PEX tubing questions

[Stu Rasmussen]

Reading the recent thread about changing 40 year old water lines for
PEX engendered two questions:

1: What size PEX would be suitable to get the same flow as the
existing piping?

2: Is PEX burst-resistant enough to re-route the replacement piping
under the coach (easy) instead of snaking it through the existing
routing (convoluted)? I'm thinking here about resistance to bursting
due to freezing.

Inquiring minds and all that . . . .

Stu

 

[bdub]

One caution, the tubing is burst proof, BUT and fittings are NOT.

 

[mark sawyer]

> One caution, the tubing is burst proof, BUT and fittings are NOT.
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Though often when a PEX system freezes, the freezing water in the fittings will expand out into the tubing instead of bursting the fittings... That
is not to say they can never burst, but we had a good hard freeze of our home during the Texas blackout... And no pipe damage at all.. (Thank
goodness) And our house even has 2 hot water heaters in the attic and all the associated piping exposed to un-insulated space...

Love Pex...

FWIW, I even plumbed the air in my shop using PEX and sharkbite fittings about 12 years ago. Not a single problem or leak in that time. And pex
splits when it bursts... No shrapnel like PVC would...

If you're going to work with it much, it's handy to pick up a tubing cutter like this:

https://www.amazon.com/RIDGID-23488-PC-1250-Single-Plastic/dp/B0019MLSLS/ref=asc_df_B0019MLSLS/?tag=hyprod-20&linkCode=df0&hvadid=241955516116&hvpos=&hvnetw=g&hvrand=11029197398631820957&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9027244&hvtargid=pla-452665437979&psc=1

Works great on vacuum and radiator hose as well. Nice clean, square cuts...

--
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX

 

[s-m-h]

I redid all my water lines with half inch pex. Color coded blue and red. I didn't go under the coach but would have no problem doing it. Just put a
drain cock at a low point and you'll be fine.

Shawn
--
Shawn Harris
North Vancouver,
Canada
1977 Palm Beach 403

 

[blur911sc]

We were staying at our cottage one winter and had a heating system failure when we were away overnight and froze it hard, it was -15C inside when we
got back.

The only leaks we had once everything thawed out was the 2 feet of copper in the shower running to the showerhead and the kitchen sink spout split as
well. All the distribution lines are PEX with mostly crimped fittings and a few compression fittings. It's great stuff, the cold water line under
the sink would freeze every time it got really cold and the wind was the right way, never a leak.
--
Burl Vibert
Kingston, Ontario
1976 GMC 26 foot, Sheridan reno, don't know original model but we call her Roxie

 

[Richard RV]

Stu,

3/8" and 1/2" are the two most common PEX line sizes, with 1/2" being the most common in residential construction. It may not be desirable to have
high flow in an RV, particularly one with smaller holding tanks like a GMC. If you're frequently at campgrounds and hooked up to the sewer than flow
rate and holding tank filling efficiency doesn't matter. Generally speaking, a 3/8" line will deliver good flow.

The 1/2" line will have a flow rate ~2.5x that of a 3/8" line. If you're planning on having an "instant water heater" it will require a higher flow
rate to trigger the heat, which might be at the upper end (or beyond) what a 3/8" line can deliver.

I don't know that counting solely on the freeze resiliency of PEX is wise. Running the water lines under the coach means that they'll freeze sooner
than if they're inside the coach. If the line freezes water won't flow. You could insulate and/or heat trace them to compensate if you're frequently
camping in colder weather.

Of course you will still need to winterize the coach, and your drain valves will be at the lowest point and underneath the coach, so you'll have to
get under the coach to winterize instead of doing it from inside.

Richard
--
'77 Birchaven TZE...777;
'76 Palm Beach with 18,477 verified miles;
‘76 Edgemonte

 

[douglas smith]

Stu,
I redid my '73 with half-inch pex and did not find it too difficult to get access and pull tubes without taking much apart. Yes, the over the ceiling
runs were the worst but not bad. If you use whatever's existing as a puller it's not a difficult job. Can't speak for the differences between '73 and
'77 for this task.
Doug
--
Douglas & Virginia Smith,
dsmithy18 at gmail,
Lincoln Nebraska,
’73 “Sequoia” since ‘95: "Wanabizo";
Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy wheels/Sundry other

 

[sgltrac]

I used 1/2” pex in The War Pig and it was fairly easy to pull into place.
The struggle I remember was bending long runs around corners. Yeah I
could’ve used a brass elbow and two more compression fittings but I wanted
to minimize the number of connections. The support bracket for pex 90s has
a pretty large radius.

Sully
Bellevue wa.

> Stu,
> I redid my '73 with half-inch pex and did not find it too difficult to get
> access and pull tubes without taking much apart. Yes, the over the ceiling
> runs were the worst but not bad. If you use whatever's existing as a
> puller it's not a difficult job. Can't speak for the differences between
> '73 and
> '77 for this task.
> Doug
> --
> Douglas & Virginia Smith,
> dsmithy18 at gmail,
> Lincoln Nebraska,
> ’73 “Sequoia” since ‘95: "Wanabizo";
> Quadrabag/6 wheel disks/3:70 final/Paterson QuadraJet/Thorley’s/Alloy
> wheels/Sundry other
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