Water Tank Fill

[cummins2014]

I seldom need a full tank of potable water, usually 10-15 gallons to use if needed while traveling . The one time I wanted a full tank , unlike my older fifth wheels that had the fill port on the side of the trailer ,stuck a hose in it ,and filled it ,when it was full it overflowed out of the port . This fifth wheel has the tank fill valve setting on the water hookup , dry camping ,city water etc.

The problem is when filling it ,the only way to know its full besides watching the gauge is that it starts running out the overflow lines , I have two one on each side . It's seems to run an excessive amount of water out those lines, was told if I wanted a truly full tank of water ,plug those lines when it starts to run out of them, Well that's a bit awkward under there. Another option I guess would be to install some shutoff valves , that's a bit dangerous if they were to be forgotten if kept shut when filling up the next time .

My son just experienced the same thing ,his drained back to 2/3 full on his new fifth wheel. Not sure what the solution is ,but I would have to guess there is some procedure to get a full tank of water without losing a large amount of water out the overflow. Any thoughts of what we are doing wrong, or is that just the nature of the beast . I wait until I see it start to run out the overflow, and shut the water off immediately , but it still drains a lot of water out of there.

[JRscooby]

cummins2014 wrote:


Thanks.No idea how it’s plumbed up in there , without pulling the belly off . I have a feeling on my sons it’s what you say , runs a lot of water out of there when it’s full , will have to address it. It reads full at first , but after it quits out of the overflow, as said it’s 2/3. With a 56 gal. tank , he’s losing approximately close to 20 gals .

Don't bet much on what I say. I have used siphons to move lots of stuff, fuel, oil, water and even molten pot metal.
But I'm just guessing what is happening, others might have better idea.

[MFL]

Not sure if you told me what FW your son purchased. If you don't mind posting what brand/model, someone here may have same, and will respond, if they had similar issue and the fix.

Hope he is happy with his new truck!

Jerry

[cummins2014]

JRscooby wrote:
Extending the overflow up will not change much. I would check the overflow does not extend down inside the tank. If it does, and you fill until it comes out the overflow it will run out down to the end of tube, no matter how high it must go. If that is the issue, and can't fix inside tank. Tee into the top of overflow line, extend up a few inches, then daylight. This will break the syphon, keep tank full.

Thanks.No idea how it’s plumbed up in there , without pulling the belly off . I have a feeling on my sons it’s what you say , runs a lot of water out of there when it’s full , will have to address it. It reads full at first , but after it quits out of the overflow, as said it’s 2/3. With a 56 gal. tank , he’s losing approximately close to 20 gals .

[JRscooby]

Extending the overflow up will not change much. I would check the overflow does not extend down inside the tank. If it does, and you fill until it comes out the overflow it will run out down to the end of tube, no matter how high it must go. If that is the issue, and can't fix inside tank. Tee into the top of overflow line, extend up a few inches, then daylight. This will break the syphon, keep tank full.

[ACZL]

Our Big Country has the overflows coming thru the frame as well and when we do need to fill/haul full fresh tank, I fill it iill water flows out, shut of water from house and away we go. Don't loose any or perhaps just a little, but still arrive at CG some 100 miles away w/ full tank (60 gal). Unable to fill tank at CG, hence having to fill at house.

[cummins2014]

MFL wrote:
I don't know from experience, but what jdc1 suggests makes sense to me. I would not plug overflow lines, I'm sure you know, that's not best option.

I often fill my tank full, and need every bit of it, but mine is the simple gravity fill tank.

Jerry

Yes ,a shutoff valve is asking for trouble on this system ,it fills thru a connection to the outside water supply, that water pressure will need to go somewhere when the tanks gets filled. I can only imagine bad things happening .

I like this method of filling ,just switch that Andersen valve to tank fill ,and away it goes . I have been cautioned that switching that Andersen valve under pressure can blow an o-ring, so I take the pressure of , which reguires shutting off the water supply, and just opening a water valve or outside shower ,and relief the pressure then switch the valve ,and turn the water back on to add water to the tank . Not a big deal .

[cummins2014]

jdc1 wrote:
Extend the overflow hose a few inches above the fresh water tank. That's how it should have been from the factory.

Thanks .Hard to tell at this point, they are running parallel , coming out thru a hole in the top of the frame just below the floor . So I am assuming they have to be elbowed out of the top of the water tank a couple inches , and run to the outside of the frame to drain the overflow . Unless they are plumbed into the side of the water tank at the top of the tank .

Only way for me to know would be to pull the underbelly ,and take a look . For me this not a great issue , but my son would like to be able to haul a full tank when boon docking ,considering his tank is only 56 gallons .

[MFL]

I don't know from experience, but what jdc1 suggests makes sense to me. I would not plug overflow lines, I'm sure you know, that's not best option.

I often fill my tank full, and need every bit of it, but mine is the simple gravity fill tank.

Jerry

[jdc1]

Extend the overflow hose a few inches above the fresh water tank. That's how it should have been from the factory.