What is the difference between an air pressure tank system and a constant pressure system?

The air pressure system allows for a draw off of water before the pump will start, depending on the size of the pressure tank will determine how much water may be drawn off before the pump will start. An pressure tank will only turn off to high pressure, this means if your water supply runs out, you need to manually turn the pump off.

The constant pressure system turns on almost immediately when you turn a tap on and will give constant pressure hence the name. This type of electronic controller will also shut power to the pump should you run out of water, this is called Run Dry Protection.

A pressure tank can also be connected to a constant pressure system pump, and be used as an energy saving devise, when sized correctly the pump will not turn on for small draw offs of water.