Help plugging water supply line under slab?

This week serves as another reminder: pex (or any piping for water) through the ceiling needs to be protected from freezing temperatures (I still don’t regret doing mine, but I do need to figure out how to better protect it from freezing, though a drip has worked just fine so far).
I think putting it in the water heater closet makes all the sense in the world. Putting it in the attic makes zero sense to me for a variety of reasons (see above for one)…

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There are no definites in freeze protection short of draining the line or it being below the frost line. You could heat trace. Could insulate or run the water. If you did all 3 or a combination of those your odds would be better. I’ve seen moving water freeze in TX, I’ve seen heat trace fail or not be enough. I’ve seen insulation not work either.

Just keep it in mind. What is getting rid of your single point of failure worth to you.

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PEX is freeze tolerant. It won’t split like copper.

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While true, repeated freezing will cause earlier failure than not freezing. And, while it’s true that a split supply line, once thawed out, is a bigger pain in the ass, frozen pipes don’t allow flow, so you’re stuck without water at those faucets until they’re thawed.
And since we’re talking about it, drip the hot, if not both. Pipes burst from the excess build up of pressure when ice forms, not from the ice itself. Having an escape for the liquid water will help prevent bursting, even if the water inside the pipe freezes. Toilet valves tend to allow bypass of cold water when the pressure gets high enough, while hot water tends to have no “loose” valves, and end up being the ones to burst. I’ll post source study if I can find it again…
EDIT: found. https://www.nytimes.com/2014/01/09/garden/if-winter-takes-aim-at-the-pipes.html

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Is freezing that big of a problem here in Texas? As a kid growing up and in the 2 houses I’ve owned (1956 and 1978 construction respectively), I’ve had one pipe freeze in a bathroom that was out by itself on an island with an exterior wall. That was a simple instance of throwing a heater in the room.

My guess is that with PEX, it is resistant enough to freezing that it’s not a problem in our climate. It also doesn’t transfer heat like metal lines.

I’m planning on insulating any lines in the attic as well as the exterior entry point (of course). The other benefit is that your hot water stays hot in the line longer, but none of my runs are very long anyway.
Here’s the rough plan:

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It is if you run your water through the attic instead of the ground.
You need to heat/insulate/otherwise monitor/protect it from freezing.
For my run, the “repair” tee is in the garage (no climate controls) on an exterior wall (minimal insulation, being part of an uncontrolled area) and then about 10’ through the attic above said space. Poor insulation (I suspect) is the culprit, and it HAS frozen, though without bursting the PEX (thankfully). Now that I know, I can plan, and have had no problems since. But that first freezing evening was a royal PITA. I am fully convinced that just letting it happen every time would hasten the destruction of my PEX, which is not all that resilient to repetitive flex. I also think in Texas this can actually be WORSE than in a northern climate, because we only freeze for a day or 2 here, usually, so you’d get several heat/thaw cycles annually, unlike the great white north where it usually goes below freezing for the winter, and then thaws come spring.

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Ok, so I’ve run the new supply line (3/4” PEX) to the exterior wall like the plumber wanted to do. Next per his plan, it will go up the outside of the wall and enter the attic… the question is, how do you mount/insulate it? I have exterior rated pipe insulation, and I was going to put some sort of housing around it (hardiboard, etc). Any suggestions?

Look up line set covers. The residential HVAC folks use them for retrofits when they have to run a new line set.

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