What type of system uses chilled water to control indoor temperature?

A chilled water system is designed specifically to utilize chilled water as the primary means to control indoor temperatures. In this system, water is cooled by a chiller and then circulated through pipes to air handling units or fan coil units throughout a building. These units use the chilled water to absorb heat from the indoor air, effectively lowering the air temperature in the space. The cooled water returns to the chiller for re-cooling, allowing for continuous temperature control.

In contrast, split A/C systems, heat pump systems, and window units operate on different principles. Split A/C systems typically use refrigerant for cooling and involve a separate indoor and outdoor unit, while heat pump systems can provide both heating and cooling but still primarily rely on refrigerants. Window units are compact air conditioning systems that also utilize refrigerant for cooling rather than a chilled water process. Thus, the use of chilled water specifically indicates that the answer is indeed a chilled water system.