An apparatus includes a compressor, a load, a heat exchanger, and a heater. The compressor compresses a refrigerant. The load uses the refrigerant to remove heat from a space proximate the load. The load sends the refrigerant to the compressor. The heat exchanger receives the refrigerant from the compressor. The heat exchanger transfers heat from a fluid to the refrigerant. The heat exchanger discharges the refrigerant to the compressor. The heater adds heat to the fluid.