Siphon Action Draining Water Tank - Problem Solved!

[Yoda]

Remember that the overflow/vent line has to allow air flow in both directions. Air has to exit as the tank is filled and enter as water is used from the tank. In your plan, you would still have to remember to open the valve when filling the tank. Forgetting the valve when pressure filling could potentially cause the most damage, taking the tank to fill pressure of something like 40 psi.

Rob

Very correct Rob. This is just to prevent tank collapse (suction) if thy forget to open the vent during use. I am thinking a simple free floating ball check valve, or air/vac valve like I have on my system might work if they will work in a sideways configuration. Unfortunately not much information on that out there.
Guest Jim do you have a link to the valve you used on the end there - looks interesting.

Rob your solution is an excellent fix and I think GD is making a wise choice implementing it. Will be interesting to see how it performs, especially in sloshing situations.

All I am offering is this as possible measure to prevent tank collapse if folks forget to open in use. Nothing I can do to prevent tank expansion during filling. The air/vac valve I have on my system in the Nautilus bay does allow air to exit, but probably not enough at wide open fill. It might work in the horizontal T situation too as the ball is free floating.. And once water reaches the ball and it closes, nothing gets out. Having that pipe end open in my nautilus bay is probably the best thing for me to change in my set up.

[Cate&Rob]

Some excellent perspectives in this latest discussion. I cannot speak for Grand Design, but I can provide a little "history". The tank overflow/vent pipe was part of early production which was Solitude, Momentum and Reflection. These models do not have gravity tank fill provisions. The water control panels are in closed compartments, so the panel "vent" connection could not be used since it would flow water when the tank was overfilled.

Imagine and Transcend models with gravity fill connections came into production later, but the water tank vent pipe design continued from the earlier models. I can discuss with Grand Design, whether there is a way to eliminate the overflow pipe with sufficient venting through the gravity fill provisions on Imagine and Transcend. The venting would still have to comprehend the volume of water/air during pressure filling.

Rob

[flyfshrockies]

Cate&Rob Rob, thanks for the offer to discuss this item with GD regarding the Imagine and Transcend lines. It would help future owners greatly not to have this frustration. I do understand the other side of this with regards to lines that have only power fill option, however it would seem that a small screened vent located on the same side as the fill valve/Nautilus system would work as well as the current vent system on the other lines. When it spits water the owner could turn off the power fill and be done with it. In my experience with several t.t. of several brands over many years the set-up with the vent plumbed to the screened area colocated with the gravity fill worked well and never created a problem with the tank or sloshing while traveling. Tradition can sometimes be the enemy of common sense solutions and progress. We restored an antique aircraft that was covered with Irish linen and replaced that with a modern, at that time, fiberglass, the material had 5 times the service life... progress. My guess is that it would be easier and less costly than the current system for GD to revert to the old style vent on the Imagine and Transcend lines. The vent location and screen are already part of the current set-up. Again, thanks

Dave

[rpkramer]

Did you take pics of the install , I have a 29RS as well. Have you traveled yet with the new set up to see that it does work?

I too have installed a valve on the overflow and also have forgotten to open it.

Brian

Brian, I did not take pictures. This was not an easy job. Just getting access but then figuring out how to get the pex crimps off without cutting into electrical wires and 4" furnace supply hose. I have not tried it out yet.

[TucsonJim]

Update: Paul & Deb just bought a new Imagine and it came with the dual vent tube. Kudos to Cate&Rob for helping GDRV solve this nagging problem.

Jim

[Paul & Deb]

Update: Paul & Deb just bought a new Imagine and it came with the dual vent tube. Kudos to Cate&Rob for helping GDRV solve this nagging problem.

Jim

True. I went to add my sharkbite stop**** to the new trailer and found two overflow tubes. I said WHAT? Did GD make a booboo? Nope, they incorporated Rob's design. I haven't tested it yet but, in my book, if Rob sys it will work then it will work! Thanks Rob!!

EDIT: Haha, I just noticed this software censored my post! Haha

[Canyonlight]

Update: Paul & Deb just bought a new Imagine and it came with the dual vent tube. Kudos to Cate&Rob for helping GDRV solve this nagging problem.

Jim

This is great to see production. Another poster elsewhere was asking about this new design as well.

Just to, this is another item in a long line of suggestions to improve the product and ownership experience over nearly a decade now, where GDRV has encouraged and listened to owner and other stakeholder feedback.

Those of us who have been around for a long time with GDRV can attest to all the changes and improvements in GDRVs from early build units. Years ago, we "listed" the number of enhancements suggested and in rather quickly made in production. I do not recall the exact number any more but it was easily more than 3 dozen........and this was a few years ago.

Kudos again to Rob Cate&Rob on this key item and to GDRV for a listening and having a caring partnership with us owners !

