Water only working when tank is Full?

[TheLooks]

The tanks may be the same size. I have 2 in my Jayco TT and the line connecting them is smaller then that. I don't like how mine is either. It pulls from just one of the tanks and fills in the other. Low point drains are separate for both.

 

[TheLooks]

I am going out on a limb and guessing that with the tanks full, the pump has less vacuum pulling on the supply line and when the water gets about halfway it has to lift just enough to pull a air leak in a fitting on the supply line.

 

[Kevin D Pem]

I am going out on a limb and guessing that with the tanks full, the pump has less vacuum pulling on the supply line and when the water gets about halfway it has to lift just enough to pull a air leak in a fitting on the supply line.

That was how we got here! I am now thinking a vortex is forming in one of the tanks. This shows how lame the engineering is in the RV INDUSTRY.

So what do you think, move the why to the drain bung on the main tank, and take that why out of the crossover??? New hole in floor for the drain to go and a plug for the old hole?

 

[TheLooks]

I can't see if that is a Y or it is just another penetration next to the xover pipe......It is nice to have a little water stay in the tank to contain crud but if you are wanting to use every ounce of water it is not so good.....It really should be no problem to put another fitting in lower if needed.

 

[Kevin D Pem]

So was thinking about this while sleeping, I get answers that way!

I will tell you what I see wrong that might help. Even if it fails to help on this project it would help with another issue you have not addressed yet.

The fill hose has a dip! This dip makes filling the tank slower. Simply let the strap down till the dip is gone. I like to strap fill hoses to a split piece of pvc pipe to keep them straight.


If your fill fitting has a cap try taking the cap off and pump the tank down. If you no longer suck air, your tank vent hose has a dip that has water in it. Make sure the vent hose is free of dips.

I see the problem as one tank has a proper vent while the other doesn't. A dip in the vent will create a small but important vacuum in the tank allowing one tank to drain unequally. This new to the system problem, likely manifested itself when you fully filled the tank and that allowed water into the vent hose.