Solution to water loss while traveling

**Grandesigner** · 05-06-2021, 05:36 PM

Edited my recent posts...

**TerryH** · 05-06-2021, 07:05 PM

I've seen a lot of people post about losing water including us. Never seen anyone post about the siphoning effect collapsing the tank as it states in the first slide. Anyone ever heard of a collapsed tank from this?

**sgrol60** · 05-06-2021, 07:41 PM

Collapsed tank comes from someone putting a shut off valve on overflow pipe. Then forgetting to open when water is drawn out creating a vacuum in the tank.

**TerryH** · 05-06-2021, 07:54 PM

Originally Posted by sgrol60

Collapsed tank comes from someone putting a shut off valve on overflow pipe. Then forgetting to open when water is drawn out creating a vacuum in the tank.

If you check what I posted above from the Grand Design "fix", it says that the siphon effect could collapse the tank. Doesn't seem likely to me but since GD has it in their paperwork I thought I'd ask if anyone had ever heard of that happening.

**gbkims** · 05-06-2021, 09:50 PM

Saw one reference about a tank collapse - https://www.mygrandrv.com/forum/show...ll=1#post78114

**RickLight** · 05-07-2021, 10:13 PM

Yeah, it certainly means dropping the coroplast! I'm building quite a list of tasks for when it comes off.

The distance from tank outlet to floor may vary by rig, but it won't be large. Even if it's level, it shouldn't make much difference to how things work. From the factory the down pipe just dumps to the ground! 2 down pipes just means air can always get in.

**powerscol** · 05-08-2021, 08:31 AM

Originally Posted by RickLight

Yeah, it certainly means dropping the coroplast! I'm building quite a list of tasks for when it comes off.

The distance from tank outlet to floor may vary by rig, but it won't be large. Even if it's level, it shouldn't make much difference to how things work. From the factory the down pipe just dumps to the ground! 2 down pipes just means air can always get in.

The only issue with the double down pipe is wont stop the sloshing loss when your tank is pretty full, Every time you start or stop and go up or down a hill where the tank sloshes, a small amount will slosh out through the double down pipe vent. If this becomes a problem you might want to consider what I posted at the first part of this thread and you don't need to drop the coroplast either.

**RickLight** · 05-08-2021, 09:00 AM

Originally Posted by powerscol

If this becomes a problem you might want to consider what I posted at the first par of this thread and you don't need to drop the coroplast either.

I modeled my current 'fix' on that post back in 2019. I'm glad yours is working well, mine is a partial success. That's why I'm posting so much, real life beats theory.

Mine won't draw air due to the large amount of water in the pipe. I'm concerned the repeated flexing of the tank will shorten its life, and that blowing into it is less than ideal cleanliness.

**powerscol** · 05-08-2021, 09:27 AM

Originally Posted by RickLight

I modeled my current 'fix' on that post back in 2019. I'm glad yours is working well, mine is a partial success. That's why I'm posting so much, real life beats theory.

Mine won't draw air due to the large amount of water in the pipe. I'm concerned the repeated flexing of the tank will shorten its life, and that blowing into it is less than ideal cleanliness.

The solution to the pipe full of water and not drawing air is to simply open the low point valve momentarily and drain the pipe. If you concerning about the siphoning issue run the pump momentarily while you do it. or after unsung the pump for a short time, then open the low point drain valve, I assume you do have one. I have had no issues with mine collapsing the tank.

**RickLight** · 05-08-2021, 09:40 AM

None of that helps, it just continues to siphon and collapse the tank further. Once it gets down to somewhere around half there is enough suction to clear the line and let water in.

It's odd that our very similar rigs should behave so differently. If I get too much water loss after going to the double down system I guess I can do 2 valves.