Water pump pex choices

Robermcm

In inspecting the Alde under bed  area of my new to me tab 400, I found a collapsed pex hose. It runs from the nautilus manifold mess to the filter side of the water pump. 

This foot long piece of pex is the braided, reinforced version, which is softer than the standard, hard sided pex that’s in most other places. See picture. 

It was run poorly, as a remounting of the water pump or a few elbows in the line would have made it free of other’ hard sided’ pex. But they didn’t.  I’m going to fix this as I suspect water flow has to be severely constrained and a cracked pipe would also be no good! 

If this is the inlet side of the pump, might the collapse be, in part, because they used a soft sided pex here in a vacuum situation??  I lightly warmed this pex and it got very soft. So I suspect summertime operation to be soft piping all the time. 

I also wondered if there is a condition where the nautilus valve is ‘closed to pump’ and someone can collapse the pipe by running it dry. And in my poorly routed situation, it would possibly not return to round. 

Curious as to others experience with this.  

Thanks

elbolillo

The blue and white braided tubing is PVC. Usually used where some flex is needed.

bergger

I'm not a plumber but have recently been looking into proper vs improper RV plumbing.  From what I've learned pinch clamps should not be used on pvc tubing.  The pvc tubing will expand and contract significantly more than pex tubing and can cause leaks if the wrong fittings are used.  The fact that NuCamp used a pinch clamp on it means the fitting at the pump is most likely the wrong type.  It is probably a pex fitting and not a pvc fitting.  If it is a proper pvc fitting the pinch clamp should not fit over the pvc tubing as the barbed fitting for pvc is larger than a pex fitting.  If replacing it I would source the proper fitting and secure it with a worm gear clamp.   

In your photo the other hot water pvc tube in the background, with the red lines, is most likely installed incorrectly as well.  It has a pinch clamp and appears to be installed on a pex T fitting and not a pvc fitting.  

Apparently this incorrect plumbing is rampant in the RV industry as it is just easier and cheaper to do rather than use the proper adapters to attach pex and pvc together.   And there are no codes that control RV plumbing, unlike residential and commercial plumbing.  So they just do it.  I plan on inspecting all the pvc lines on our 400 this year and will either replace anything installed incorrectly or just keep a close eye on them and replace them if they start to drip.  

Robermcm

bergger said:

I'm not a plumber but have recently been looking into proper vs improper RV plumbing.  From what I've learned pinch clamps should not be used on pvc tubing.  The pvc tubing will expand and contract significantly more than pex tubing and can cause leaks if the wrong fittings are used.  The fact that NuCamp used a pinch clamp on it means the fitting at the pump is most likely the wrong type.  It is probably a pex fitting and not a pvc fitting.  If it is a proper pvc fitting the pinch clamp should not fit over the pvc tubing as the barbed fitting for pvc is larger than a pex fitting.  If replacing it I would source the proper fitting and secure it with a worm gear clamp.   

In your photo the other hot water pvc tube in the background, with the red lines, is most likely installed incorrectly as well.  It has a pinch clamp and appears to be installed on a pex T fitting and not a pvc fitting.  

Apparently this incorrect plumbing is rampant in the RV industry as it is just easier and cheaper to do rather than use the proper adapters to attach pex and pvc together.   And there are no codes that control RV plumbing, unlike residential and commercial plumbing.  So they just do it.  I plan on inspecting all the pvc lines on our 400 this year and will either replace anything installed incorrectly or just keep a close eye on them and replace them if they start to drip.  

Thanks for the education. I’m new to pex and didn’t make the jump to a soft tube not possibly being pex of any type. 

There’s pvc all over my 2023 400. To the toilet, that white/red is to the mixing valve, a sister white/blue one to the other side of that valve. An all white pvc tube leaving the water pump. The most silly use was to that pump inlet where it could collapse easily and forever. It’s as soft as a baby’s bottom when warm. More things to fix!

bergger

There is nothing wrong with flexible pvc tubing.  It just needs to be connected properly if joined to pex and other fixtures.  I've casually noticed in our 400 that there are proper pvc connections and some that appear improper.  As I'm pretty thorough with inspecting our trailer, and drain it after every trip I'll probably just keep an eye on areas that use pinch clamps and replace them if they ever drip.  If the run is short and the pvc is connected using pex fittings you can always replace the pvc with pex.  However this often requires more elbows and connections since pex is not very flexible over short runs.  Hence the use of pvc.  

elbolillo

I really don't think that the pump running had anything to do with the kink that you see in that tubing. And I haven't noticed that tubing getting so warm as to be extremely pliable.

ScottG

bergger said:

...

If the run is short and the pvc is connected using pex fittings you can always replace the pvc with pex.  However this often requires more elbows and connections since pex is not very flexible over short runs.  Hence the use of pvc.  

FWIW, there are "bend supports" for PEX that will coax it into a small-radius 90-degree curve. I used them liberally in my house. At the time (25 years ago) PEX was relatively new and one of the touted benefits was the ability to make "home runs" to fixtures thus eliminating the need for multiple connectors and fittings (and possible leaks). It's a little funny that PEX is now being installed in much the same manner as rigid copper pipe.

Robermcm

ScottG said:

bergger said:

...

If the run is short and the pvc is connected using pex fittings you can always replace the pvc with pex.  However this often requires more elbows and connections since pex is not very flexible over short runs.  Hence the use of pvc.  

FWIW, there are "bend supports" for PEX that will coax it into a small-radius 90-degree curve. I used them liberally in my house. At the time (25 years ago) PEX was relatively new and one of the touted benefits was the ability to make "home runs" to fixtures thus eliminating the need for multiple connectors and fittings (and possible leaks). It's a little funny that PEX is now being installed in much the same manner as rigid copper pipe.

I bought one of those curve supports. Robust hunk of plastic!  Trailer plumbing is like house plumbing in miniature.  No room for graceful curves. And the back of that nautilus panel is enough to give me the whim whams. Many semi loose screw on parts. 

On a side note, I wrote to nu_camp sharing  my kinked hose issue. They were super responsive even though I’m not covered by warranty. And they’re sending replacement parts. Will be curious as to whether they will just send two oetiker clamps and another piece of pvc or a more elegant solution.