|As the pump fills the tank with water, the air above the diaphragm is compressed. This increases the pressure in the tank and causes the pressure switch to turn off the pump.
|When water is drawn from the tank, pressure inside the tank decreases until the pressure switch starts the pump. The amount of water delivered between pump cycles is called drawdown. The greater the drawdown capacity, the less the pump needs to run, saving energy and money, and extending pump life.
|As water is drawn from the tank, the reduced pressure starts the pump and refills the tank.