A water chiller is a device consisting of a compressor, a condensor, a thermal expansion valve, and a refrigerant evaporator coil enclosed in a steel shell. It’s used as a way of adding central air conditioning to a structure heated by either hot water or steam. The water in the system is pumped through the shell, where it is cooled by the evaporator coil, and circulated through the radiators or convectors for cooling and dehumidification.
The boiler and water chiller are available packaged in a single unit, or they may be installed as separate units. In a hot-water heating system, the same piping can be used to carry both the hot water and chilled water to the radiators or convectors. The room radiators or convectors are individually controlled to permit temperature adjustments. Steam piping should not be used to carry the chilled water.
When a water chiller is installed as a separate unit, the chilled water should be piped in parallel with the boiler. Appropriate valves should be installed to prevent the chilled water from entering the boiler.