Chiller Basics

A chiller is a water-cooled air conditioning system that cools inside air, creating a more comfortable and productive environment. Chillers are also used in the manufacturing environment to provide "process" cooling to equipment in an effort to maximize productivity.
With large facilities, such as commercial buildings, hospitals, universities, government facilities and theme parks, the cost of energy to generate cooling in excess of 50 tons is cost prohibitive with air-cooled units. Water-cooled chillers produce higher tonnage at lower costs per ton, creating greater energy efficiency. A typical home has 3-5 tons of cooling capacity.
How a Complete Chiller System Works
ChillerHeaderChillers circulate chilled water to air-handlers in order to transfer heat from air to water. This water then returns to the evaporator side of the chiller where the heat is passed from the water to a liquid refrigerant (freon). The refrigerant leaves the evaporator as a cold vapor and enters the compressor where it is compressed into a hot vapor. Upon leaving the compressor, the vapor enters the condenser side of the chiller where heat is transferred from the refrigerant to the water side of the condenser where it is circulated to an open cooling tower for the final removal of heat via evaporation in the cooling tower.
What is Chiller Efficiency?
Chiller efficiency is the amount of energy (electricity) it takes to produce a "ton" of cooling. It is PageContent_ChillerBasics_00 (1)expressed as kw/ton. All chillers have a designed kw/ton efficiency that was established when the chiller was commissioned. Plant design, water treatment, maintenance practices, chiller age, cooling tower design, cooling load and plant operations dramatically effect chiller operating efficiency and operating costs.
Chiller Operation, Service and Maintenance A chiller "operator" is known by several titles, including Stationary Engineer, HVAC Engineer and Service Technician. Operation and maintenance includes collecting and logging data from various gauges, controls and meters located on or near the chiller. Service contractors, who specialize in equipment repair, are contracted when major repairs or overhauls are required.
There are essentially three types of maintenance performed on chillers; water chemistry, mechanical maintenance and operational procedures. Water chemistry is maintained to keep proper balance and minimize the effects of scale, corrosion and micro-biological / debris fouling. Mechanical maintenance includes proper lubrication, adequate liquid refrigerant, oil levels and pump curve tests. Operational procedures include eddy-current tests, oil analysis, calibration of gauges and meters and other various tests.

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