Take some plumbing advice cautiously

[Rabbit]

There’s a reason plumbers have to be certified/licensed. Doing a plumbing job wrong can result in property damage, health related dangers, not to mention inconvenience or wasted money. I have over fourth years in the drinking water industry with a leading company that makes fittings for water and gas lines, including the sorts used in RVs. I cringe when I read posts that give advice for connecting PEX pipe, replacing a vacuum breaker, not using a water pressure regulator, or modifying the propane piping. All of these involve observing product specifications, government regulations or good practices guidelines. Two of my pet peeves involve PEX, and black tank flush systems. PEX pipe is the extruded plastic pipe used in buildings and RVs. This pipe (rigid or flexible) has a hard smooth Outside and inside surface. Braided tubing is not interchangeable in all applications. Braided tubing is soft and has an outside surface that is not uniform (smooth). Fittings that rely on an o-ring to seal, such as SharkBite brand and similar, are not certified for use on braided tubing. Barbed fittings with pipe clamps (worm gear, even PEX clamps) are about the only reliable connection. O-ring fitting MIGHT be made to seal, but the seal will not be reliable for the long term, especially with vibration.

Black flush systems involve dangerous waste. The vacuum breaker in the water line is REQUIRED and must be installed high up above all drains in the RV. Don’t ever defeat it by replacing with a piece of tubing, or install it lower than any drain or toilet bowl.

Pressure regulators should always be used, especially in hilly or mountainous areas.

If you must have the details, do your research. Or better yet, call a licensed plumber or trained tech person.

[Always Learning]

With your experience what do you think about the way Grand Design mixes the soft hose and PEX in the construction of their trailers. If you have not had any problems with the plumbing in your trailer then that is great. What ever you do don’t touch the connections behind the Nautilus panel. I replaced my water pump the other day and in the process caused one of the connections behind the Nautilus to leak. By the time I got that connection fixed a three way tee was leaking. By the time I got the leaks fixed I had spent all afternoon. The braided soft hose GD uses is slightly larger OD than PEX and needs to be heated to get PEX clamps on and the ID is much larger than the PEX connectors that GD uses which causes the leaks.

What are your recommendations for fixing the soft hose leaks that result from GD using PEX connectors that are much smaller then the soft hose ID?

[TravelHabit]

... PEX pipe is the extruded plastic pipe used in buildings and RVs.

Mine is all braided tubing as far as I can tell. I'm thinking of replacing it so everything is PEX. GD says braided tubing is the "industry standard" but that does not make it a good design. I seriously doubt it would be acceptable to any of the major home building code organizations.

[Rabbit]

With your experience what do you think about the way Grand Design mixes the soft hose and PEX in the construction of their trailers. If you have not had any problems with the plumbing in your trailer then that is great. What ever you do don’t touch the connections behind the Nautilus panel. I replaced my water pump the other day and in the process caused one of the connections behind the Nautilus to leak. By the time I got that connection fixed a three way tee was leaking. By the time I got the leaks fixed I had spent all afternoon. The braided soft hose GD uses is slightly larger OD than PEX and needs to be heated to get PEX clamps on and the ID is much larger than the PEX connectors that GD uses which causes the leaks.

What are your recommendations for fixing the soft hose leaks that result from GD using PEX connectors that are much smaller then the soft hose ID?

See response below.

[Always Learning]

See response below.

Sorry I don’t see any additional information.

[Rabbit]

Mine is all braided tubing as far as I can tell. I'm thinking of replacing it so everything is PEX. GD says braided tubing is the "industry standard" but that does not make it a good design. I seriously doubt it would be acceptable to any of the major home building code organizations.

Unfortunately it is acceptable per CSA for the RV industry, which the US accepts, but braided hose/tubing is not per standard in US building codes as supply line. Personally and from experience in the waterworks industry, I don’t like it. PEX clamps were make to use on extruded PEX pipe, which I believe is ID controlled. Perhaps the clamps used on RVs is special somehow. I don’t know. The RV industry uses it for obvious reasons and if the clamp is installed correctly and the stars are aligned, that use is I guess okay. But! If not clamped sufficiently or the fitting or tubing is not on tolerance, maybe not. The company I worked for made slip on self clamping o-ring sealed plumbing fittings that were not guaranteed to work on anything other than pipe and tubing with a smooth OD within certain tolerances. That’s not braided hose. And I agree, if it doesnt leak don’t mess with it.

