Maintain hydronic based heating and cooling systems (with associated components); compliance, inspection, installation, maintenance and operation of hydronic based systems include: centrifugal chillers, fan coil units, outdoor supply air units, steam to liquid heat exchangers, heating hot water pumps, chilled water pumps, domestic water pumps. M aintain, repair, replace, and install components for chilled water, hydronic heating, and domestic cold-water systems such as pumps, motors, variable frequency drives, heat exchangers, valves, and steel and copper piping; Maintain prescribed level of chemical treatment in closed loop systems .