City water filling fresh tank

wnjj wrote:

Farmboy666 wrote:
I did answer where the valve is, it’s on the line going into the tank. I only have one line going into and out of the tank. It has a ball valve, when I want to fill it I hook up a hose and fill it, when it’s full I unhook or turn off the city water an it gravity feeds out of my tank to the pump. If I want to use city water I close the valve to the tank to stop it from filling and use city water pressure. That about as plainly as I can explain. One line to my tank with a ball valve.

One more try and then I give up. One line and a ball valve doesn’t explain it enough. Where is the pump connected? Obviously the pressure side of the pump connects to the pressure side of the system but where does it get it’s input? From a tee in the line with the ball valve? On the tank side or other side of the ball valve on that line? Directly from the tank (though you said there’s only one line in/out)?

Simply saying there’s a line from the city water inlet to a ball valve to the tank doesn’t leave any more fittings to connect anything to. At a minimum I’m assuming the city inlet has a tee that goes to the pressure side of the system and to one side of the ball valve.

Forgetting filling the tank for the moment and consider this: If you can switch between city water and using the pump without moving any valves, then your pump is in between the pressure side and the tank and CAN leak back if it fails.

The reason I’m pressing this is it appears your RV is different than every one I’ve ever seen described, uses less parts and is apparently immune to pump check valve failure. If so this would be a nice upgrade to these standard systems.

The standard systems have 2 different paths between the pressure side (city inlet) and the tank. One is the pump. The other is a piped connection with the fill valve in line. They are in parallel. So if you open the fill valve city water fills the tank (and the pump would just circulate water back into the tank if you tried to run it this way). With the valve closed, the pump OR the city inlet can build pressure, but that pressure can leak back through a bad pump. RV’s without a fill valve just have a graviy fill that connects directly to the tank. As a cheat on some of those you can poke the outside shower hose back into the gravity fill and now your shower valve becomes a fill valve.

Hopefully this discussion helps the OP to understand and locate his issue.

I guess I assumed that it was obvious there is a tee in the line. I also assumed that when I say I open the ball valve and it gravity feeds to the pump that you can figure out where the pump gets it's feed from. I don't know how else to explain it and I know it works. My original statement was if the check valve in the pump fails it cannot fill my tank because it's either already getting the water from the tank or the ball valve is closed and I'm on city water. I know plumbing can be hard to explain or understand sometimes. I have been building houses for 40+ years and started plumbing in the 70's so I have some experience. RV plumbing can be complicated and maybe the guy who plumbed mine was either having a good day or a bad day since it looks like I'm the only person in the US who has this system. Either way that's what I have and like you I'm giving up. Happy camping