Plumbing riddle

[gccch]

I had an electrical question resolved earlier, now for a plumbing issue.

We are at a CG currently hooked up to the water supply. But we registered late and they did not have a space for us for the next one or two nights, so we will be boondocking in a field. In preparation, I want to fill the on board water tank. So I turn our fill valve from “normal” to “tank fill” as detailed in the manual. The tank fills, and signals full by the overflow tube outflowing water, and the gauge reading full. I turn the valve back to normal and I’m doing dishes with the park water, expecting my tank to remain full. Later I check the levels and fresh water is showing one third full.

This is when I noticed the overflow continues. I went and filled the tank again, same process, and noticed the overflow tube continues to flow for 20-30 minutes! Again, the gauge had read full, now reads 1/3.

I would really like a full tank. Any ideas?

[slickest1]

Are you sure it is the overflow and not the tank drain.

[MSHappyCampers]

This is called "siphoning" and is pretty common. When you shut off the water clamp the overflow tube closed for a minute or so.

[TonyDi]

If you are sure it is your overflow tube, then you most likely have developed a siphon that's draining the tank. Check to see if the hose has sagged. I cure mine by making a small hole in the overflow tube so a siphon can't start.

[gccch]

Ok, good tip on making a hole. I have filled it and watched the gauge to full and shutting off the fill before it overflowed. That seems to get me most of the way to full. I will investigate the permanent fix when we get home.

Thanks again for the excellent advice!

[Tony Lee]

Just another trivially-simple engineering problem that the RV designers have never managed to solve. Their philosophy seems to leave lots of annoying things for the owner to solve so that people don't develop an unhealthy appetite for good quality engineering

[FIRE UP]

Originally Posted by gccch

I had an electrical question resolved earlier, now for a plumbing issue.

We are at a CG currently hooked up to the water supply. But we registered late and they did not have a space for us for the next one or two nights, so we will be boondocking in a field. In preparation, I want to fill the on board water tank. So I turn our fill valve from “normal” to “tank fill” as detailed in the manual. The tank fills, and signals full by the overflow tube outflowing water, and the gauge reading full. I turn the valve back to normal and I’m doing dishes with the park water, expecting my tank to remain full. Later I check the levels and fresh water is showing one third full.

This is when I noticed the overflow continues. I went and filled the tank again, same process, and noticed the overflow tube continues to flow for 20-30 minutes! Again, the gauge had read full, now reads 1/3.

I would really like a full tank. Any ideas?

Well,
First off, if it is in fact the over flow tube, I'm amazed the manufacturer set the over flow system up so that it would siphon TWO THIRDS OF THE TANK before it quit. Somethings amiss here. On our coach, an '04 Itasca Horizon, 36GD with the C-7 330HP CAT, has a 90 gallon fresh water tank and, yes, when fill it to the brim, it will siphon off about 3-4 gallons, MAYBE, then it quits. The tank level still reads full.

Second, is this the first time this has happened? How long have you owned the coach and, have you never filled the tank to capacity before this? Just wondering what kind of history on this issue. The reason I ask is, something may have changed, fallen, (overflow tube maybe) etc.

Scott

[gccch]

Originally Posted by FIRE UP

Well,
First off, if it is in fact the over flow tube, I'm amazed the manufacturer set the over flow system up so that it would siphon TWO THIRDS OF THE TANK before it quit. Somethings amiss here. On our coach, an '04 Itasca Horizon, 36GD with the C-7 330HP CAT, has a 90 gallon fresh water tank and, yes, when fill it to the brim, it will siphon off about 3-4 gallons, MAYBE, then it quits. The tank level still reads full.

Second, is this the first time this has happened? How long have you owned the coach and, have you never filled the tank to capacity before this? Just wondering what kind of history on this issue. The reason I ask is, something may have changed, fallen, (overflow tube maybe) etc.

Scott

We have owned the MH since September and have not had the need to fill the fresh water tank until now.

[FIRE UP]

Originally Posted by gccch

We have owned the MH since September and have not had the need to fill the fresh water tank until now.

gccch,
Thank you Sir for getting back here with that. Even though it's not mine, I'm still at odds with the fact that the mfg of your coach potentially built an overflow of the water tank, that would drain 2/3s of it. I don't know how accessible that overflow is but, I'd definitely try and get to it, to do some investigation. We've headed out many times with a full water tank. We do it for two reasons. 1, we've broke down before and needed water for a few days. 2nd, if we know we're remote camping, and for a given amount of time, the tank is filled. Never been too worried about the weight.
Scott

[530ktm]

Originally Posted by gccch

I had an electrical question resolved earlier, now for a plumbing issue.

We are at a CG currently hooked up to the water supply. But we registered late and they did not have a space for us for the next one or two nights, so we will be boondocking in a field. In preparation, I want to fill the on board water tank. So I turn our fill valve from “normal” to “tank fill” as detailed in the manual. The tank fills, and signals full by the overflow tube outflowing water, and the gauge reading full. I turn the valve back to normal and I’m doing dishes with the park water, expecting my tank to remain full. Later I check the levels and fresh water is showing one third full.

This is when I noticed the overflow continues. I went and filled the tank again, same process, and noticed the overflow tube continues to flow for 20-30 minutes! Again, the gauge had read full, now reads 1/3.

I would really like a full tank. Any ideas?

Stupid design and mine would do the same thing (2014 Itasca Sunova) but maybe not drain as much as you are saying. I installed a valve in the breather tube or over flow tube. I open it when filling tank, you must not forget to do this, and close it when full and hitting the road. This has worked perfectly for a couple of years.

[gccch]

Originally Posted by 530ktm

Stupid design and mine would do the same thing (2014 Itasca Sunova) but maybe not drain as much as you are saying. I installed a valve in the breather tube or over flow tube. I open it when filling tank, you must not forget to do this, and close it when full and hitting the road. This has worked perfectly for a couple of years.

Sounds like a really good solution!

[Dutch Star Don]

"gccch".....On a side note, filling your tank until it runs out the overflow is NEVER a good idea. It's possible that the incoming water pressure can be higher than the outgoing (overflow). Overfilling it can cause it to swell and break hold down points or even rupture. You take a chance of cracking plumbing joints too!

[jfran304]

If you had your water pump on when you were washing the dishes it will use the water out of your fresh water tank even if you are hooked up to the camp water supply.

If we are at a campground with poor water pressure we will turn on the water pump to supplement the water pressure when we take a shower. This will use the water out of our fresh water tank.

You can not depend on what the gauges say.

[530ktm]

Originally Posted by jfran304

If you had your water pump on when you were washing the dishes it will use the water out of your fresh water tank even if you are hooked up to the camp water supply.

If we are at a campground with poor water pressure we will turn on the water pump to supplement the water pressure when we take a shower. This will use the water out of our fresh water tank.

You can not depend on what the gauges say.

I agree with you, however this is not what his problem is when it comes to the tank losing water out of the overflow tube.