Fresh water tank oveflow lines will not stop leaking

Skidus1 wrote:
I installed 90 degree valves on both of my fresh water vent lines, when I see water running out of them I turn off the hose then turn both valves to stop any water loss. Keeps it in the tanks until I get set up camping. Just have to remember to open the valves after a bit of water use so the tanks can vent and not collapse.

I'd rather install a one way valve than a manual one, what if you forget to open it? I suppose the water pump will just starve, doubt it has sufficient power to collapse a tank.

I installed 90 degree valves on both of my fresh water vent lines, when I see water running out of them I turn off the hose then turn both valves to stop any water loss. Keeps it in the tanks until I get set up camping. Just have to remember to open the valves after a bit of water use so the tanks can vent and not collapse.

I believe there is far more likelihood of collapsing the tanks. DAMHIK

dedmiston wrote:
Solution Number 1: "Yeah, that happens sometimes with these units. To break the flow of the siphon, just hold the end of your compressor hose against the vent line and give it a couple of short blasts to clear the line."

That worked just OK, but I knew it was a horrible idea to blast air into the tanks and risk bursting them.

Dripping finally stopped after 1.5 days. I believe I overfilled tanks (filled until water dripped from overflow hoses). I believe once several gallons were used (to below overflow hoses), siphoning/dripping stopped

dedmiston wrote:
I used to have the same problem where my vent lines would create a siphon because they were lower than the bottom of the sealed belly. We tried a couple of things with various success.

DISCLAIMER: The kind folks at Giant RV seem to have been dropped on their heads multiple times, so please don't judge me for their solutions with this warranty issue.

Solution Number 1: "Yeah, that happens sometimes with these units. To break the flow of the siphon, just hold the end of your compressor hose against the vent line and give it a couple of short blasts to clear the line."

That worked just OK, but I knew it was a horrible idea to blast air into the tanks and risk bursting them.

Solution Number 2: "We installed shutoff valves on the vent lines for both of your tanks. Make sure you open the valves while you're filling and then shut the valves when you're done. That way the water can't drain out anymore."

This was a pretty bad idea too, plus it was a pain in the butt to crawl down there to mess with the valves before/after filling. I also knew that this really didn't address the poor design of the vents.

Solution Number 3: I quit dealing with Giant RV and hired a mobile tech to install new vent lines that didn't curve or loop and vented the tanks up high instead of down low, the way a vent is supposed to work.

This worked.

I wish I had bailed on Giant RV a lot sooner.

I'd bet money it's a siphon like you describe Dave. You'll have to get to the lines above the clorplast and raise them up above the top of the tank, then there can't be a siphon.

I used to have the same problem where my vent lines would create a siphon because they were lower than the bottom of the sealed belly. We tried a couple of things with various success.

DISCLAIMER: The kind folks at Giant RV seem to have been dropped on their heads multiple times, so please don't judge me for their solutions with this warranty issue.

Solution Number 1: "Yeah, that happens sometimes with these units. To break the flow of the siphon, just hold the end of your compressor hose against the vent line and give it a couple of short blasts to clear the line."

That worked just OK, but I knew it was a horrible idea to blast air into the tanks and risk bursting them.

Solution Number 2: "We installed shutoff valves on the vent lines for both of your tanks. Make sure you open the valves while you're filling and then shut the valves when you're done. That way the water can't drain out anymore."

This was a pretty bad idea too, plus it was a pain in the butt to crawl down there to mess with the valves before/after filling. I also knew that this really didn't address the poor design of the vents.

Solution Number 3: I quit dealing with Giant RV and hired a mobile tech to install new vent lines that didn't curve or loop and vented the tanks up high instead of down low, the way a vent is supposed to work.

This worked.

I wish I had bailed on Giant RV a lot sooner.

Could just be the water expanding as it warms through the day.
Not knowing how the two tanks are plumbed together it is possible that one drains before the other.

Not hooked up to city water.......
No access to top of tank.....
I’m assuming the flat type of hoses coming from top of tanks are oveflow hoses

I’m Puzzled???.....

Do you have access to the top of the water tank?

If so check the path of the tubes.

I don,t think the overflow pipe would go to the bottom of a tank. never seen a overflow that was flat. IF your hooked up to a water source? I,d say your check valve is leaking threw keeping the tanks over full. but I really have no idea whats wrong.