Fresh water tank magically fills itself.....

[WeRJuliian]

I'm seeing an odd phenomenon on our 19XUD.

The City Water connection is hooked up, so I'm not using the fresh tank.
Over a couple of days, the fresh tank is mysteriously filling itself.... I can drain it and, a couple of days later, it's 2/3 or more full again.

My best guesses are:

a) There's an unadvertised cross connection between the two, with maybe an isolator valve that's not fully closed, or leaking slightly.

b) There's a non-return valve, maybe on the water pump, which is faulty and allowing a slight backflow from the faucet side into the fresh tank.

c) Same as b, but backflow from the water heater.

d) There are little elves with tiny buckets, slowly filling up my tank at night, while I sleep.

Jayco's manual is predictably unhelpful... it doesn't mention anything about getting rid of troublesome elves, for instance... and it specifically says that the fresh tank cannot be filled from the city connection.

So I'm wondering if anyone has had the same issue...and, more importantly, fixed it?

Alternatively, does anyone have a reliable plumbing diagram for a 2017 19XUD, please?
As far as I can tell, access to the pump/valve area, requires dismantling one of the bench seats (there's a little "trapdoor" in the seat, but it's not much help.)

Any help, clues, guidance, would be most appreciated.

 

[Merrick-JAY]

I cant help, but on my 2017 19XUD, the whole plywood bench seat (including the trap door) lifts up to reveal all plumbing connections. Sounds like cross connection or bad (or not totally closed) valve. Let us know what you find out.

 

[Grumpydad]

Leaky valve is my guess, but I'm hoping it's elves. That would be awesome.

 

[Mustang65]

I am not totally sure, but there is either a one way valve between the fresh water pump and the hook up to the TT plumbing, or the water pump has an internal one way valve. I am sure, but one of the more plumbing technical members will help out here.

You may be able to check if that is your problem by opening the valve by the water pump that has a hose on it for filling the TT plumbing system with antifreeze for winter. If you open the hose valve and close the valve going to the freshwater tank and you have the city water connected, the water will come out the hose, if the one way valve is defective or if there is none.

I am sure one of the members will verify this for me.

Don

My Registry

RVing with SOLAR

 

[o2silverado]

D is the only answer !
If you contact jayco they will send you plumbing schematics. I would guess it's a check valve in the pump.

 

[bdreinv]

X2 on the manual who ever wrote it, must have never owned a camper lol!

 

[Racinforthefinish]

On my Jayflight 23rb the water pump had a back flow preventer that stuck and let the fresh water tanks fill off city water. Clean it, whack it, or replace it, whatever works!

 

[Grumpy]

On my Jayflight 23rb the water pump had a back flow preventer that stuck and let the fresh water tanks fill off city water. Clean it, whack it, or replace it, whatever works!

Usually the problem.. Running the pump before you drain the tank may also help.

 

[Isaacs]

Close the valve between the pump and the fresh water tank. If that solves the problem, you'll know it's the check valve in the pump. As a workaround you could simply leave the valve closed 'till you get a chance to rebuild/replace the pump.

 

[Jim Davis-JAY]

I took a slightly different approach to this. I added a real check valve between the pump and the tank. Don't know for sure but it seems to be working fine.

 

[Isaacs]

I took a slightly different approach to this. I added a real check valve between the pump and the tank. Don't know for sure but it seems to be working fine.

Good idea. But I was just thinking...if the OP's check valve was bad, the pump would keep cycling trying to keep the pressure up; did yours do that?

Or maybe he never uses his pump?

 

[Jim Davis-JAY]

My pump seems to be fine but on a recent trip my tank filled while I was on city water. I disconnected and just used the pump and tank. I considered trying to find out what needed to be done and took the easy way out by putting a plumbing check valve in the line. I did put a one inch block under the pump to get the check valve more vertical.

 

[bankr63]

Good idea. But I was just thinking...if the OP's check valve was bad, the pump would keep cycling trying to keep the pressure up; did yours do that?

Or maybe he never uses his pump?

The pump wouldn't need to be on because it is on city water. The system is pressurized.

My concern with adding a check valve on the back side of the pump is ensuring that you are using pressure rated pex pipe or similar between the valve and the pump. If the valve inside the pump is leaking, the hose back to the new check valve will start to pressurize. If you just used the clear poly pipe that they tend to put on the siphon (non-pressure) side of the pump, it may burst once it starts to pressurize.

 

[Jim Davis-JAY]

My check valve is in PEX, not vinyl. I still haven't had the chance to check it totally, but it was good on a dry camping trip.

 

[Gizmopilot]

My new in May 2018 jayco 322rlok is doing the same thing, i will be taking it in for some warranty work and this is on the list.

I will share what they say it is after I get it back in Mid December

 

[norty1]

Read this thread: https://www.jaycoowners.com/forums/f18/water-dumping-62962.html#post706586


Sounds similar.

 

[davolson-JAY]

Have to agree with the thread referenced by norty1. Our 2018 28.5RSTS did the same thing, found the tank to be mysteriously full . I believed that I had inadvertently bumped the pump on possibly more than once, while hooking up to city water. Without being under pressure, the pump check valve was not fully closed. In subsequent hookups ran a bit of water from the fresh tank with the pump, shut it off, then hooked up the city water. Hasn't happened again. I may not completely understand the plumbing hookup.. but in the next half dozen stays, it didn't do it again.

 

[Usmade56]

My first coach was a pace arrow and I had same problem. It was water pump. Replaced and no more fresh water tank over flow. This was 11 years ago, I was newbie and can't remember why.