Empirical testing has shown that the optimum time to defrost is when the evaporator loses about 10 percent efficiency. Traditional methods of defrost, based on time, cannot ascertain this loss of efficiency and will either waste time and energy in excessive defrosting, or never fully defrost the evaporator.
As new stores are built and older systems in existing stores replaced, an approach called secondary refrigeration is gaining wider acceptance and is steadily increasing in numbers.
Centralized refrigeration systems have been in use for years. Distributed systems, on the other hand, are one of the newer commercially adopted refrigeration technologies.
Actually, frost on the suction line only indicates that at the location where the frost is present, the suction line piping is below the dew point temperature of the surrounding ambient air and at or below 32°F. That’s it. It is neither an indication of a properly operating system nor a system defect.
The actual frequency and tasks performed will vary from system to system. However, here are some generic maintenance tasks which can be applied to many refrigeration systems. These tasks can be divided into two groups: one for maintaining the cabinet and one for maintaining the refrigeration system.
Mechanical refrigeration is accomplished by continuously circulating, evaporating, and condensing a fixed supply of refrigerant in a closed system. This article describes and illustrates the basics of the refrigeration cycle.
