PEX Fittings: Freeze Safe?

Are the contents of the tube freeze/thaw stable?

Only trouble I can recall with PEX tube fittings is possible dezincification when using yellow brass fittings.

Don,

How cold are you talking about? I would expect the crimp bands to be more of a concern than the fittings. Of course the whole thing depends on the amount of dissolved gas in your water and the rate of freezing.

Are you living in an area that is subject to freezing or did I miss the announcement of the upcoming ice age?

In order to answer the question, determine which metal(s) is/are present, the temperature(s) it/they is/are likely to experience, and compare it to the fitting manufacturer's published data. If no published data is available, review the temperature range with the fitting manufacturer's technical helpline by telephone.

Thanks for the replies.

The contents of the PEX is treated well water. I live in south Louisiana but we do experience subfreezing temperatures. In 2011 the temps were below 20 degrees F for 3 days in a row. One of my neighbors had an exposed PVC water line freeze and burst.

Builders here don't build for the cold. Most water pipes are run through unheated attics, and ouside water faucets are prone to freezing unless the water is run throughout the freeze period. The PEX lines in question were running to the outside compressor unit of a heat pump. The water picked up the heat from the unit and fed it to the domestic water heater. The new HVAC unit that was installed is not compatible with the water heater "pre-heater". So, I have two exposed PEX lines.

The fittings and crimp materials appear to be brass but I'm not sure. I do not know who manufactured the materials. The house was built in 2004.

Will it freeze with water inside? If so, the PEX is OK, it will stretch and recover, but metal parts could be damaged. As I'm sure you know, an all-metal system (pipe and fittings) will be damaged by freezing.

I have pex tubing for both my radiant floor heat and all domestic water lines. The floor heating uses an electric heater in a closed glycol system so that is freeze proof. The domestic lines have frozen on us a few times during power outages here in the Buffalo NY area(-10 and colder). We only had damage to one faucet. The PEX lines and fittings survived with no issues.

Thanks. Here's a reply from a manufacturer:

Hi Donald,

PEX is not freeze-proof. It is freeze resistant, and the most freeze resistant PEX there is, is PEX-A because of its flexibility.

The plastic fittings are probably more freeze-resistant than brass fittings, but I would not say that they would be safe in sub-freezing temperatures.

Honestly, it is not advisable to use PEX in applications in which you know the water will freeze.

If the PEX and PEX fittings are exposed to sub freezing temperatures, and if they cannot handle the temperatures, then I would assume that the fittings would be the first to break.

GA.....thanks.

If the water freezes in the PEX on both sides adjacent to the metal fitting, then freezes in the metal fitting, then the metal fitting would probably crack. If the water freezes in the metal fitting first, the ice forming would likely expand out into the PEX with no damage to the fitting. As NotUrOrdinaryJoe commented PEX has to shielded from sunlight (ultraviolet light) as well as fluorescent lighting as I regrettably found out.

Consider insulating your lines, and adding a heat trace line inside the insulation. In Canada, they sell 120V plug in electric resistance heat trace lines that operate on a contact thermostat. They turn on when the pipe gets close to 0C (32F). This is likely lower cost than running extra lines and circulating with a pump.

Some PEX is not rated for high heat, so this is something to consider.