Fresh water Tank venting continuosly

James Walton 310

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Joined
May 5, 2024
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4
On our Reflections 150 Series 230RL We filled the Fresh Water tank until water flowed from the Overflow/Vent Line.We checked the Tank Level from the Monitor and it read 100%. We disconnected and drove 45 mins to check in at the State Park. Once set-up at our camp site we checked our Fresh Water Tank Levels and the Tank was @ 1/3 . All of the Valve’s were set for Dry Camping as outlined on the Nautilus Controller when we left the Filling Station. What is our issue ?
 
As [MENTION=10506]jkwilson[/MENTION] said, you are losing water because it is being siphoned from the fresh water tank by the overflow valve. I had the same issue, put a shut off valve on the overflow line.
https://www.amazon.com/gp/product/B08DSF4TH3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
The downside is you have to open it when filling and using the freshwater tank and close it when traveling to prevent the siphoning. I have read that if you use the pump to draw water from the fresh water tank with the valve closed you could "implode" the tank. I wouldn't think the pump is that strong but who knows.
I think it is annoying that GD did not take this into account when designing/building their trailers.
Good luck and welcome to the forum.
 
As [MENTION=10506]jkwilson[/MENTION] said, you are losing water because it is being siphoned from the fresh water tank by the overflow valve. I had the same issue, put a shut off valve on the overflow line.
https://www.amazon.com/gp/product/B08DSF4TH3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
The downside is you have to open it when filling and using the freshwater tank and close it when traveling to prevent the siphoning. I have read that if you use the pump to draw water from the fresh water tank with the valve closed you could "implode" the tank. I wouldn't think the pump is that strong but who knows.
I think it is annoying that GD did not take this into account when designing/building their trailers.
Good luck and welcome to the forum.

If the check valve in the pump fails while hooked to city water or you attempt to power fill the tank, the tank can inflate and fall out of the trailer if such a valve is closed. I’d reconsider a valve on the overflow. GD has switched to a dual overflow so the siphon is broken.
 
Thanks to everyone who has responded. It is so comforting to know I have each of you and your knowledge to rely on. You are the Best !!
 
James,

After I have filled the tank, I set the valves to "Dry Camping" and run the outside shower (using the pump) to pump water out of the tank until the siphoning stops. Doing this breaks the siphon (fills the overflow tube with air again) and we don't loose any water afterward.

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Rob
 
It is good to know that GD has addressed the siphoning issue. I had not considered the backflow issue, but as the only time the valve is closed is when I am traveling I will stick with the shutoff valve. Thanks for the warning though.
 
We suffered through the same anomaly until I read, and re-read, the reasons a tank starts syphoning when it is too full. Ever since I educated myself we now leave with about 2/3 tank of water and arrive at our destination with close to the same amount (allowing for water usage along the way).
It is far cheaper, and much less labor intensive, than installing extra shut-off valves.
 
Last edited:
@ Second Chance

After I have filled the tank, I set the valves to "Dry Camping" and run the outside shower (using the pump) to pump water out of the tank until the siphoning stops. Doing this breaks the siphon (fills the overflow tube with air again) and we don't loose any water afterward.

Nice tip!
 
Here’s a pic of how the dual tube, anti-siphon arrangement is constructed, if anyone is curious. The port is on the upper side of the tank, so they elbow up above the tank and then over to two down tubes.

8C43BC0C-090E-4AE0-9A0D-C8425B846ACA.jpg

Sorry the pic is (always) turned on it’s side.
 
The valve is a solution, but not without a certain element of risk: if you forget to open it when filling the tank, there can be dire consequences.
 
Installing a shark bite valve takes literally seconds.

Here is the result of a shark bite valve

IMG_0494.png

Note the white valve with the handle closed on the overflow line.

You don’t even have to be filling the tank for it to happen. If the pump check valve fails it will happen too.
 
That’s not the valves fault, obviously it wasn't opened when it should have been.

The odds of forgetting a valve hidden under the trailer are so high it’s virtually guaranteed to happen. 99% of the time you’ll remember it.
 
That is what brother label makers are for. I have remove before flight tags on my city water fill for when I close the valves. Makes it so I can’t easily forget (and labels on the water pump too to make sure valves are open).
 
Yeah, that might work, as long as you don't get too distracted. :) Heck, there are stories of people driving off with their power still hooked up, stairs still down, awning not retracted, or antenna still up. If things that obvious get forgotten, what chance does a little label stand? :) IMO, the more undesirable the consequences, the higher the chances for doing it. :)
 
Yeah, that might work, as long as you don't get too distracted. :) Heck, there are stories of people driving off with their power still hooked up, stairs still down, awning not retracted, or antenna still up. If things that obvious get forgotten, what chance does a little label stand? :) IMO, the more undesirable the consequences, the higher the chances for doing it. :)

Yeah, personally I wouldn’t risk it either. Why add to the list of pitfalls you have to avoid? If you have the old venting arrangement, just drop the coroplast and replace it with the new version that I posted earlier. It cannot siphon. Now, you can still lose water from the trailer leaning to the drivers side, but you could get creative on that as well, and still not lay a trap for yourself.
 
On our Reflections 150 Series 230RL We filled the Fresh Water tank until water flowed from the Overflow/Vent Line.We checked the Tank Level from the Monitor and it read 100%. We disconnected and drove 45 mins to check in at the State Park. Once set-up at our camp site we checked our Fresh Water Tank Levels and the Tank was @ 1/3 . All of the Valve’s were set for Dry Camping as outlined on the Nautilus Controller when we left the Filling Station. What is our issue ?

New to Grand Design. Took our first dry camping trip and had the same thing happen. Thought it was the gauge fault. Since seeing your post I realized the problem. Went out and filled the tank to overflow and sure enough it kept draining/siphoning. Tried a couple of things but nothing broke the siphon. Then I opened the main drain for the fresh water tank for a second, open then closed as fast as I could and the siphoning stopped. It's been awhile and hasn't started up again, maybe fixed? Trailer is just sitting, not traveling so I don't know if that makes a difference. Dan
 

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