporary water to a shower because my waterlines are frozen again.

The issue I’m having is the fixture has 1/2″ PEX to copper crimp on/sweat connections that I have to get off. I could easily use Sharkbite type fittings to reinstall the new line with the only concern being the depth of the 1/2 copper required to “bite” correctly. If this was not a concern I would hit it with my hacksaw.

The wall is basically 2 2×4’s thick and has a decent amount of blown in cellulose packed in where I’d like to work. My obvious concern is starting a fire while trying to disconnect or connect the fittings.

Are there any readily available products or techniques I could use to prevent a fire? The current fittings look to be some type of copper sweat on fitting with a barb and a steel clamp over the barb fitting. I could probably cut the steel clamp, but I don’t know if I need a special clamping tool for re-install. Thanks in advanced, this site is great!


Thanks ,as always, to Jeff Weiss (formerly, not sure anymore) of Green Valley AZ for not disclosing this tidbit in the sale disclosure.

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  1. GBA Editor
    Martin Holladay | | #1

    My advice is to call a plumber. Plenty of people have burned down their house doing what you are planning to do.

    That said, here are the tricks that plumbers use:

    1. You need to install a heat shield between the copper tubing and combustible materials behind the tubing. You can get a heat shield at a plumbing supply house, or you can use a scrap of heavy galvanized steel flashing, a piece of an old stove pipe, or a discarded tomato soup can that has been cut open with shears.

    2. You need to wrap the copper tubing on both sides of the new fitting with damp rags.

    3. Even if you follow the advice I just gave in (1) and (2) above, you can still burn down your house.

  2. DIYJester | | #2

    Thank you for the advice. I think I'll be cutting the bands over the barbs and cutting the PEX. I'll then press new bands on. There is too much to work around to truly be safe. I have less than a 1/2" between the joint I need to sweat and the shower surround, a 2 x 6 and plenty of cellulose.

    I work for a company that is very involved in hot work and hot work permits and realize that this is one of those cases where a fire is very likely.

    I wouldn't trust a plumber around here since this is how my house got into this mess in the first place. A licensed plumber ran the lines in the attic with no insulation or heat trace. Two separate licensed HVAC contractors designed and installed a heated floor with no insulation. There may be a few good ones around but I don't have the time to experiment. The only up side would be they have insurance too.

  3. charlie_sullivan | | #3

    There's an inexpensive PEX band crimping tool intended for occasional use by homeowners that is basically just the die with no handles. You sqeeeze it shut with vice-grips. It's way too slow for a professional plumber but just fine for occasional repairs. It's worth having at least that if you live in a house with PEX plumbing, especially if you don't have a plumber you trust.

    I once tried to rig up heat protection for some soldering using aluminum foil tape. The adhesive on the tape caught fire. Fortunately, the building did not.

  4. DIYJester | | #4

    Thanks Charlie,
    I am just going to use a standard coupling and my wife just picked up the crimp tool that you suggested. I will have plenty more to do in the future, but I'm not all that worried about the extra time it will take to spend the extra $40. I also decided to just cut the PEX further from the shower valve to make it easier to work with. Hopefully we won't need to run any other temporary lines.

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