This happened to me. I filled the FW tank and stopped when water came out the overflow. I drove about an hour and checked the tank at a pit stop. The FW tank was EMPTY!
I think once the siphon started the vacuum squeezed the tank dry, like a juice-box. I am going to install a Vacuum Breaker in the highest point of the overflow hose. I will then test it in my driveway and report back.
Did you reinstall the check part of the anti-siphon valve? If you didn't, does water leak out of it when the tank is full?
I only removed the spring & plastic check valve in red below.
The big gasket blocks the small holes from leaking water.
The Vacuum breaker is in the overflow line, at the top of the tank. It did not leak. I will be checking it again at the next FW fill.
The fresh water tank on my Hemisphere was doing the same thing. I had about 6-8 inches of vent hose hanging below the underbelly cover of the trailer. I installed a valve on the end of the vent tube and once I have the tank full, I close the valve. After I arrive at the site and have run about a gallon of water out of the tank, I open the vent valve. This last step is important because you risk collapsing your tank if you run the water pump too long with the vent closed.
__________________ Matt
2018 F250
2014 Salem Hemisphere 282RK
The fresh water tank on my Hemisphere was doing the same thing. I had about 6-8 inches of vent hose hanging below the underbelly cover of the trailer. I installed a valve on the end of the vent tube and once I have the tank full, I close the valve. After I arrive at the site and have run about a gallon of water out of the tank, I open the vent valve. This last step is important because you risk collapsing your tank if you run the water pump too long with the vent closed.
I end of doing this also.
I would like to try this vacuum break item in the future.
[QUOTE=Lowes48fan1;1900108]The fresh water tank on my Hemisphere was doing the same thing. I had about 6-8 inches of vent hose hanging below the underbelly cover of the trailer. I installed a valve on the end of the vent tube and once I have the tank full, I close the valve. After I arrive at the site and have run about a gallon of water out of the tank, I open the vent valve. This last step is important because you risk collapsing your tank if you run the water pump too long with the vent closed.[j4
Will the fill port provide the make up air so the tank does not collapse.
My tank has two overflows off the top of the tank but they do not extend down into the tank so I have never had a syphon issue. When new the two overflows where open below the floor so I installed duck bill check valves on them to keep bugs out. I have not had the tank collapse.
I had the same problem with my 2911 Georgetown and fixed it by drilling a 1/8" hole in the top of the overflow tube, under the clamp attaching it to the top of the compartment. The hole prevents a vacuum from draining the tank and the small hole with the clamp on top of it is well protected.
2018 FR3 28DS | Boondock 99% of the time
Linear Mode
