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A poorly operating refrigeration system can waste energy in several different ways. A maintenance inspection should include tasks that ensure the system is operating properly and efficiently. A major impact on energy consumption is operating a system with a low refrigerant charge. A 23 percent refrigerant un-
dercharge could result in a 52 percent efficiency loss. A maintenance inspection must always include verifying the system is operating with an adequate amount of refrigerant.
What To Look At
Systems operating with higher than normal discharge pressures waste energy. The operating discharge pressure of a system needs to be checked and, if excessive, returned to normal operating pressures. Systems with an air-cooled condenser must be clean as required and water-cooled condensers checked for fouling and cleaned as required. Operating a system with a dirty condenser coil can consume up to 37 percent more energy.
System run times can be kept at a minimum by operating with a proper door seal. Door gaskets, hinges and the integrity of the door needs to be checked as part of any maintenance inspection. Torn or worn door gaskets need to be replaced; broken or loose door hinges need to be repaired; and any other issues with the cabinets door(s) needs to be identified.
The condition of the evaporator coil and fans needs to be part of the inspection. Excessive icing on an evaporator coil or a defective fan(s) degrades the heat exchange ability of the coil and wastes energy.
The defrost cycle of low-temperature systems need to be inspected. Over time, these defrost cycles can fail to operate correctly, either the defrost cycle becomes too long or too short, both leading to an inefficient defrost and potential waste of energy. Another area to examine on low-temperature systems is the temperature controls. A defective or misadjusted temperature control can cause a system to operate at a lower case temperature which can lead to excessive run times. Operating a system at a lower case temperature may not be perceived as a problem, but is a waste of energy. Operating a system at -20˚F costs more money than operating it at -10˚.
These are just some system operating conditions a contractor can inspect to help ensure a system is operating properly and not wasting energy. Adding this approach to selling and conducting a maintenance program is definitely a win-win scenario for both the contractor and customer.
Publication date: 8/6/2012