Fresh water overflow tube question

Javin · 08-01-2020, 12:45 PM

I have been meaning to address this issue for a while. When ever we fill our fresh water tank, before its full the over flow tube underneath the trailer starts gushing water. To make matters worse I had to back into a steep incline which seemed to make more water come out of the overflow tube. A guy who was in line to fill told me he capped his overflow tube to prevent this from happening.

Is it ok to cap this tube in order to prevent a days worth of water from leaking out after filling the tank? If so what would you use to cap it? Not sure if it is left uncapped for a reason, perhaps air flow? Or did they just forget to cap mine??

bankr63 · 08-01-2020, 01:50 PM

Yes, the hose should remain open when using the tank, it is the primary way for air to reenter the tank as water is pumped out, although it can also come down the fill pipe if the seal isn't tight.

On my 19H the overflow comes up off the top of the tank and U's back down through the floor right beside the pump. Would probably be pretty easy to just splice a shutoff valve into the pex there.

TaftCoach · 08-01-2020, 02:06 PM

There is a siphon affect that causes the overflow to behave that way.

If you do cap it off while filling remember the air has to escape somewhere so you may need to fill more slowly so it can escape via the gravity inlet.

Colorado · 08-01-2020, 02:47 PM

I just added a PEX valve to the overflow valve line, outside of the trailer. I also made a laminated sign, Reminding whoever turns on the pump to open the valve. Why the sign? Because it’s not worth the argument...

I open it for filling and during use, I simply close it during traveling.

**JFlightRisk** · 08-01-2020, 02:55 PM

I put 1/4 turn valves on the ends of out over flow tubes. Open to fill, close to move, and re-open when leveled up. They work well.

Javin · 08-02-2020, 09:05 AM

Thanks for the info gang. So when filling the tank leave it open untill it starts over flowing and then close it to finish filling and when travelling. However once you are parked if you open it right away it will start coming out i'm guessing unless you wait for some of the water to be used.

Can someone tell me what exactly would happen if you left it closed while running the water inside the trailer? Would the water simply not come out of the tap or could it damage the pump?

RetiredOne · 08-02-2020, 09:31 AM

Quote:

Originally Posted by Javin

Can someone tell me what exactly would happen if you left it closed while running the water inside the trailer? Would the water simply not come out of the tap or could it damage the pump?

Without a vent, you risk the pump sucking in and collapsing the tank. When water flows out, air needs to flow in.

Javin · 08-02-2020, 09:58 AM

Quote:

Originally Posted by RetiredOne

Without a vent, you risk the pump sucking in and collapsing the tank. When water flows out, air needs to flow in.

Yikes! that would be bad. So I guess some water spilling out once parked is inevitable if you open the valve once parked and the tank is full.

Javin · 08-02-2020, 11:41 AM

I am surprised no one has found a hack to allow air in but no water out. Not sure if this is technically possible but would be nice.

RetiredOne · 08-02-2020, 04:59 PM

Quote:

Originally Posted by Javin

I am surprised no one has found a hack to allow air in but no water out. Not sure if this is technically possible but would be nice.

Actually, there are a few. Some people have taken the vent and overflows and put a loop in them, and claimed it stop. Others have taken those hoses, and ran them up higher than the tank, then back down, and claimed it stopped. Might be worth a experiment.

Javin · 08-02-2020, 06:52 PM

Quote:

Originally Posted by RetiredOne

Actually, there are a few. Some people have taken the vent and overflows and put a loop in them, and claimed it stop. Others have taken those hoses, and ran them up higher than the tank, then back down, and claimed it stopped. Might be worth a experiment.

Cool, hopefully someone chimes in with some ideas.

madmaxmutt · 08-02-2020, 07:33 PM

Quote:

Originally Posted by Javin

I am surprised no one has found a hack to allow air in but no water out. Not sure if this is technically possible but would be nice.

I have had some success "burping" my tank.
Remove the hose.
Turn the fill/city valve back and forth waiting 5-10 seconds between turns.
You can literally hear the pressure change at the inlet.
Once I have done that a few times, I put it back to tank fill.
Then, I turn on the pump to pressurize the system.
This has stemmed the flow of water out the tube my last three trips.

