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Energy Saver: Refrigerator & Freezer Set Points
(continued ...) After a day or two, take readings from thermometers. Adjust for the error that you previously found. Compare that to the FDA's recommendations. Is it too warm? Lower the set point a little bit. Is it too cold and wasting energy? Increase the set point a little bit. Repeat the 24 hour test and recheck. If this refrigerator or freezer is a single temperature compartment, then you are done for now. Mark your calendar to repeat the same check about a year from now.
For combination refrigerator and freezer appliances we have a few more steps. There may be a common control set point for both compartments. There may also be a diverter control of some kind. We'll talk about the diverter type in moment. For common control set point, the appliance manufacturer has engineered the difference into the design. But we need to find the worst case scenario between the freezer and the refrigerator.
Complete the refrigerator compartment testing and make the adjustments indicated before. With the refrigerator compartment set, repeat the same testing described earlier in the freezer compartment. Is the freezer at 0 F (-18 C)? If yes, great! The appliance designers got the split exactly right and you're done.
Is the freezer too cold (below 0 F or -18 C)? Unfortunately you are still done because we do not want to raise the common set point and have the refrigerator portion rise above 40 F (4 C). Is the freezer too warm? Lower the common set point a little bit and retest until the freezer is at 0 F (-18 C). And again this is unfortunate because these two possibilities mean you are wasting some energy for the life of the appliance. But you'll know your food is as safe as it can be stored in your appliance while using the least amount of energy possible.