[Always Learning]

And I agree, if it doesnt leak don’t mess with it.

Unfortunately as the system ages they do leak. When I say touch the connection all it takes is a little pressure or a slight pull on the line and a leak is created. I would think the RV industry is large enough to have custom hoses and/or connectors made that work for both PEX and soft hose if they want to put both in the trailer.

The soft hose connection leaks are why there are threads on this forum about owners replacing all soft hose with PEX. Why is it the customer/end users responsibility to repair badly designed and implemented systems in these trailers. This forum is great because other owners posted about the leaks and I added PEX tools, connectors, clamps and spare PEX pipe to my repair kit. We are full time and always in the middle of no-where so I have to be prepared to fix any problem I can. I have had previous trailers with all PEX lines and never had any leaks. (End of rant)

[Rabbit]

Unfortunately as the system ages they do leak. When I say touch the connection all it takes is a little pressure or a slight pull on the line and a leak is created. I would think the RV industry is large enough to have custom hoses and/or connectors made that work for both PEX and soft hose if they want to put both in the trailer.

The soft hose connection leaks are why there are threads on this forum about owners replacing all soft hose with PEX. Why is it the customer/end users responsibility to repair badly designed and implemented systems in these trailers. This forum is great because other owners posted about the leaks and I added PEX tools, connectors, clamps and spare PEX pipe to my repair kit. We are full time and always in the middle of no-where so I have to be prepared to fix any problem I can. I have had previous trailers with all PEX lines and never had any leaks. (End of rant)

I did also, knowing the likelihood of leaks down the road. I added a worm hose clamp to the braided tubing when upgraded the toilet to a Dometic 310.

[Brother_Bluto]

It is the PEX fittings used for reinforced vinyl that will eventually leak... especially in cold weather. I have yet to find a manufacturer of PEX crimp fittings (i.e. barbed) that will certify they are compatible with reinforced/braided vinyl. The ID of reinforced vinyl is slightly larger, and requires more defined barbed fittings made for vinyl (with a screw clamp). I have also yet to find a true vinyl barb to PEX crimp transition fitting which leaves using a threaded vinyl barb jointed to a threaded PEX crimp fitting for a proper transition... or just get rid of the reinforced vinyl altogether.

FWIW - there isn't a "soft" and "hard" PEX. There are two main potable-water types of PEX - PEX-A and PEX-B. Both are sold in coils or as sticks and no difference between one version in a stick or that same version in a coil. PEX-A is easier to work with IMO as it a bit more flexible, less prone to leak from a kink and has less memory. Both PEX-A & B can use the PEX brass or plastic crimp fittings & push to fit fittings... but only PEX-A can be used with Uponor-style expansion fittings.

[Scott'n'Wendy]

Fittings that rely on an o-ring to seal, such as SharkBite brand and similar, are not certified for use on braided tubing. Barbed fittings with pipe clamps (worm gear, even PEX clamps) are about the only reliable connection. O-ring fitting MIGHT be made to seal, but the seal will not be reliable for the long term, especially with vibration.

The worm gear clamp on factory RV braided hose is at best a temporary measure-they will also leak. They are mated to pex fittings. The only reliable connection would be to change the fitting or the hose and then use the correct clamp...depending on which route you took.

I agree with what you say. If you are doing more than changing "like for like", make sure you know what you are doing or call a licensed tradesman.

PS..I have grown to hate the title "Tech". It's thrown around like a catch-all for anybody servicing any machine/appliance/vehicle/trailer/blender. Proven training? You may have lots...or a little. I have a friend who told me a few years ago. "Hey! they call me a tech now. Don't know what's different between yesterday and today though. lol"