When you improve chiller efficiency, you can have better control of the chiller and the air conditioning in the building, and the chiller will also last longer.

The recommendations here are for centrifugal chillers. If you find a method that seems like it would work for your facility, contact the manufacturer of the chiller for detailed guidelines on how to implement it.

One way to improve chiller efficiency, especially if the chiller is old, is simply to replace it. Modern chillers are designed to be more efficient, they’re available for use with non-ozone-depleting refrigerants, and they can use alternative energy sources.

Another way to improve chiller efficiency is to automate the controls of the chiller system. This will automatically coordinate and control all the system components - chilled water pumps, chiller, tower fans, etc. - in a way that will optimize efficiency.

Modernizing the controls is another way to improve efficiency. A modern control center will give you much more precise control of the chiller, and can provide a lot more information about the operating characteristics of the system. This will also help you keep a more detailed log, and help you spot problems while they’re still small.

Another way to improve chiller efficiency is to add a variable speed drive (VSD). With modern controls, VSD will optimize chiller motor speed and vane position to the exact cooling load and reduce the power consumption of the chiller.

You could also improve chiller efficiency by replacing the compressor-motor assembly. This would make a lot of sense if the evaporator and condenser barrels are still in good shape. A modern compressor would be more efficient, and a new control center would be included in the retrofit, which would be another benefit.

Operating the chiller at higher leaving chilled water and lower entering condenser water temperatures is another way to improve efficiency. Operating at higher leaving chilled water temperatures lowers the compressor head resulting in a lower amp draw. Operating at lower entering condensing water temperatures also lowers compressor head and lowers the motor amp draw.

Of course, never operate outside the design conditions of the chiller system.

Once again, if one of these methods sounds feasible, contact the chiller’s manufacturer for details and guidance.

Publication date: 02/08/2010