Community Forums

Jager · 08-14-2015, 08:57 AM

SoI top off the fresh water tank with 105 gallons of water. I know it is full because
1) The gauge tells me so
2) I can see the tank from the water bay
3) water starts to come out the over fill (over flow) tube

I leave it sit over night and leave for trip the next day. I do have to go through some good sized hill and curvy roads. I arrive at camp ground and now there is only 75 gallons of water in the fresh water tank?

Water pump was off entire time. Black and grey tanks are still empty. Nothing is wet and there are no signs of leaks any place in the coach or basement.

Where did the 30 gallons of water go?

The only thing I can figure is that it was lost out the over flow tube while sloshing around on the drive to the camp ground. Can you really lose that much water just from that? Is there a way to close that port/tube so you don't lose water while driving? Do I have a switch or dial set incorrectly?

Anyone else experience this?

racer0624 · 08-14-2015, 09:09 AM

If it's like my '09, it siphoned out of the over flow. I put a clamp on it when I left with a full tank.
John destin fl
2015 LADP

Mike and Cha · 08-14-2015, 09:16 AM

If you leave the tank about an inch or two below full it won't do that. The first time I filled my tank the whole way I experienced the same thing. I then read on IRV2 about how the water will siphon off, and people recommended adding valves/clamps ect. I just don't fill it all the way to the top and it's never done it again.

Jager · 08-14-2015, 09:27 AM

Thanks. I will have to see what my options are for clamping or adding a valve.

I'm amazed at the amount of water that I lost. I would have expected a few gallons maybe until the level worked its way down but 30 gallons? Didn't see that one coming.

Thanks again.

"007" · 08-14-2015, 09:38 AM

If its possible redress the over flow higher from top of water tank or do not over fill as suggested.

GaryKD · 08-14-2015, 09:47 AM

Hi Jager,
Consider not making this more of a project than it needs to be. Mike and Cha posted what I do and you should seriously consider. The tank will hold more than 105 gallons. Leaving about an inch from the top open you will have the advertised 105 gallons, most likely more.

TeJay · 08-14-2015, 10:05 AM

This is an ongoing issue with several manufacturers. We have this with the WBGO. There are several fixes which may work but for most the fixes, especially those suggested by the manufacturers don't work. On individual with a 2014 Vista 30T by WBGO relocated the overflow tube by drilling holes in the coach floor right above the tank and routed the overflow tube up through the floor and back down and out the bottom. That raised the overflow route way above the height of the tank and stopped the siphoning effect.

That is a sure way of fixing the problem. For some getting it above the tank by going through the floor because of location may not be practical.

Some manufacturers just said to install a larger tube around the overflow elbow so air could get in and that would stop the siphoning. That didn't work either as reported by several.

Don't know why a simple check valve would not work. One can install a shut off valve on the overflow tube but you have to remember to open it when you fill and close it when you travel. It never fails and I know that will be forgotten from time to time so I don't like that idea either.

What Mike and Cha mentioned may work for some or most but I guarantee it won't work for all. Each coach and manufacturer is slightly different and one fix is not a fix for all. Now if you only fill your tank to 1/2 or less yes that would probably work. If one is dry camping in the desert for a long weekend you want all the water you can carry so that won't work. Each case and circumstances are different.

The absolute most fool proof method is to raise the overflow outlet well above the tank. Again I don't know why a check valve would not work. I think that a check valve would at least resist water flow more than just an open tube.

If I had this issue And couldn't raise the flow tube level I'd install a check valve as close to the overflow elbow as I could. Then install a shut off valve further down the overflow tube and shut it about 75% of the way. The check valve would resist water flow but not air flow and the shut off valve would restrict water flow but still allow air flow. It may not be a complete fix but would be trouble free, and keep the water loss to a minimum I think.

Don't fill the tank until you get close to where you are going is one choice. For most that will work but for some who dry camp a lot that won't work or at least it's not as convenient. We like our own water to use, drink while we are away for an extended weekend.

Many choices. Determine which is best for your situation.

