Heat raising systems, such as gas boilers or heat pumps, support centralized cooling systems by providing hot water for the heating coils in the air handling units. During the heating season, the hot water is circulated through the coils to warm the air, which is then distributed to the building spaces. The heat raising system can also provide hot water for other building services, such as domestic hot water or space heating. In some cases, the heat raising system can be designed to recover heat from the chiller condenser, improving overall system efficiency.