How Does a Self Defrosting Freezer Work?

Identification

• A self-defrosting freezer has a heater that warms up the cooling element in the freezer. This heat melts any frost on the cooling element, and the water drains out the back of the refrigerator into a drip pan, where it evaporates. New refrigerator models have a timer that only runs when the refrigerator runs, so if a refrigerator does not open much, the self-defrosting mechanism will not run as much to save energy. A refrigerator-freezer combination that has a self-defrosting mechanism in the freezer area only is called a partial self-defrosting unit, while one that defrosts the entire unit is called total self-defrosting.

Time Frame

• Automatic self-defrosting in modern refrigerators happens about every eight to 10 hours, but could be more if you open the unit frequently. Defrosting takes about 25 minutes. This short period of defrosting should not affect your food.

Benefits

• Refrigerators and freezers without a self-defrosting heater will have frost buildup, which requires routine melting. Self-defrosting eliminates this time-consuming and messy process. The freezer will remain frost-free, and food labels will stay visible without excess frost. Also, food will stay cooler and smell fresher, as the air in a self-defrosting freezer circulates more.

Disadvantages

• Though the defrost period does not affect food, items that contain enzymes, such as medical supplies, can be damaged from a slight change in temperature. These freezers are not suitable for laboratory settings. Because there is a heating element in the self-defrosting freezer, it has an increased complexity that can make repairs more frequent and costly. If the cover surrounding the heating element comes loose, the excess heat and power could present a fire hazard.

  Models without automatic, built-in sensors to determine when to self-defrost are not more energy efficient, especially if they are used frequently. The Energy Star Partnership Program found that automatic units used 24 percent more energy than manual-defrosting units, and users actually opened the self-defrosting refrigerators more, which led to further energy use.