Any plumbers on here?

[Squadir]

Hey guys, I ran into a slight hiccup while hooking up 2 potable water tanks for my home.

One tank holds 600 gallons and the other 400 gallons. It was my thinking that because the 600 is taller that I needed a check valve on the 400 so that it does not over flow when both are filled due to the height of the water level on the 600 being 16" higher. Both tank outlets are plumbed together and lead to a main pump that supplies the house.

The problem that I'm having is that the 600 empties out all the way and the 400 remains filled, I was under the impression that when the water levels out in both tanks or is a little lower in the 600 that the valve should have been able to open letting water out and allowing both tanks to empty at an almost even rate.

The pump shuts off when the 600 is emptied because the float switch for the pump is in there. Below is a simple diagram of the water connections and the valve used.
The inlets have floats on them that shuts the water off when filled.

I currently have a spring type check valve in use and was under the impression that 10" or so of water should have had enough pressure to open the valve. The water level in the 400g tank is about 60-65" when filled.

Any ideas??

 

[TheEngineer]

My guess is that when the pump turns on it pushes the check valve closed on the smaller tank. Is the 400g tank sealed? If so, you shouldn't need a check valve.

 

[Mark Shelly]

If the valve is oriented as shown, When the difference in water pressure pressure from the higher left is high enough to compress the spring, water should flow from left to right . When it is the same or lower on the left, no water will flow either direction. It also suggests the extra pressure on the left is either not enough to open the valve, or if it did, the water level on the right did not rise enough before resealing to overflow. If the valve was turned the other way around, the water on the left should open intermittently to lower the level until to the reseal pressure differential height is met. Even then, the right would always be about that reseal pressure differential height difference higher on the right when the left is drained.
This is really a one way valve meant to flow in the direction of the arrow only.
I am not a plumber, but I have worked with pressure relief valves on large metal containers. But most of them worked to seal containers and release pressure either directly, while not allowing constant air flow (and its moisture) between the inside and outside of the container.

 

[Squadir]

Those pics of the valve were just to show what type of valve was used.
The water flow is right to left and the valve is there only to prevent the 400 from overflowing from backflow when the 600 is filled due to the difference in water levels but should ideally be open when the levels in the 600 drop. The problem is that the valve doesn't open even when the 600 is emptied and the 400 is full.
Anyone have any idea of the height of water required to break the seal on this type of valve?
Maybe a different type of check valve should be used like a swing arm type?

 

[TheEngineer]

Those pics of the valve were just to show what type of valve was used.
The water flow is right to left and the valve is there only to prevent the 400 from overflowing from backflow when the 600 is filled due to the difference in water levels but should ideally be open when the levels in the 600 drop. The problem is that the valve doesn't open even when the 600 is emptied and the 400 is full.
Anyone have any idea of the height of water required to break the seal on this type of valve?
Maybe a different type of check valve should be used like a swing arm type?

I'm 85% sure the issue is back pressure either from the pump or the house.

If we ignore the 600 gallon tank, you have a check valve that prevents water from entering the 400 gallon tank via the plumbing. You are relying on gravity to push the water out of the tank and to your pump. The pump is on the other side of the valve. Your house (or a pressure tank) is on the other side of the pump. Is that all correct?

If so, the pressure in your house/pressure tank will always keep that check valve closed.

 

[TheEngineer]

You can test my theory. If you can disconnect the tanks from the pump and your house you will see the levels equalize in the two tanks once the pressure in the line is relieved.

 

[Squadir]

i'll give it a shot when I get home later, thanks.
I bought a swing type valve to replace the spring though, it isn't spring loaded so it should serve the purpose that I require. I will run the test before I change the valve though.

 

[Squadir]

just an update:
when the line was disconnected from the pump the valve still stayed shut, may have been a faulty valve but when I took it off it worked fine when I pressed the seal with my finger and yes it was installed the correct way lol..... strange I never had this issue before with this type of valve.
I installed the swing arm type valve and it solved my issues.

Thank you for your input though :)