More water issues

[Louis s]

Our first trip in our 2021 Momentum 28G was a disaster! When we got to our boondocking site in South Fork Colorado our fresh water tanks were bone dry! Its a 4 hr drive for us from Albuquerque NM. Luckily we were able to refill our tanks in town and continue with our vacation. Its a siphon issue and we finally got it fixed. GD paid the RV dealership to fix the problem. I suggest you contact Kent Roberts at GD main office. He is the warranty manager there. I've attached the sketch he sent me and here is his email address - [email protected]

I also added the shark bite shut off valves. If you do this make sure they are open when filling the tanks and once water starts to flow out of overflow tube close them. This has solved the water loss completely and on our last trip we had all of our water when we got to our campsite!

[IBEW Sparky]

It's actually siphoning and not just the sloshing around (the overflow tubes go up inside the tanks, come out the top, and then back down to where you see them). GD has supposedly implemented a solution to this, but I think it has been very recently. Some folks put petcocks on the overflow tubes and turn them off before travel (you have to remember to open them when setting up, though). I have dealt with the problem on both of our rigs this way: when the tank is filled and water starts coming out the overflow tube, I quickly turn off the water, switch the Nautilus system to "Dry Camping," and turn on the water pump. I then run water through the outside shower hose until the overflow tube tops flowing. This indicates that there is no longer water in the overflow tube and it will not siphon. We've never lost water in transit this way. I don't know how or if this will work on your two-tank system.

Rob

On my 337RLS the overflow pipe does not come out the top of the tank it comes out the side of the tank! I recently decided to make some modifications to my fresh watertank drain location and unscrewed the 1½" gate valve on the bottom of the tank. Looking up into the tank I could easily see the molded bung hole port on the sidewall of the tank, it's located as close as they could possibly fit it to the topside of the tank. The tank is only 8" tall (to fit inside frame cavity) but the bottom of the drain port is almost 2" down from the top oh the tank! That means right of the bat you are losing 25% of your water even just parked on level ground! I sure hope that 25% is above and beyond the rated capacity of the tank.





So after seeing this I decided to add a "T" and ball valve and run the overflow vent to the front propane compartment as others have suggested. This didn't work out since that line remained full of water down from the tank location to the front of the RV and back up to the height of the tank essentially creating a long trap of water. I ended up repiping it down to a bracket I installed and adding the ball valve on the overflow vent pipe. I also relocated the tanks dump valve to this bracket because I was getting tired of having to crawl underneath the RV reaching behind the wheel to drain the fresh water tank.

[merrittbtgd]

Same problem with 22SBE (sold it and have Rockwood). The overflow is located too low. I hooked a pex tube to overflow under coach and ran it to the front then turned back up for 8" or so. Loses some water but helps the problem. Put as push-on supply valve to the overflow pipe (1/2" pex) and hook the drain to front to it. Shut the valve. Open to drain all water for winter storage.
My old Holiday Rambler would belch water when tank was full. No water lost in transit. Bon

[Reddog303]

Just returned from a 6 night boon docking adventure and have another water issue. Installed the shark bites on my vent lines ,filled tank until water started to flow from the first tank vent line checked the gauge ,full so shut off water .Went to leave next morning checked water ,now 2/3 of a tank on gauge ,well 6 days should not be an issue after all we have a 100g.First 4 days all good ,get down to 1/3 tank now the pump will not pressurize the water lines. It runs continuously and supplies intermittent water but not pressurized or steady stream. Ok maybe the gauge is out and we have used more than we thought although I new the tank was full before we left. Go to dump the water tanks before we leave thinking not much there,wow yes there was at least 15 gallons left between the 2 tanks as both dumps run a steady stream .Ok now is there a pick up problem with the pump ?Has anyone else experienced this??.A big shout out to Louis S and IBEW Sparky that was great info. When I got to our campsite opened both shark bites and a splash of water came out so they were good.RD

[huntindog]

Just returned from a 6 night boon docking adventure and have another water issue. Installed the shark bites on my vent lines ,filled tank until water started to flow from the first tank vent line checked the gauge ,full so shut off water .Went to leave next morning checked water ,now 2/3 of a tank on gauge ,well 6 days should not be an issue after all we have a 100g.First 4 days all good ,get down to 1/3 tank now the pump will not pressurize the water lines. It runs continuously and supplies intermittent water but not pressurized or steady stream. Ok maybe the gauge is out and we have used more than we thought although I new the tank was full before we left. Go to dump the water tanks before we leave thinking not much there,wow yes there was at least 15 gallons left between the 2 tanks as both dumps run a steady stream .Ok now is there a pick up problem with the pump ?Has anyone else experienced this??.A big shout out to Louis S and IBEW Sparky that was great info. When I got to our campsite opened both shark bites and a splash of water came out so they were good.RD

Maybe a leak in the suction line?

[DougW9876]

Reddog303:


I have had a lot of RV’s over the years and a very common problem is that the water pickup is NOT in the bottom of the tank, it is often on the side of the tank near the bottom so when the water level gets down to around 3 inches of water in the tank the pump will start to suck air. It could be you have this problem, it should not be difficult for you the check and see if that is the problem.

It would be so nice if the manufacturers would put a 2 gallon sump on the water tank and put the pickup for the pump in the bottom of that sump. We could then use all of our water without problems.

[Reddog303]

Thanks Doug that would explain a lot ,we did have a slight port list so that would even exacerbate the problem. I tried lift the nose and dropping it to see if the pump would pick up better but no joy. This would be a lot easier if GD had some schematics I could follow but trial and error and this forum seems to be working through these issues. Huntindog checked the pump when I got home ,filled both tanks worked perfect right up to pressure. So trudge merrily along thanks again for the info

[Dakota]

Just heard back from my dealer who recommended NOT filling the tank full.HUH ,so why have a tank you can't fill ,but it gets better ,when I told them I had 2 tanks they said oh might have to put a check valve in ,,,

I think I heard or read that too. So how do I know it’s almost full before it comes out the overflow tube?

[IBEW Sparky]

I think I heard or read that too. So how do I know it’s almost full before it comes out the overflow tube?

You won't know.... untill it comes out the overflow of the tank. I think any dealership service rep that tells you you shouldn't fill the tanks full is just handing you a line of BS. Add a valve to the overflow pipe and when water comes out shut off the water supply and immediately close the valve. Just remember to open the valve when you're rig is all levelled up and ready for use.

[Scott'n'Wendy]

The pic posted up by Louis is how GD are doing the overflows on the production line now...or so I was told. The 'T' will prevent the siphon action from occuring.