Siphon Action Draining Water Tank - Problem Solved!

[bh11111]

Hello, has the .pdf been removed from the first thread? I try to download it and just get a small text file... I'm so glad that there is a fix for this. It's kind of a bummer to show up at your dry campsite with only a small amount of fresh water left in the tank... Thanks!

[Country Campers]

Hello, has the .pdf been removed from the first thread? I try to download it and just get a small text file... I'm so glad that there is a fix for this. It's kind of a bummer to show up at your dry campsite with only a small amount of fresh water left in the tank... Thanks!

The .pdf file still works for me. You may have to disable pop ups or have Adobe installed on your device. When I click the file it asks me if I want to view or download.

Brian

[Cate&Rob]

bh11111

Welcome to our owners technical forum. When you have a chance, have a look at our welcome post. https://gdrvowners.com/forum/main-fo...to-new-members . This will help you set up your signature and navigate the forum.

I added a second copy of the same file to the original post. I can't see any difference in the two files and can open either one. Let me know if you still have a problem.

Rob

[howson]

Hello, has the .pdf been removed from the first thread? I try to download it and just get a small text file... I'm so glad that there is a fix for this. It's kind of a bummer to show up at your dry campsite with only a small amount of fresh water left in the tank... Thanks!

If you tried to download the PDF before signing up (and logging in to the forum) that would explain why the download didn't work. Now that you've got an account it *should* work.

[bh11111]

Thanks for all your help with the Pdf. I was able to download it no problem this morning. I guess it had to do with me not being registered when I initially tried to download it. I'm looking forward to getting the siphoning problem solved now.

[TedS]

Resurrecting this old thread with yet another idea I read. Where you have the typical vent connection at the top of the tank side and run down through the coroplast. Run a loop of hose around the tank, the article called it a racetrack, and back down through the original hole in the coroplast. Turn the existing fitting above horizontal. The hose can have a bit of an uphill rise before turning down to exit. Makes it difficult for water to slosh out and will not siphon. Requires no cap or valve to forget when filling the tank.
FWIW.

[Julann]

I too have had the siphoning nightmare, last week as a matter of fact. How would I get this done since it is beyond my skill set? Is this something dealer service can do? Since Grand Design is adopting, do you suppose they would provide the dealer service departments the documentation?

[Yoda]

I too have had the siphoning nightmare, last week as a matter of fact. How would I get this done since it is beyond my skill set? Is this something dealer service can do? Since Grand Design is adopting, do you suppose they would provide the dealer service departments the documentation?

Julie
For you 220RK you could try my solution. https://gdrvowners.com/forum/operati...hile-traveling

And welcome to the forum.

[Cate&Rob]

Julann
Hi Julie,

I don't know how Grand Design will roll this out to their dealers. I expect that trailers plumbed like this will just start showing up. Modifying an earlier build would be relatively simple. The hardest part would be dropping the side of the coroplast which is probably sealed around the water tank drain. The new parts being a Pex Tee and a few clamps would not amount to more than a few dollars in "available anywhere" parts. With the backlog at dealer service facilities, this might be worth hiring a mobile tech. With the info in the attachment to post #1 of this thread, this should be relatively easy for them to accomplish.

Rob

[Julann]

Julann
Hi Julie,

I don't know how Grand Design will roll this out to their dealers. I expect that trailers plumbed like this will just start showing up. Modifying an earlier build would be relatively simple. The hardest part would be dropping the side of the coroplast which is probably sealed around the water tank drain. The new parts being a Pex Tee and a few clamps would not amount to more than a few dollars in "available anywhere" parts. With the backlog at dealer service facilities, this might be worth hiring a mobile tech. With the info in the attachment to post #1 of this thread, this should be relatively easy for them to accomplish.

Rob

Thanks Rob. Kudos on the fix by the way!
I suspect since I am quite "geographically dislocated" mobile techs will be few and far between. My dealer is about 50 miles away. Closest real tech is probably more like 3 times that. I scheduled the rig in for the battery issue before we figured it out. They were only booking out a week so that wasn't too bad. I may look into it at the end of the season before it goes into storage so it won't matter. Sadly, it is coming too fast.

So this fix would eliminate the need for the shutoff valve during travel? How much water loss do you anticipate there would be from sloshing?

[TedS]

From other reported water loss, you could still lose up to a third of the full tank from sloshing.
Yoda's solution would be best. No sloshing loss with high vent.

[Cate&Rob]

So this fix would eliminate the need for the shutoff valve during travel? How much water loss do you anticipate there would be from sloshing?

Hi Julie,

As far as I know, no one has actually tested how much water can be"pumped" out the half inch diameter vent hose connection by slosh waves in the tank. This probably has a lot to do with the roads being travelled and the number of starts and stops along the way. What has been proven is that this slosh wave can start a siphon action in a single vent tube that will continue to drain water long after the slosh wave has subsided, by sucking in the walls of the tank. The double vent line has been proven (by Grand Design testing) to break the siphon action.

There are certainly more complex venting strategies possible and some simply put a valve on the vent line. If you go with a valve, you must alway remember to open the valve when filling or using water from the tank. Serious tank damage can occur if this valve is left closed.

Rob

[Guest]

I plan on using the shut off valve along with a vent line in case I forget to open the overflow valve.

Getting closer to being able to do some of these tasks.

Jim

[TedS]

The water needs air on top of it to slosh. There can be no siphon with air on top. The loss is initial drain to the tank fitting level, then slosh. If the tank sides draw in raising the water level to the tank vent port, then it is just draining water. Same as if the tank is tilted.

[Julann]

Hi Julie,

As far as I know, no one has actually tested how much water can be"pumped" out the half inch diameter vent hose connection by slosh waves in the tank. This probably has a lot to do with the roads being travelled and the number of starts and stops along the way. What has been proven is that this slosh wave can start a siphon action in a single vent tube that will continue to drain water long after the slosh wave has subsided, by sucking in the walls of the tank. The double vent line has been proven (by Grand Design testing) to break the siphon action.

There are certainly more complex venting strategies possible and some simply put a valve on the vent line. If you go with a valve, you must alway remember to open the valve when filling or using water from the tank. Serious tank damage can occur if this valve is left closed.

Rob

I have warnings posted by pump switches and city water intake and it is on my setup list to remind me to open the overflow valve. So far so good. I may start taping the switches to add a level of safety in case I get interrupted like you always seem to during setup. My concern is how much if any damage is occurring to the tank even when I am doing it right? On my way home from camp outs I don't bother to close the valve since I will want to start with fresh water for the next trip anyway. I always have water left in the tank when I leave the campsite, but I rarely have much of anything left when I arrive home. If the overflow is at the top of the tank, and the level is at 1/3 or less, how is it possible for that to occur unless the tank walls are sucking in. Since it has been mentioned many times of how fragile the tank is, how much can it take before catastrophic failure happens? Since I am well past warranty, I can only assume this will be on my dime even though it was, unfortunate for us, a poor design. I assume water draining from coroplast is going to be the indicator of armageddon?