Boiler & Two-Pipe to Four-Pipe Conversion Upgrade of the existing boiler to new more efficient technology, adding an air separator to the system to assist with air removal. The system was converted from a two-pipe to a four-pipe so that changeover from heating to cooling is simpler and quicker. Chiller Replacement Project consisted of upgrading the existing chiller with the air-cooled condenser located on the roof to a air-cooled chiller on-grade. All of the interconnecting refrigerant piping between the condenser and the chiller was removed. The controls were upgraded to allow connection of the new equipment to the existing control system.