2019 Seneca fresh water tank self siphons

Rino · 05-12-2019, 02:16 PM

I have used my Seneca a lot and have not had this problem. I filled up my fresh tank (with a pressure regulator) about 45 minutes out from our dry camping location. I stopped filling when I saw the water start to run out the over flow hose. As I was getting ready to leave I noticed it was slowly running out of all 3 hoses hanging down but seemed to be slowing. When we got to our campsite the fresh tank was empty. Some how the tank siphoned itself down to about an inch full. Luckly I found a nearby water source but was still a pain as we noticed we were empty after we were all set up. Has anyone had this happen before and is there a way to prevent it? Everything worked fine when I filled the tank back up.

Rustynuts · 05-12-2019, 02:25 PM

Very common problem.....the link below is a discussion on it and the easiest is to make an air break to stop it from siphoning.

https://www.jaycoowners.com/forums/f...ing-54340.html

Sundancer330 · 05-12-2019, 02:25 PM

Put a valve on the end overflow tubes, fill the tank when it starts to overflow close the valve, dont forget to open once you arrive to vent the tank or you won't have any water

Grumpy · 05-12-2019, 02:47 PM

I think RobbyR made a manifold air break to stop that from happening, hopefully he"ll chime in.

Rustynuts · 05-12-2019, 03:24 PM

Quote:

Originally Posted by Grumpy

I think RobbyR made a manifold air break to stop that from happening, hopefully he"ll chime in.

The link I posted above was where he showed his work and my version. Here is another link discussing the issue.

https://www.jaycoowners.com/forums/f...ank-54228.html

Robbbyr · 05-12-2019, 05:15 PM

I'm an owner who advocates for a permanent air break setup versus plugging and unplugging the overflow/vent lines. Takes the "human factor" out of the equation. One of the previously-mentioned posts shows the unfortunate results of forgetting to open the valves when using the water pump; I have also seen instances where freshwater tanks have been split open while filling when the overflows are closed. Nowhere for the pressure to escape!

I don't know what might have changed regarding the water tank locations in new Senecas, I was lucky enough to have room above my tank to install my air break manifold. My manifold also incorporates the return-to-tank line for my hot water recirculation system I installed. That line obviously isn't necessary just for the air break function.

Rino · 05-13-2019, 02:32 PM

Thanks all for the input. Nothing worse than getting all set up and realizing you are out of water!

Grumpy · 05-13-2019, 03:40 PM

Rustynuts: Sorry, I completely missed the link.. OLD AGE hits again....

Rustynuts · 05-13-2019, 05:25 PM

Quote:

Originally Posted by Grumpy

Rustynuts: Sorry, I completely missed the link.. OLD AGE hits again....

No problem, I have done the same thing myself

SloPoke · 05-13-2019, 08:26 PM

We have the same dang problem with our 2015... it has been going on for years. If you really overfill your water tank... all three drain hoses will keep draining until you suck the tank into collapse. It only takes a couple of minutes - I walk around briskly and still lose half of the tank. All they really needed is a vent that is above the level of the tank that terminates above the top of the tank... I did it last week - again!

MD3 · 05-14-2019, 06:28 PM

I did the manifold and was still getting some water loss.
I went ahead and put a valve on the overflow.

Freshwater is important enough that we installed a second tank to haul an additional 58 gallons. I don't want to lose any going down the road.

_

RVermont · 05-15-2019, 04:42 AM

If you install a valve and are concerned about forgetting about opening it you could always install a vacuum relief valve. This would allow air in but no water out. I ran the 1/2 overflow into a 3/4 pex pipel and looped it on the ceiling. This eliminated the water loss. I also installed a valve to shut this vent. I only close the valve to stop the siphoning if I forget and allow the tank to overflow when filling. Once the lines drain I can open it and no siphoning occurs.

I would like a larger freshwater tank but the gray tank is also a problem and can not even take all the fresh. With the carrying capacity of these units you would think 100 gallons of fresh and grey would be reasonable. 850lbs is well within our capacity.

Berjr · 05-15-2019, 11:40 AM

In our Greyhawk, I closed off 2 of the 3 vent hoses with caps and then ran the third one up high above the top of the water tank. This worked for me and solved the water loss issue

MD3 · 05-16-2019, 09:39 AM

I fill my water tank till it over flows. Close the valve. Open it when we get to where we are going.
I've forgot to reopen the valve and ran and few toilet flushes with zero issues but I do understand the concern of not venting the tank when using it.

We have the RB model so we have 64 Gallons Black / 90 Gallons Grey with a way to pump grey into the black if the grey gets too full. We can carry all our wastewater from the 129 Gallons (71 + 58) of fresh water that we carry.

_

Pmcmath · 05-16-2019, 08:24 PM

Maybe weird or one time thing but today I was filling ours....normal fill and run off and when it started overflowing I turned my pump on and it immediately stopped....I figured maybe it put some air possibly in the system...not sure.

RVermont · 05-17-2019, 05:37 AM

That is exactly what you did. When you turned on the pump the suction of the pump overcame the siphon effect in the vent line and pulled air into the vent line. Thus breaking the siphon.

Robbbyr · 05-17-2019, 05:59 AM

Quote:

Originally Posted by RVermont

That is exactly what you did. When you turned on the pump the suction of the pump overcame the siphon effect in the vent line and pulled air into the vent line. Thus breaking the siphon.

I also found that if you got it to stop while parked, you were fine. But since the tank was still very full, my first driving (especially cornering) caused it to slosh enough to start it again. Or maybe the tank was flexing enough to "squeeze" itself and push water out the vents. Regardless, I could see my "trail" following me in the mirror going around the corners!

I like being able to fill from a pressurized source using the valves, but sometimes I wish it still had the plain old gravity fill and vent setup.

Nunzo · 05-22-2019, 12:13 PM

I had the same issue and found that fill rates make a difference. If I hook up water from hose at lower pressures, a air gap does not form. If I crank the water pressure up when filling the fresh water tank, an air pocket fora which drains the tank.

Dancingqueen · 05-22-2019, 01:02 PM

My Seneca is a 2008. I was told by dealer to shut off water at hose bib, reschedule controls to City Fill, turn on water and fill. Then when full, turn off spigot again, set controls to Normal and I’m good to go. Very simple and works well unless I forget to shut water in between then out comes water thru drain hoses.

pconroy · 05-22-2019, 09:16 PM

Quote:

Originally Posted by RVermont

That is exactly what you did. When you turned on the pump the suction of the pump overcame the siphon effect in the vent line and pulled air into the vent line. Thus breaking the siphon.

exactly what I do.

fill until I hear the overflow, then turn off the hose and immediately pump on and outside shower on.

flow a little water thru outside shower and the tank stays full

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