The springs are only about a half pound and maybe even less. I suspect the tank contents are splashing back through the elbows and against the valve seat. Either that or once the tank contents get above the connections it just seeps back through the check valves because there is no positive seating. The 1/2 pound springs are not much of a positive seat. The valves I bought are actually plastic and I think made by Qest. They are used on trailer water heater outlets and work the same as the brass valves. The valves should be good for 60 to 100 PSI. However I don't have 60 to 100 PSI to backseat the valve hard against the seat. So the liquid contents of the tank seap back through the valves and down the hoses to where you would connect a garden hose to flush the tank. Not very sanitary when connecting the garden hose or in my case when the contents froze and cracked the PVC nipple at the ball valves.
