Chris Bryant wrote:
have seen this failure, but I suspect it is due to stress on the valve from misaligned inlet tubing.
Chris ... I think that is EXACTLY what's going on in my situation.
The stiffness of the PEX - combined with it's non-aligned-angle attachment to the plastic fresh water valve's male connector is what I think is causing the stress cracks in this complex and (overly) deicate molded plastic Tetford fresh water valve assembly. The leaks in my valve assembly are so micro-small that the leaking fresh water is exiting not only as very slow drops ... but as vaporized water! I can see white vapor smoke escaping into the air around the valve assembly while the water pump is pressurizing the lines!
Not only did Winnebago angle the incoming PEX line less than ideal, but I feel that the Tetford valve design is not really the best from a reliability standpoint. As I said earlier, it looks like the valve supplier changed the material type between my original and first replacement valve assembly - but it's still not optimized. Brass or stainless steel would probably be the best valve materials ... but the valve's necessary design is most likely too intricate for metal forming.
I guess that a 3rd plastic Tetford valve, a short piece of fexible tubing, and a shutoff valve is my best choice right now ... but I hate the downsides of a piece of maybe less long-lasting pressure tubing combined with the additional leak potential introduced with another valve in the system. A better PEX entrance angle might be an even better fix, but that means punching a(nother) large hole in my RV's bathroom wall.
Ultimately, I'm probably paying the price for a toilet in the rear of a small Class C motorhome on a stiff E450 chassis driven too much on rough roads.
