Liquid chillers are cooling devices designed to remove heat from processes such as spot welding, plastic molding, laser systems, or any other process that generates heat which needs to be removed.

Liquid chillers range in size from a fraction of a ton to over 100 tons. Units of less than 30 tons are usually considered as portable. This comparison will only consider portable models. Many of the manufacturers making portable models also make the larger, fixed installation units.

Liquid chillers come as air cooled and water cooled models. The main parameter for these systems is the amount of heat it is capable of removing. The common ratings are: tons, BTUs, or watts. One ton = 12,000 BTUs = 4000 watt-hour (4 kW hr). These are approximate values.

For portable chillers, the ratings go from 1/4 ton (1 kW hr) to 40 ton (160 kW hr). Another important parameter is the temperature range that the process fluid has to be at. 0 C or 32 F is typically the low end for most models. Special units that go to -40 C or F are available. The temperature of the environment is a factor, particularly for air cooled models.

The power required to operate a liquid chiller is high. The horsepower of the refrigerator pump is similar to the cooling capacity in tons. Thus a one ton chiller will have a one hp motor. The process fluid often has chemical additives such as glycol with water, deionized water, or special cooling solutions such as 3M FCC because of the required process temperature. This reduces the cooling capacity of the fluid, which means that a greater volume of fluid has to be pumped and a larger capacity system is required.