Chilled Water Air Conditioning
With chilled water air conditioning, the refrigeration machinery (the compressor, condenser, evaporator, etc.), doesn't directly cool the air.
The evaporator cools water to about 45°.
That chilled water is pumped to cooling coils in the areas being cooled, and a fan draws the air in those areas through the chilled water coils, cooling the air.
In comparison, with standard air conditioning, the evaporator coil directly cools the air.
The refrigerant flows all the way to the air handlers in the areas being cooled, and a fan draws the air in those areas through the evaporator coils, cooling the air.
With chilled water air conditioning, the compressor is usually mounted on a rack or frame, within a few feet of the evaporator that cools the chilled water.
If the condenser is water cooled, it's usually mounted on the same rack.
If the condenser is air cooled, it will be installed outside the building.
One advantage of chilled water air conditioning is that if the chilled water piping leaks somewhere in the building, only water is lost, and repairs only require plumbing work.
In comparison, with standard air conditioning, a leak in a refrigerant line inside the building will probably require brazing, leak testing with nitrogen, evacuation of the system, and recharging with a refrigerant that is a lot more expensive than water.
Another advantage of chilled water air conditioning is that if air stops flowing through the cooling coil, the chilled water will simply return to the chiller.
Since the water will not have picked up any heat, it will still be cold, and the chiller will respond by unloading and turning off.
With standard air conditioning, if air stops flowing through the cooling coil, there is a possibility that liquid refrigerant will return to the compressor and damage it.
Another advantage of a chilled water system is that in a building like a hotel, hundreds of rooms can be cooled individually, with each room having it's own chilled water air handler, all supplied by one chilled water system.
If you're troubleshooting a chiller, our
Air Conditioning and Refrigeration System Evaluation Manual
has cycle diagrams for air-cooled and water-cooled chillers, and guidance on evaluating chiller operating pressures and temperatures.
I hope this page has helped you understand chilled water air conditioning, and please, feel free to contact us with any specific HVAC questions you might have, including questions about air conditioning on Guam, or refrigeration on Guam.
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