I had a copper (baseboard heat) pipe freeze and burst, and need to replace a run of pipe that's exposed to that kind of cold when it gets below 0F outside. The pipe is below the floor on an exterior wall, and is just a horizontal run between baseboard radiators.

I have a temporary fix in place, but two of my solder joints apparently were bad and have a few little leaks, which I have hose clamps and rubber gaskets over temporarily.

So my question is, would there be a problem replacing this section of pipe with PEX? I like the idea of using PEX since I wouldn't have to solder, and it would theoretically stand up better against the cold (though I am also going to try to address the cold air getting to the pipe).

2 Answers 2


Yes. In fact, I had to do this exact same thing in a house in MN that had baseboard copper freeze and burst in an attic. I ended up replacing the cooper between the boiler and the baseboards with PEX.

I'd suggest using SharkBite connectors to transition between the copper and PEX. They're designed for that and it's super-easy to install.

As Ecnerwal points out, be sure to use PEX with an Oxygen Barrier.

While doing this, be sure to fully insulate the PEX. PEX can withstand freezing, but it's best to avoid freezing in the first place. If you can move it into conditioned space, that'd be best. If not, wrap it in quality pipe insulation (not the cheap stuff but the ones that self-seal).

The biggest challenge might be finding just the small amount of PEX needed as they are often sold in large rolls. You may want to check with a plumbing supply warehouse to see if they'll sell you a remnant piece.

  • Is it okay to use the oxygen barrier PEX for any other projects if I need it? I don't mind buying 100' of it to have around if I can use it for everything... Jan 7, 2014 at 14:11
  • I believe you can. Check with the manufacturer first, of course, but it should work fine. It's likely just overkill for domestic hot/cold water.
    – DA01
    Jan 7, 2014 at 16:02

Unless you have an odd system (bronze or stainless pumps, stainless boiler or heat exchanger) you will need Oxygen Barrier PEX - which , not surprisingly, is the stuff that's typically sold for heating applications. If you use oxygen barrier pex, it should work fine. "Plumbing" pex (non-oxygen barrier) will cause excessive system corrosion in a typical system with cast-iron boiler and pumps.

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