Community Forums

Zogman · 05-18-2008, 05:20 PM

I just filled my my fresh water tank in my 02 8311 for the first time. When it got full, it started to pee out (2) overflow tubes at the back of the coach. It pee'd for a long time. So I drove the coach back to storage and I checked the water tank and it only registered 3/4 full. Any thoughts???? Thanks

Z

Zogman · 05-18-2008, 05:20 PM

I just filled my my fresh water tank in my 02 8311 for the first time. When it got full, it started to pee out (2) overflow tubes at the back of the coach. It pee'd for a long time. So I drove the coach back to storage and I checked the water tank and it only registered 3/4 full. Any thoughts???? Thanks

Z

Ross G · 05-18-2008, 06:22 PM

I had this same problem with my Surfside! I was told that on the National motor homes that some how if you overfill the tank too much, it will create a suction and you will lose a great deal from the holding tank. I wait until I see the first sign of dripping from the overflow tube and cut the water off immediately! I once lost 3/4 of a tank! I was also told that if you turn on your water pump and open a faucet it will also break the suction! Hope this helps!

Ross

Zogman · 05-18-2008, 06:58 PM

Thanks Ross. Sounds like a siphon....

I'll that a try next time. Thanks again.

Zoli

jerseyjim · 05-19-2008, 02:10 AM

Never heard of a "suction" problem...but when you fill the fresh water tank...the only way you know it's full is when it starts the overflow thing out of the drains.

My tank monitor remains on the "full" (green) light and I have no problems.

I almost never travel with a full water tank...all that weight. But have done so when driving to a local race track, where there are no services. I do, however travel with the tank about 1/4 full...for the bathroom. I've never used the tank for drinking. When traveling cross county, I have 4 or 5 gallon containers of water in the bathtub...just for drinking, if I (we) need to. Really comes in handy for that occasional cup of coffee on the road.

Zogman · 05-19-2008, 04:34 AM

I can understand Jim if you go and mostly use hookups, we rarely use hookups.. Most of our camping is in the desert or sand dunes where we ride our ATV's or state campgrounds where there are limited services. Now that we got this 31 footer, we fit in fewer state campgrounds which sucks. In the 11 years that we had our 27' Itasca, we used hook-ups 4 times. Water is necesary for us and I really hate wasting time filling up on the road if it is even possible with some of our destinations.

M&EM · 05-19-2008, 08:18 AM

Zogman,
My NRV rig has 2 freshwater tanks connected with small pipes to make them same as a one large tank. NRV has done this on several of their models.

What seems to happen is the overflow and vent arrangement between the two tanks allows the closest tank to the fill pipe to reach overflow level before the second tank is full. Beside overflowing and losing water from that tank, the second tank eventual receives water from the first tank as the water seeks a common level. By that time your gauge will indicate something less then full.

A lot seems to depend on the rate of filling and the levelness of the coach when being filled. A slow fill to the overflow point several times is more likely to get you the fullest capacity.

Bob Dopher · 05-19-2008, 09:11 AM

I had the same problem with mine. The overflow line creates a siphon which won't break until the tank won't collapse anymore. National's solution was to replumb the overflow line such that a siphon cannot be started. In other words, get a little PVC pipe, a "T" and leave the top of the "T" open to the air. I put a an elbow in mine and pointed the opening bach down, covered it with a bug screen and have been able to carry a full tank for dry camping ever since.

Zogman · 05-19-2008, 11:58 AM

Great information guys. I will see if I have access to the overflow line. Thanks a bunch.

jerseyjim · 05-20-2008, 02:52 AM

ZOGMAN: Of course, one does what one needs for the different kinds of camping.

You dry camp with a minimum of hookup camping.
I hookup camp with a minimum of dry camping.

Fine and dandy. And your comment about your larger rig being unable to fit into sites you've used before....that's a common thing. The bigger you get, you'll find campgrounds that will be unable to accomodate you. Here in New Jersey, when slideouts started being popular, some of the campground owners were "screaming"....no room, have to cut down trees, etc., etc....and even today, when making reservations at a place I've never been to...I ALWAYS tell them I've got a 34 footer with a slide and an awning. HATE to travel...then find out I cannot be accomodated.
But then...I sometimes find the SITES can be large enough...but backing into them....oh, oh.......

Blue Ribbon · 05-22-2008, 09:53 AM

I had the same problem, if the back was down ever so slightly. I could generally breat the syphon a couple ways. Drive it 10 feet, and slam on the breaks, and shuffle everything in every cabnet. Or go down a slight hill - neither was a good option.

The dealer changed the vent line, which involved pulling off the bottom 1/3 of the back cap, but it did no good.

I just put a 1" ball valve on vent line, and after filling, when the tank starts peeing, just cut it off. By the time I drive to site, and open the valve, it has stopped. You can't forget and leave the valve closed, because the pump will continue to pump, and the tank will go flatter and flatter. I don't know when it will split.

Ken C · 05-22-2008, 07:36 PM

I had the same issue on both our current and previous NRV coach. I used the same modification as listed by Bob Dopher which fixed the problem.

Zogman · 05-26-2008, 03:17 PM

Bob & Ken, I crawled under the back of the coach and I am not able to see where the tanks connnect. Where do I access the to make this "T" upgrade. Any help would be appreciated. Thanks

Hesaskip · 05-31-2008, 03:00 AM

The fix is a trip to the hardware and purchase an anti-siphon valve and install on the drain line. When we purchased our 99, our tank would siphon empty. The dealer installed the anti siphon valve. No more problems. It will let pressure escape as you fill the tank, will even let water out to let you know it is full, but when the siphoning starts, it shuts off.