Well pressure tanks create water pressure by using compressed air to push water down. When the valve opens, compressed air in the tank pushes the water out. Water is pushed through the pipe until the pressure drops to the preset low value on the pressure switch. Once the low setting is reached, the pressure switch communicates with the water pump, telling it to turn on in order to push more water into the tank and house. To determine the right size well pressure tank needed, you need to consider pump flow, pump run time and cut-in/cut-out psi.
What is pressure tank drop capacity?
The drop capacity is the minimum amount of water that the pressure tank can store and deliver between pump shutdown and pump restart. Do not confuse drop capacity with tank volume size. The bigger your tank, the bigger drop (actually stored water) you will have. A larger drawdown means a longer run time and fewer loops. Manufacturers generally recommend a minimum run time of one minute for the motor to cool down. Larger pumps and higher horsepower pumps require longer run times.
