There are two (were) in our van, one was incorporated in the pressure limiting valve, and the other was inside the mains pressure inlet fitting. I had trouble with the NRV in the pressure limiting valve, so dismantled it and cleared the offending piece of sand. We had a loud humming noise coming from the inlet fitting after that, and found the seal had partially come off the valve there. I could not get the seal back on, and couldn't see why we needed two valves, so I drilled the guts out and removed that valve. We have no problems with water leaking out of that connection when using the inboard pump.
There are various "Pressure Limiting" valves available, but the one for caravans, as fitted to our van, is set at a lower pressure, and has the NRV incorporated in it, others are designed for household use, and have a higher pressure setting, those do not have NRV fitted in them. I know Jayco sell two types of this valve, and perhaps the other type does not have a NRV incorporated.
So I can only assume the valve you have fitted does not have the NRV, and with the replacement of the inlet connection all is good.
PS I would keep a spare if I were you, if the seal comes off that valve, you may be in trouble again.

Long Weekend wrote:

---

Jayco use the John Guest type of plumbing fittings. Sometimes all that is required is to push the pipe more firmly into the fitting to seal it.
I have had that happen once to our van and a friend's 'A' frame tap.

Murray

---

 I have found that over time the John Guest connectors may fail due to the hardening & slight distortion of the pipe at the fitting.  Often caused by the failure to fit a pipe support insert into the pipe at the join.  Solution easy if you can cut off a bit of pipe & refit using the pipe support insert.

Another case of poor workmanship by our Aussie Caravan manufacturers.

I went through my whole plumbing installation and fitted the pipe support inserts (& some missing locking clips), for just a few dollars.  I had trouble getting replacement 'O' rings though, John Guest don't sell them, but Reece came good as usual.   Just another of the maintenance projects that I tackle when the van is up on blocks at home.  Drew up a schematic diagram of the plumbing in the process.  Mighty come in handy one day.  I just enjoy pottering about under or on the van dreaming of being out on a trip somewhere.

-- Edited by Cupie on Thursday 26th of September 2019 10:33:28 PM

I have had the same problem. New non return valve fixed it. Can be caused by dirt getting into the system. Mine blocked because mud dauber wasps blocked up my breather and some of their mud found its way into the valve.