2018 Seneca crushed water tank

[Harbour35]

I removed some of the panels that close off the tanks and the space across the rails.
When I got to the panel that exposed the fresh water tank I was shocked at the condition of the tank. It appears to that the tank is distorted and crushed.
The vehicle has only been used for 5 days (returning home to Alabama from purchase in Quartzsite) I am the second owner but it only had 5200 miles at purchase.
Not sure of the cause or the solution to the problem. Any input/suggestions are welcome.
Pictures attached.

[hoppers4]

If your air inlet vents are plugged (looks like at least one is pinched closed) the water pump is strong enough to collapse the tank. You could possibly expand it out by refilling it with water to the point of slightly pressurizing it.

[Sundancer330]

I would agree it looks like a vent problem, or you have some big rats that have been dancing on it.

[Robbbyr]

I wonder if someone installed valves or plugged the vents to address a siphoning problem? Would love to follow those vent/overflow lines to see how they terminate.

[Grumpy]

Originally Posted by Sundancer330

I would agree it looks like a vent problem

Do those hoses have valves on the end? If so the pump was used with them closed.

[Harbour35]

Thanks for the response. I thought about a vent issue. I do not understand the 3 fittings if they are all vents.
I will have to look in more detail tomorrow.

[Sundancer330]

Originally Posted by Harbour35

Thanks for the response. I thought about a vent issue. I do not understand the 3 fittings if they are all vents.
I will have to look in more detail tomorrow.

Follow those three hoses and see if they are open on the ends. As others said some owners put shut off valves on the hose ends so when they travel with full water tanks they close the valves to keep the water in. If the valves are closed and you start pumping water with no vent this is what will happen. The hose on the left in the picture looks kinked or collapsed it may need to be replaced.

[Robbbyr]

Originally Posted by Harbour35

Thanks for the response. I thought about a vent issue. I do not understand the 3 fittings if they are all vents.
I will have to look in more detail tomorrow.

I was at the factory service center last year and I spoke to them about a siphoning issue I had. They explained there are 3 vents since our Senecas, and many other Jayco models, can direct full city water pressure via the panel valves to the water tank when filling. Jayco wanted to make sure the tank does not overpressurize and rupture if the tank completely fills and the water supply is not stopped immediately. Hence 3 overflows. Other RVs with only a "gravity fill" for the freshwater tank don't generally have the same potential to overpressurize the tank.

But as stated in the earlier posts these same overflow tubes function as vents to allow air to enter the tank as you use water. If the tubes are blocked, when the pump is operated the tank will go negative (below atmospheric pressure) and collapse.

To that end, Jayco told me it is better to install an air break to stop siphoning versus blocking the overflow/vent lines. Less chance of trouble if the vents are not opened before filling or use of the tank. I built and installed my own air break and it has eliminated my siphoning issue.

[RVermont]

I had a similar issue with my tank. First the tank is not secured side to side and the only thing stopping it from moving forward is a small block of styrofoam. So the tank shifted toward the vent hoses and the hoses were the only thing holding the tank in place. This shifting crushed and pinched the vent lines they look just like these but I had only used my tank once so it did not collapse. I pulled the tank out and placed wood supports under it as other have done. On top of plastic pan I added 1” insulation and then replaced the vent lines with valves but will probably do a vacuum break like robbbyr shows. Finally I used a shower bar to secure the tank from moving. I also left the cover off so I can see the tank level and monitor it for any issues.



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[RVermont]

Robbbyr. Is the red line the hot water return line for your hot water preheat system? I think you mentioned that in a different post.


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[Robbbyr]

Originally Posted by RVermont

Robbbyr. Is the red line the hot water return line for your hot water preheat system? I think you mentioned that in a different post.

Yes it is. My manifold is fabricated in a "U" shape, the hot water return connection is on the same 'leg" of the U as the connections to the tank. It doesn't show very well in the photo, but that side is lower than the vent side. The overflow tubes are connected to the "high side" as it is installed. So the hot water being returned flows into the manifold and then drains into the tank. If the tank is full, the returned water just runs out the overflow tubes.

When I fill the water tank as it reaches the top it first fills the new manifold and then spills out the vent lines. And when driving the manifold provides an air gap and keeps it from siphoning when the tank is full. I arrive at my next stop with the same amount of water I left with!

