1. jerrymyersmills

    Thread Starter New Member

    Mar 22, 2011
    I have bought a water tank for water storage due to irregular supply.
    Sometimes i have to stay back and turn the tap off when it is full at midnight .I want try and install a 'sensor' inside the water to turn the tap off or by closing solenoid valve when the water reaches the desired threshold.
    Can anyone help me out with project since this is one is very dear to my heart.
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Is the flow and pressure in the range of a float valve?
  3. strantor

    AAC Fanatic!

    Oct 3, 2010
    yup, float valve. or if you want to make it all fancy-schmancy, float switch, going to a solenoid valve.
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
    I haven't seen any lately and don't know where I got them - maybe Goldmine - but I've got a number of float switches. Thy wouldn't handle much current though.

    You can get a decent float switch from a wholesale HVAC supplier, they use them in the condensate catch pans as an emergency cutoff if the drain gets plugged. When it sense the water level has risen too high it breaks the 24V control circuit that goes to the condenser (outside unit) motor contactor effectively stopping any more cooling from going on.

    Some boat supply stores will also have float switches but they may be larger.

    Another alternative is just two electrodes hooked up to a sensitive op amp circuit that feeds a transistor or MOSFET that controls the relay.

    The big question is do you have a way to get something like one of these inside the tank?
    I suppose a hole could be drilled and if you're going with the "two bare wires" method they could be put through a rubber stopper if there's no pressure on the water in the tank or something could be rigged up with a threaded plug with a hole and epoxy glue. You actually wouldn't need two wires if it's a metal tank, a single wire could be the pickup and the tank as the other electrode.
  5. marshallf3

    Well-Known Member

    Jul 26, 2010