Simple Timer Can Prevent Short Cycling in Cooling Systems

Executive summary

A leading cause of loss in air conditioning and refrigeration is compressor failure.  Because these failures occur during periods of peak usage, repairs are not only costly; they come at a time when parts and repair service may not be immediately available. Every year, Hartford Steam Boiler pays many claims for tens of thousands of dollars each because of compressor failures that inconvenience customers and interrupt business.
The cause of many such failures is short cycling, meaning that the compressor is called back into operation after having been stopped for only a brief period of time. This results in the compressor starting against nearly full high side discharge pressure, causing severe loading of both mechanical and electrical elements of the compressor..

The full article

Simple Timer Can Prevent Short Cycling in Cooling Systems

Why Short Cycling Is Destructive

A compressor should remain off for a period of time necessary for the discharge pressure to dissipate. This occurs by expansion of refrigerant from the high-pressure side through the expansion valve/s. If this process is not completed, the power needed to start the compressor against that pressure will result in high starting currents and high stresses on mechanical parts.
When this occurs during periods of high utilization, the already hot electrical components, subjected to higher than normal starting currents, go to even higher temperatures and premature failure. Even when the electrical parts do not fail, the higher stress imposed on the mechanical elements will lead to failure.

Lessons Learned

It is only necessary to allow a compressor to remain at rest for a sufficient period of time to dissipate high side pressure to avoid the problems associated with short cycling. The least costly way to do this is to install a delay timer in the compressor starting circuit. Such timers are available from any number of electrical or industrial suppliers and can be had in configurations specifically designed for compressor start delay service.
Disclaimer statement:

All recommendations are general guidelines and are not intended to be exhaustive or complete, nor are they designed to replace information or instructions from the manufacturer of your equipment. Contact your equipment service representative or manufacturer with specific questions.

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