More photos of the recirculation plumbing here:https://www.jaycoowners.com/forums/m...lbums1497.html

[RVermont]

Perfect. Thanks. I will probably work on this once the snow goes down a little.


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[Robbbyr]

Originally Posted by RVermont

Perfect. Thanks. I will probably work on this once the snow goes down a little.

Happy to help any way I can!

[Harbour35]

Thanks for the reply and photo. I plan to do the same thing to resolve my problem after I figure out how to re-expand the tank. Thinking small ceramic heater and regulated air pressure or fill with warm water and apply air.

[norty1]

They are not real thick and do flex. That picture looks to me as others have advised that it has a suction on it due to a vent clogged. I would support those crimped lines somehow and make sure the tank is properly vented. As long as it is not leaking, I would not be to concerned when the vents are checked out.

When full the tank will likely look normal.

[Robbbyr]

Originally Posted by Harbour35

Thanks for the reply and photo. I plan to do the same thing to resolve my problem after I figure out how to re-expand the tank. Thinking small ceramic heater and regulated air pressure or fill with warm water and apply air.

Not sure what your outdoor temps are like, can you get into a heated building? I would think as warm as practical would be best. After rig is completely warm I would likely try a combination approach, extra heat from a space heater (but not aimed right at it) warming the tank area followed by filling with warm water. Gentle air pressure when full to expand it back out. Then perhaps more water to fill the opened up space and "hold" it in place until the tank completely cools back to ambient. Hopefully tank still tight afterwards and retains it shape.

If I ever had to remove and replace a tank on my 2014 TS the freshwater tank would be by far the easiest. The fill/drain connection on the bottom, the 3 vent/overflows on top, and the monitoring wires are the only connections. And then it is just sitting in there, ready to slide out. The only thing I can't say for certain is whether it will come through the door opening. A tape measure would answer that. Jayco probably installed the tanks before the steel side curtains were placed. The compartment doors then attach to those curtains.

Very interested in how this progresses for you.

[RVermont]

I would agree to the approach rob states. I would pull the tank out. It took me five minutes to remove and 30 minute to replace due to new vent lines, valves and fill/ drain line. The tank slides right out. (Measure yours to be sure) Doing the expansion out side of the rig allows you to inspect the rippled area to be sure there is no crack. While these tanks measure to 70+ gallons the large flat top sags quite significantly and reduces the actual volume. By up to 5-10 gallons or 10% The top dipped around 2 inches. By adding the supports under the tank I actually think i further reduced the volume as the bottom is now flat instead of dropping between the rails like it was before.


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[McGintys924]

RVermont has a thread where he took his tank out and put boards underneath. This is definitely on my list, but would include insulation between boards under the plywood, and a 110v tank heating pad (might as well when it’s out). There is a lot of loss that occurs from those drain valves so I need to come up with Robs solution to that when the tank is out. I think you have good suggestions on how to reform the tank (which might be easier out of the RV since it would fit inside the home) but maybe some ideas for modifications before you put it back.

[Harbour35]

The tank had shifted to the right (Pass) side at some point. It must have happened with a partially filled tank. I think water slosh shifted the tank and caused it to drop below the bracket mounted to the underside of the floor.
The tank was at a angle against the closure panel causing all ( 3) three of the vent hoses to be crimped closed.
The tank gauge had always shown full from the time I accepted delivery of it.
My first 5 days of the return trip home (Quartzsite AZ to Orange Beach AL) were at campgrounds with water hookup. The last 3 days were operating from the tank so that is likely when the bulk of the implosion took place.
I am going to be re-installing the inflated tank tomorrow and modifying the retainer bracket to prevent the tank from moving again. Light air pressure expanded the tank to almost the original shape and I believe a full tank will further expand.
I will also be installing a air break to prevent siphoning as part of the re-installation. Since the tank is out I am also installing a 12v. tank heater pad just in case I ever need it.

[RVermont]

I would be willing to bet that almost every water tank has moved but since they are behind the “wall” no one knows. The only thing holding it at all we’re the vent and drain lines.


I installed 1inch styrofoam under mine and added supports under the shell. I think the tank heater is a great idea. I used a shower rod with padding on it to keep the tank in place. Wanted to be sure that the holding device did not wear a hole in the tank

Glad to hear that it has popped back out.


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