Worried about freezing PEX pipe

[nestsman]

I went to great lengths to ensure the water line coming in to my mobile home is several feet under the ground. That way it won't freeze in the bitter winters that we sometimes get in northern Utah. But then I realized that the manufacturer of the home wasn't quite as concerned. For when the water line comes up into the home, one line goes up into the water heater, the other continues its route under the home, barely covered by some insulation and the underbelly fabric. Inside the water heater closet, the PEX is not covered with any foam or anything, and that closet has a big vent on the door that very cold air could come into.

Am I being too worried about frozen pipes? Maybe PEX holds up to bitter cold nights (15 below zero) better than I realized.

Thoughts?

[Steve-WA]

Pex might freeze, but it's not supposed to split

[1987Commodore]

The line from the ground into the belly must have good insulation and a heat tape on it. The line inside the belly should be run near the heat ducts, which should keep it warm enough there. What you need to do is eliminate any air movement upward from the crawlspace through the belly. The best thing you can do is get some expanding foam insulation and seal every place in your floors where a supply or drain pipe penetrates. The manufacturers usually drill huge holes for the pipes. You may also find huge cutouts under the tub/shower drains. Seal them as best you can.
Any air movement around the line from ground to the home will cause freezing. Wrap your supply line with plastic over the insulation so air movement will be blocked.
I also wrapped my drain line with 6" fiberglass, then over wrapped that with plastic.
If you have exposed pipes in the water heater closet, I'd insulate them also.
Realistically, you will likely still freeze up at some point. Determine where the ice blockage is, and figure a way to insulate that area some more.
If I were you, I would get a torpedo heater to have on hand to thaw it out under there if a problem arises. Just be safe with it, and never leave it unattended. I had to use one a few times until I got all the problem areas sorted out. It would usually only take about 10 minutes to thaw out.

[JD]

I agree with wrapping all exposed and under-insulated water pipes in cold weather areas. I would not do anything with the hole in the water heater compartment (usually a square hole with hardware wire screen . It is there to supply air to the water heater.

[countrydan]

Fwiw...

My wife and I purchased a foreclosed doublewide in southwest michigan. It has pex and was sitting vacant for a year or so I believe. Well the p traps in all the sinks and the porcelain toilet bases busted out from freezing water.

The pex did not have one split though. Maybe it was closer to the insulation in the crawl space, who knows, but it lasted through a decent winter that caused damage inside the house...

I am a firm believer in pex now

[ponch37300]

Pex will hold up to cold very well. I'm not positive the exact numbers but I thought I read it can expand to 3 times it's original size before it breaks. When I moved into our current place our master bath which is on the end of our single wide would freeze in the winter. But they never burst. Before I moved in the toilet drain had froze and backed up and the insulation was garbage and there was some holes in the belly material. I put new insulation in and fixed the belly material and no more problems with freezing pipes. The temps drop into the minuses, think our low was around -30 or so last year and the only problem we had was with the water meter freezing and bursting, one of 4 in the park that night.

As long as the belly material is sealed good and the insulation hasn't been compromised by getting wet the heat from the duct work seams to keep the pex from freezing.