Connection between Copper and Pex pipe broke in extreme cold

Question

During extreme cold month of Feb in East coast, my baseboard radiator pipe broke, basically the connection between the copper and pex pipe broke and water leaked all over. I called a contractor and he fixed it and put it back together.

But i am afraid it will happen again this winter. How do i make sure it doesnt happen again? Is it because PEX pipe expands/contracts ? Not even sure why the connection would break in the first place.

Any responses/sugessions will be greatly appreciated. Thanks all in advance.

Answer 1

Your "before" picture is too blurry to be useful, so try to remember: Did the end of the copper look like picture 1 below or picture 2?

Picture 1 follows. This is a pex crimp coupling.

Picture 2 follows. This is a copper reducer not suitable for pex.

If it looked like picture 1, then as crip659 said, it should last forever.

If it looked like picture 2, it's a hack job and that's the reason it came apart in the winter. A length of pex will get a little shorter in the cold and longer when hot water runs through it. If your baseboard radiator does not have a proper pex fitting on it, the pex tubing has no ridges to grip. If there is no slack in the pex tubing, it can pull right off the copper fitting due to shortening in extreme cold.

So if it looked like picture 2, you have another disaster waiting to happen. The proper fitting costs less than two bucks. Labor is extra.

(images from SupplyHouse.com)