HotSpring Spa Air Valve 1-12" Assembly. The Hot Spring air control valve, located on the filter compartment, allows the spa user to control/adjust the amount of air that is supplied to all the hydrotherapy jets in the spa. The amount of air is controlled/adjusted by turning of the air lever. The more air, the stronger the jet pressure feels. The force of the water pressure rushing through the individual jets in a venturi effect inducts the air through the air valve.