The other two spouts on the soda tower are for cold water and seltzer.
Items needed to make this happen:
Remote chiller - 2 flavor
McCann's Big Mac Carbonator (or similar item)
Carbon dioxide CO2 tank with regulator
water pressure regulator
connectors, tubing, and fittings, 1/4" and 3/8"
Water is carbonated by pressurizing it with carbon dioxide and then chilling it. The best way to pressurize water in a soda fountain application is with a carbonator. The carbonator forces (pumps) water into a pressurized cylinder containing CO2 and keeps it there until the valve is opened on the draft arm which allows the carbonated water to flow out. Periodically a the water pump is restarted when a float valve senses low water level in the pressurized cylinder. Water can dissolve ore CO2 when the pressure of the CO2 is high and the temperature is low (but not freezing). The chiller is a water bath that is cooled by a refrigeration system and there are tubes running through the water bath to cool the fluids running through the tubes. The chiller can support one or multiple flavors or types of fluid that is cooled depending on how it is designed. My set-up uses two flavors - plain cold water and carbonated cold water.