Dan

[Tbuckley82]

I have an early 2022 model Imagine 2600BH, delivered in late June, 2021. I am suffering from this issue of water loss and stumbled into this forum. We bought the unit from Bretz RV in Missoula, MT and they have been unhelpful in solving this issue. Since the design change has been implemented by Grand Design, are there any certified technicians that would be able to fix this issue? I am personally not likely able to install the fix myself. Wondering what experiences people have had now in 2022.

[TucsonJim]

I'm can't wait any more. I need to drop the underbelly and apply Rob's fix. A couple of weeks ago, I filled my fresh tank and let it go too far. It started to spill out of the overflow. I could not get it to break the siphon no matter what I tried. I pressed the input valve to let air in, and there was no stopping it. I ran a few gallons of water out of one of the faucets, and the overflow kept spilling out. I opened the drain valve which did nothing more than start draining the water out of both the overflow and the drain valve at the same time. Water was still coming out of the overflow tube when I was at only 1/3 of a tank. The only way I could get the flow to stop was to use my compressor to pump air into the overflow! This has to be terrible on the fresh water tank. Now, I just need some cool weather here in Tucson before tackling this project.

Jim

[StephenO]

I'm can't wait any more. I need to drop the underbelly and apply Rob's fix. A couple of weeks ago, I filled my fresh tank and let it go too far. It started to spill out of the overflow. I could not get it to break the siphon no matter what I tried. I pressed the input valve to let air in, and there was no stopping it. I ran a few gallons of water out of one of the faucets, and the overflow kept spilling out. I opened the drain valve which did nothing more than start draining the water out of both the overflow and the drain valve at the same time. Water was still coming out of the overflow tube when I was at only 1/3 of a tank. The only way I could get the flow to stop was to use my compressor to pump air into the overflow! This has to be terrible on the fresh water tank. Now, I just need some cool weather here in Tucson before tackling this project.

Jim

I've been debating about installing this fix too, looks straight forward enough, but the devil's in the details. I look forward to reading your write-up on the install I had a similar situation as yourself where I couldn't break the siphon after filling the fresh water tank and then parked the trailer beside a curb. The road was slanted towards the passenger side and that started the flow....only way I could stop it was by driving up on blocks to get the water line to sit below the overflow. Frustrating for sure!

[Jlawles2]

Once the flow starts, put your finger over the vent and stop the flow. Then open the drain slightly and allow some water to escape, occasionally slowly remove your finger from the vent and see if it has stopped.

[Cate&Rob]

TucsonJim

To stop the siphon, I would try inserting a drinking straw up the overflow pipe. This should provide a return path for air, similar to how the second overflow pipe provides return air to break the siphon. I have never tried this . . . but, it would be interesting to see if this works. Maybe hold your thumb over the end of the straw as it is inserted to maintain the column of air inside the straw?

Rob

[TucsonJim]

TucsonJim

To stop the siphon, I would try inserting a drinking straw up the overflow pipe. This should provide a return path for air, similar to how the second overflow pipe provides return air to break the siphon. I have never tried this . . . but, it would be interesting to see if this works. Maybe hold your thumb over the end of the straw as it is inserted to maintain the column of air inside the straw?

Rob

I'll certainly give that a try Rob. I like your idea too Joseph.

Jim

[Yoda]

I'm can't wait any more. I need to drop the underbelly and apply Rob's fix. A couple of weeks ago, I filled my fresh tank and let it go too far. It started to spill out of the overflow. I could not get it to break the siphon no matter what I tried. I pressed the input valve to let air in, and there was no stopping it. I ran a few gallons of water out of one of the faucets, and the overflow kept spilling out. I opened the drain valve which did nothing more than start draining the water out of both the overflow and the drain valve at the same time. Water was still coming out of the overflow tube when I was at only 1/3 of a tank. The only way I could get the flow to stop was to use my compressor to pump air into the overflow! This has to be terrible on the fresh water tank. Now, I just need some cool weather here in Tucson before tackling this project.

Jim

Jim just throw a sharkbite valve on it and be done. Fill you tank (valve open), let it overflow a bit after turning the fill water off and close the valve. Drive to your destination and then open it for use. Easy fix until you drop the belly. You can safely use about 10 gallons out of the tank before needing to open the valve to vent it.
Keith

[TucsonJim]

Jim just throw a sharkbite valve on it and be done. Fill you tank (valve open), let it overflow a bit after turning the fill water off and close the valve. Drive to your destination and then open it for use. Easy fix until you drop the belly. You can safely use about 10 gallons out of the tank before needing to open the valve to vent it.
Keith

Keith,

I have a valve installed and it made no difference at all. I could stop the flow with the valve, but even after more than half the tank was gone, the flow would start right back up as soon as I opened the valve. I believe that no air was getting into the system and the flimsy water tank was collapsing. It's never been this bad before.

Jim