Air control systems are usually found in older models of hot tubs. If you want to know how your hot tub is controlled (through air or electrical/digital) it is easily identified. Air controls will have large buttons on your topside control with a thermostat control. Air systems are also called pneumatic systems and they use electro-mechanical time clocks to control functions such as filtration and heating. Little air bellows in the topside air buttons control the functions of the hot tub by means of a switch. The buttons are connected with air tubing. Air control replacements are still very reliable and well made. They are also less expensive than digital controls but don't have as wide of a variety for functions. It is possible to replace air control systems with digital control systems thus upgrading them.