It only seems to work if you slow down the fill towards the end. If you fill too fast when the suction starts, it will gush out and there seems to be not stopping it.

pconroy · 08-02-2020, 09:03 PM

When mine overflow, I stop filling and immediately turn on the outside shower until the overflow stops. That stops the siphoning effect for us.

Colorado · 08-03-2020, 08:31 AM

Quote:

Originally Posted by Javin

Thanks for the info gang. So when filling the tank leave it open untill it starts over flowing and then close it to finish filling and when travelling. However once you are parked if you open it right away it will start coming out i'm guessing unless you wait for some of the water to be used.

Can someone tell me what exactly would happen if you left it closed while running the water inside the trailer? Would the water simply not come out of the tap or could it damage the pump?

You can simply remove or loosen the “fill cover” to allow air flow during your initial usage. This system is far from air tight and the possibility of collapsing the tank although yes it’s a potential problem it’s hardly an absolute because you’re not running the pump nonstop. The intermittent use allows air to seep back into the tank. If we stop to use the camper i.e bathroom breaks on the road I don’t open the valve or worry about it.

You will lose a few ounces of water when opening the valve because the water is already in the overflow line. You could catch those few ounces if you’re worried about them and use them in the toilet. As I mentioned above also, I put a note by the pump switch just to remind us to open that valve once we’re set up at the campsite. After a few times of camping with that valve on your overflow line it will become second nature to open it just like leveling your camper or putting out your awning.

Javin · 08-04-2020, 01:52 PM

As someone who is not versed in putting in a shut off valve i was wondering is there a preferred method of doing this? Not sure what exactly to buy in order to install something on my 16XRB. Preferably something not too difficult to install.

madmaxmutt · 08-05-2020, 11:01 PM

Quote:

Originally Posted by Javin

As someone who is not versed in putting in a shut off valve i was wondering is there a preferred method of doing this? Not sure what exactly to buy in order to install something on my 16XRB. Preferably something not too difficult to install.

There are a couple of different hose types. Posting a picture of yours might help. Mine looks like a bicycle inner tube. Colorado posted a pex tube picture above.

Javin · 08-06-2020, 08:59 AM

Quote:

Originally Posted by madmaxmutt

There are a couple of different hose types. Posting a picture of yours might help. Mine looks like a bicycle inner tube. Colorado posted a pex tube picture above.

Heres some pics of my overflow tube. Looks like I don't have much room as its quite short compared to the pics others posted. Any advice on what to install would be great.

**JFlightRisk** · 08-06-2020, 09:19 AM

You could extend that a little with a straight barb fitting, another short length of hose, then the valve.

Something like this:

https://www.homedepot.com/p/Everbilt...0069/300096242

bankr63 · 08-06-2020, 12:08 PM

Quote:

Originally Posted by Javin

Heres some pics of my overflow tube. Looks like I don't have much room as its quite short compared to the pics others posted. Any advice on what to install would be great.

What the heck is that hose hanging down below the tank? Is that your overflow line too? Very sloppy having it hang down like that. On my 19H, the overflow is on the top of the tank, and comes directly up through the floor then loops back down and out beside the tank.

JimD · 08-06-2020, 01:05 PM

I extended the hoses using Pex tubing up into the outside shower/water fill cabinet. Just punched a hole in its bottom and ran the tubing with valves up against the wall. Since this cabinet is waterproofed it seemed like a good place to put it.

Previously when I had my valves on the bottom edge of the rig I would be filling the tank in the cabinet while having to constantly stare down the side waiting for water to come out and then rush to shut the valves and turn off the hose. Now it is right there in front of me. When filling I have a shutoff valve attached to the hose end so I can easily start/stop or lower the filling speed.

My previous valves were located low and under where the slide came out which made it inconvenient to get to. This is one reason it was easily overlooked. So much easier to get to now. I think I can drive with one valve open and not worry about any siphoning.

Here is a link to another thread on the same subject.
https://www.jaycoowners.com/forums/f...tml#post883841

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