Refrigeration Economizer System

If you have a large walk-in cooler or freezer, refrigeration costs can be reduced simply by taking advantage of cooler outside air. The device that handles this function automatically is called an economizer.

The Refrigeration System

In a typical refrigeration system, electricity is consumed by four major components: the compressor, condenser fan(s), evaporator fan(s), and access door defrosters (for reach-in coolers and freezers with glass doors). Energy used by the compressor accounts for the largest percentage of the total electricity consumed. An economizer reduces electricity consumption by reducing the refrigeration compressor run time. Studies show that a refrigeration compressor is on 40% to 50% during the winter months. Most of this time, however, the outside air is cold enough to satisfy refrigeration needs. If the outdoor air is blown directly into the space to be cooled, the compressor may not need to run at all, resulting in considerable cost savings.

How the Economizer Works

An economizer is a relatively simple mechanical device with sophisticated controls. The economizer constantly monitors outdoor air temperature. It automatically draws outdoor air into the cooler/freezer whenever it is cold enough to substitute for compressor-generated cooling. During this time, the compressor and condenser fan(s) are shut down and a fan and damper system is used to transfer outdoor air into the cooler. Since the fans used to transfer this air use much less energy than the refrigeration cycle, substantial energy savings will result. Walk-in cooler economizer packages come with different options, such as evaporator fan control, access door defrost controls and enthalpy monitoring equipment.

Is It For Me?

The economizer is an ideal energy-saving device for those facilities where refrigeration represents considerable energy consumption and these systems are kept at 38° or higher. If you have a large space to cool or walk-in coolers, you should consider installing an economizer. In many instances, economizers have shown paybacks in less than two years.

Local climate also plays a factor in evaluating economizer effectiveness. The farther north your facility location, the more often you will be able to take advantage of free cooling. But even in the southern United States, there are many days and especially nights when free cooling is available from outdoor air.

    *Design B., Four Pole, Three Phase
  **Assumes 100% Full Load
***Payback is the difference in the First Cost of the High Efficiency Motor vs. the Standard Motor, divided by the Difference in Electricity Cost.