I have and underground water tank which recevies water from an above ground warter tank. I need to stop the above ground tank filling the uderground tank when the under ground tank is full. I cannot fit a traditionall ball cock valve in the below ground water tank. What do I do?
OK, quite a simple idea, and is sort of the reverse of a central heating auto vent valve. and a bit difficult to explain in words only but I'll try.
First you'll need a smooth, soft hollow ball. (like a tennis ball but without the fluff on the outside). I used a dog ball from a pet shop.
This should fit inside 3" pipe. so now you make up a valve chamber with a section of 3" pipe, with a reducer at each end such that the ball will seal against the inside of the reducer.
Mount this vertically. Immediately above the valve mount a tee piece. the side exit is your overflow. the top inlet is from your above ground water butt, fit a strainer in this somewhere to stop detritus entering the valve.
Exit from the valve is to your below ground tank and should be sealed.
In normal operation the water will enter the valve and the ball will float allowing the water to pass.
If the below ground tank fills up. the ball will float on the water and seal against the top reducer. Causing any further flow to exit at the overflow.
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