Siphon Action Draining Water Tank - Problem Solved!

[Cate&Rob]

Back in February, we debated the latest ideas on how to stop the siphon action that can drain a substantial amount of water from a full water tank. About post #62 (of 96!) I suggested that a second parallel overflow pipe would break the siphon vacuum in the first and stop the draining. There were several ideas about taking this second vent line higher and/or to remote locations . . . but, this is not necessary. The entire discussion is here https://gdrvowners.com/forum/operati...esh-water-tank for anyone who wants to read through it.

At a recent meeting between the moderators of this forum and Grand Design, I proposed this idea as first described back in February and as detailed in the attached pdf. Grand Design proceeded to investigate this concept and have advised that their testing has proven that this idea works to stop the siphon action and they will begin installing the double overflow pipe across all production lines.

Updating an existing system to this design should be relatively easy and inexpensive. All that is required is a Pex tee, a couple of short lengths of Pex pipe and a few Pex clamps.

This fix will not stop "slosh pumping" while towing, but if this starts a siphon action, the double overflow will stop this with minimal loss of water. This fix will not require a shut off valve that needs to be remembered when filling or using water from the tank.

Rob

Breaking Water Tank Overflow Siphon.pdf

[trkester]

Back in February, we debated the latest ideas on how to stop the siphon action that can drain a substantial amount of water from a full water tank. ...

At a recent meeting between the moderators of this forum and Grand Design, I proposed this idea as first described back in February and as detailed in the attached pdf. Grand Design proceeded to investigate this concept and have advised that their testing has proven that this idea works to stop the siphon action and they will begin installing the double overflow pipe across all production lines.

....

Updating an existing system to this design should be relatively easy and inexpensive. All that is required is a Pex tee, a couple of short lengths of Pex pipe and a few Pex clamps.

...

Rob

[ATTACH]n52087[/ATTACH]

Super. Congrats. Great innovation and design.

[TucsonJim]

Great job Rob. This vent is henceforth called the "Rob Vent".

As soon as my hand heals up, I'll implement the change and let you know the outcome. My rig has been especially prone to this phenomenon.

Jim

[Canyonlight]

Awesome, Rob ! With the significant number of folks posting water loss as an aggravation (or worse) over the years, this is good news. Well done to you and the other Mods./other folks/GDRV team involved !

Dan

[ThePowells]

Rob, 3/4 inch Pex? I am 95% sure that my vent tube is 1/2.

[TucsonJim]

Rob, 3/4 inch Pex? I am 95% sure that my vent tube is 1/2.

On my 2017 Reflection, it's 3/4".

Jim

[TedS]

My 2021 Reflection has 3/4 inch. My previous Open Range had 1/2 inch.

[Cate&Rob]

Rob, 3/4 inch Pex? I am 95% sure that my vent tube is 1/2.

The last picture in the attachment to post #1 was sent to me by Grand Design. It is of the first Solitude built with the double overflow lines. They appear to be 3/4" if you compare to the 1/2" fill/supply line in the lower left of the picture. The overflow line on my Reflection is 3/4". Of course . . . some could be built with 1/2" overflow .

Rob

[JCR GD]

Rob, do you mind if I send the PDF to my brother who is a member of the Open Range forum? They have the same problem.

[Cate&Rob]

Rob, do you mind if I send the PDF to my brother who is a member of the Open Range forum? They have the same problem.

Hi Jim,

Since I have posted this information on an open forum, it is (technically) available to anyone. If you want to provide this to another forum, I would prefer that you used the attached version titled "Solving Water Tank Vent Siphon". This still describes the idea and identifies more clearly where it came from but removes the direct confirmation that Grand Design is going to implement this.

Rob

Solving Water Tank Vent Siphon .pdf

[JCR GD]

Hi Jim,

Since I have posted this information on an open forum, it is (technically) available to anyone. If you want to provide this to another forum, I would prefer that you used the attached version titled "Solving Water Tank Vent Siphon". This still describes the idea and identifies more clearly where it came from but removes the direct confirmation that Grand Design is going to implement this.

Rob

[ATTACH]n52215[/ATTACH]

Ok thanks! He will (and they) will appreciate it!

[OffToHavasu]

Rob,

I'm glad you FINALLY got you constant drip problem resolved. There are other alternatives, but I'm glad you went to GD to get it fixed. )

So since I'm still under warranty for 30 more days...

[JCR GD]

Hey Rob,

My brother posted the "solving" PDF and

First reply:
ingenious idea. Just goes to show GD RV'ers are just a little smarter!

Thanks again

[grampscamper]

This is my fix. I didn’t want to remove the underbelly covering. I installed a T with a shutoff that I leave open when I fill my tank. Once the tank is full I close the valve for travel. From the T I ran pex forward to the docking area. I haven’t had an opportunity to road test it but I know it will work based on information I discovered on another thread.
Rob, great to hear Grand Design has taken steps to resolve this issue. I was loosing 1/3 of my tank because of siphoning. Sorry about the rotated pictures.

[J & J Bumblebee]

That's pretty cool that they went with your idea. Congratulations!


John