PEX vs. PVC - curious

Back when I was getting started on finding my RV, I did the factory tour with Earl.  When he mentioned PEX, I asked more questions - my grandfatherr had taught me plumbing with various types of pipes and this was new to me.  He took me to the plumbing nook and showed me the parts they used and talked about the advantages.  Fast forward to my recent plumbing issues.  When they were showing me the lines that go thru below the wardrobe,  it isn't PEX.  It is PVC.  So I am curious if you guys know which your rigs have and how PEX disappeared from the time of the tour to the build.  Changes the type of problems/fixes to anticipate behind a wall it seems.  Not saying one is better than the other, just another surprise in my RV life.

Hi catsaplenty--

I can only comment based on personal observation.  When I was getting ready to order my 2552 in late 2018 I visited the factory and spent some time alone wandering around the build area.  Being a "technically oriented" guy, I looked closely at a number of units in various stages of the build process and took a lot of photos.  Double checking those photos today, I see (and saw in person then) only PEX being used for the plumbing supply lines--that includes hot and cold water supply to the kitchen sink, water heater, the bathroom shower and vanity, and outside shower.  All the PEX was white--for both hot and cold supply--instead of the red and blue commonly used in residential applications; most of the supply looks to be 1/2 inch, with brass fittings and brass crimp rings.
The drain and waste lines are a larger (1 1/2 inch) black plastic pipe--they look to be either Schedule 40 ABS, or ABS/PVC composite drain piping--which are both another thermoplastic compound similar to PVC; they are glued together with the same assembly process used for PVC piping.

Nowhere did I see conventional white PVC pipe used in the build of any of the units.  If the lines you saw below your wardrobe were the small supply lines, it is possible that a segment of the white PEX supply lines looked like PVC--one now normally expects to see either red (for hot) or blue (for cold) lines when they are PEX.  However in late 2018 Phoenix was using all white for some reason, which resembles a small piece of PVC pipe.

All the best,        Mike

Here are a couple of the photos I took showing the white PEX supply lines and black drain lines.

 IMG_0930 by Michael Henry, on Flickr

IMG_0927 by Michael Henry, on Flickr

What mikeh said is what I have understood is the practice going back to at least the 2007 model year, but likely for some years prior to 2007, maybe from the beginning in the late 90's.

Interesting but these are PVC in mine.  They have PVC connections to turn the corner, not brass.  I guess this will be a curiosity.  I haven't had reason to play in the rest of the plumbing to know what it might be.  Thanks for chasing down old pictures. 

Wow--that is very interesting catsaplenty.

That is worth a question to Phoenix if the time is ever right.  Based on everything I've seen over time, they have been firmly locked in to PEX water supply lines for a very long while.  It makes sense, because it is a quicker install than PVC.  Earl told you they used PEX prior to your build, and the 2018/19 builds are PEX, so if they deviated to PVC briefly in 2017 for some reason, it would be interesting to know why.  Maybe JATRAX or GANDALF42 will see the thread and comment--both of their 2552's are 2017 models I believe.

Mike

Mike, I found your explanation to be spot on.  Also, just for my two cents worth - or maybe only one cent worth - the boating industry has been using PEX since about 1999.  In addition to the simplicity of crimping versus solvent welding, PEX is far more flexible for bending around a curve eliminating the need for rigid, 90 or 45 degree fittings.  PEX also is far more tolerant to vibration than PVC.

I agree Mike, but unlikely I will get any more from the factory on this.  I voiced my surprise while I was there.  And I agree it would have been more forgiving in many ways.  But as I keep saying - it is always a surprise.  I had one of the early 2017s when they had made sooo many changes at once, understandably, not all went as they would have liked.  There was much mystery in my whole build - some may remember that angst when they didn't build it the way it was ordered.  Hard to say what all was going on back then. 

Appreciate all the response and intrest in my question.

Lots of interesting comments on the pipe issue.  Couple things to consider:  Schedule 40 PVC (Poly Vinyl Chloride) cannot be crimped.  It has to be solvent welded.  Schedule 40, regardless of size is the only PVC rated for pressure.  Schedule 20 aka "thin wall" is not rated or used for pressure.  Schedule 80 is used for extreme pressure.  PEX has been the go-to pipe in boats, RVs, mobile homes and homes in general for quite a few years now.  Typically, you now see PEX in blue for cold and red for hot in these applications.  Any pipe related to drains in the boat/mobile home/RV industry is typically black ABS (Acrylic Butyl Styrene)  ABS as well as DWV (drain, waste, vent) used in homes has different nominal dimensions so it can't be used under pressure.

Schedule 40, regardless of size is the only PVC rated for pressure.  Schedule 20 aka "thin wall" is not rated or used for pressure.  Schedule 80 is used for extreme pressure.

Hi Jim!
Couldn't resist a comment.  Schedule 20/pressure----"Rated"--YES; "Used"--NOT NECESSARILY!
Would you believe that I bought a newly constructed house as an investment some years ago--and after a couple years got a call about a water leak in the 200 foot run from the meter up to the house.  Dug it out and was amazed to find that whoever subcontracted the plumbing ran Schedule 20 PVC in the same trench for both the water and natural gas supply lines.  The gas was holding, of course, with only a few ounces of pressure--but it didn't take long for that Schedule 20 water supply to fail.  Rented a trencher and ran the proper stuff for both lines--but I guess it is possible to "use" Schedule 20 for pressure--just don't expect it to hold up!

All the best,      Mike

Wow, Mike.  So unusual.  While Sch 20 may hold pressure, it will not meet any plumbing codes for such use.  My experience is that we always used Sch 20 for underground irrigation.  A bit like PEX, it will bend around a slight curve.