Thought I would post this for others to reference.
Had lowish water pressure for some time when on mains pressure, checked the system but found nothing amiss. During the last few days have had a vibration sound coming from the filling point. Having removed the filling fitting, found an "O: ring had come away from its position.
What is interesting, is that I was led to believe that this was a filter, but that is not the case. It is a non-return valve. So why have another non-return valve in the same line, i.e. a non return valve is also inside the "Pressure limiting valve".
So out with the drill and removed the plastic internals of the valve. Now we have better water pressure.
The non return valve is there so when you switch the pump on the water doesn't come out the mains inlet. You can also replace this valve with a John Guest or similar placed behind the inlet fitting. Usually poor flow is caused by the pressure limiting valve- a common problem for Jaycos.
The pressure limiting valve reduces the mains pressure down to I think 350 kpa from what I can gather, some places have very high water pressure up as high S 900KPA so I have been told ,that would bow your P/r valve and weaken your plastic pipe work until that gives way as well,I hnow we had silastic under the seat of our Preassure limiting valve ,from bad assembly they used silastic on ours instead of thread tape and it got under the valve seat, as well as the threads ,and left us without five trips back to manufacturer through heavy traffic to eventually trace it myself and fix it...
Just to clarify, the inlet fitting has a non return valve built in, made of plastic, it is before to pressure limiting valve, which also has a built in NRV.on the 350 kpa model.
Our 350 kpa pressure limiting valve is the first thing on the outside of the van that you connect your water hose too ,our pressure release valve is inside our water heater accessible from outside of the van.others may have there things in different spots our van is a nova.