I have a Jayco Heritage 2004 which I purchased second hand.
This has just happened on this trip we are in a CP we are main pressure it is now filling the front tank and over flowing.
I noticed that the gauge inside showed full we left home with it empty. I have the tap underneath the van on however is there a non return valve that should not fill the tank when on mains?
Over the last several trip we have only used the tanks with no mains. I now have turned the tap off to the tank and it seems OK should there be the non return valve or could it be stuck. Not a great problem just annoying.
Oh boy another one! a while ago the complaint was people couldn't fill their tanks, now the tanks are filling by them selves, and still they complain, you just can't keep people happy.
Sorry I would not have an answer for you
Never owned an Jayco caravan
I can only advice you to pop in by one of the Jayco dealers they would for sure know the answer
and otherwise one of the caravan repair shops
Problem solved with water going to the tank whilst on the mains pressure.
Put caravan in to my service people for a small problem and mentioned that it was recommend that I put a 500 pressure limiting valve as my pressure was a bit low this was another caravanner with a Jayco Silverline and he has done this and it was better.
Got the caravan back and the pressure from the tanks is great also the noise that the pump made which was loud had been reduced greatly, they also put a non return valve on the tank and I believe there is one on the valve.
They found my valve had gone to heaven.
iana I am putting this up so newbie my find it help full.