It may or may not be located near the pump. Many spas have adjustable topside air controls, which introduce air into the jets. This is also a convenient location for adding an ozonator. The ozone is drawn in, and mixed with the water via the spa jets. All spas have a heating system of some kind, and most are electric.
Water is warmed as it passes through a heat exchanger.
Occasionally, spas have external heaters, which are usually gas fired. Jets H Powered by the pump, the hydrojets of your spa provide the soothing massage action. Your spa may be equipped with just a few, or many, depending on the design. Many spas allow the controlled mixture of air, along with the water through the jets, as describe above. Check Valve F Check valves are located on the output lines of air blowers and ozonators.