TeJay

jrwitt · 08-14-2015, 10:28 AM

One thing to think about if you put a shutoff valve on the overflow line. If you fill your tank with cool water then shut off the valve, the water will expand due to warming and build up pressure as you drive especially if you are in a hot climate. Don't know if it could build up enough pressure to break something, but worth considering. If something did break, it would most likely be the weakest point in the system such as a plumbing fitting at a tee or going to a faucet. Perhaps you could install a pressure-relief valve similar to the one on a hot water tank? Just a thought. Maybe someone out there with more knowledge of the subject can add their comment on this.

Arch Hoagland · 08-14-2015, 10:32 AM

I'm curious why you carry 100 gallons of fresh water.

Is there no water at the place you go to?

allynne · 08-14-2015, 10:42 AM

Tom I have had this problem with both my DS and now my Mt. Aire my fix is when water starts coming out of the overflow I shut off the incoming supply then use a spring clothespin to seal the overflow tube after folding it several times. Result no loss of water. don't forget to remove after using a few gallons of water, certainly before adding more water. Not rocket science, don't make it more of a project than necessary. I firmly believe in the "KISS" principle.

Al Sawyer
'05 Mt. Aire

Dutch Star Don · 08-14-2015, 10:52 AM

"Jager"....I like to keep things simple and not have something else I have to worry about. My Dutch Star was doing the same thing. On the Dutch Star there is a peg board wall hiding the holding and fresh water tanks (passenger side). Often you can see the overflow hose by looking over the pegboard wall.

The problem is that the overflow hose comes out of the tank and immediately curls over and goes through a hole in the floor. Once the water sloshes up into the overflow, it creates a syphon and the water will flow out. It will do this several times until it gets to a level where it stops.

I found on mine, there was still several inches of height above the curl in the hose. I added about 12" more hose (available at Lowes or Home Depot) and extended the hose higher into the bay, until it touched the ceiling and then routed it back down through the hole in the floor. This additional height was enough to stop the syphoning.

slowmachine · 08-14-2015, 10:55 AM

Quote:

Originally Posted by jrwitt

One thing to think about if you put a shutoff valve on the overflow line. If you fill your tank with cool water then shut off the valve, the water will expand due to warming and build up pressure as you drive especially if you are in a hot climate. Don't know if it could build up enough pressure to break something, but worth considering. If something did break, it would most likely be the weakest point in the system such as a plumbing fitting at a tee or going to a faucet. Perhaps you could install a pressure-relief valve similar to the one on a hot water tank? Just a thought. Maybe someone out there with more knowledge of the subject can add their comment on this.

One physical property of water, that makes it very useful for defining units of measure (for example, one liter of water is one kilogram) is that it does not expand and contract when heated and cooled, and it does not compress under pressure. So no, the volume of water in the tank does not expand when it gets hot. The pressure-relief valve on a hot water tank helps prevent the water from boiling and producing steam (which does expand) but still allows for venting to prevent rupture of the tank.

Mike
2000 Holiday Rambler Endeavor 40PBD
Freghtliner XC, CAT 3126B

Tony Lee · 08-14-2015, 11:08 AM

Quote:

is that it does not expand and contract when heated and cooled,

What?
Not what we were taught in Science class.

Quote:

liter of water is one kilogram

also not true.

Tony Lee · 08-14-2015, 11:16 AM

One physics property that is true is that a column of water approximately 2' high exerts a pressure of approximately 1 psi on the bottom of the container. This means that if you extend the overflow pipe up 2' above the top of the tank, the pressure inside the tank will be more than 1psi and that acting on the large top and bottom of the tank will exert a pressure of many hundreds of pounds on any structure above and below the tank.
If you also fill the tank rapidly either from the mains fill or through a hose shoved down the gravity fill pipe, the resulting pressure in the tank can result in forces of several tons acting on retaining straps and any part of the structure in close contact with the tank.

I think you should all keep hassling the RV buildrrs about this problem. The complete cure is not rocket science and after 50 years of building the same water system that does the same thing, its time they stepped up and solved the problem they create by shoddy engineering.