One of the basic components selected when installing a walk-in cooler/freezer or any field-assembled refrigeration system is the metering device, typically the thermostatic expansion valve (TXV). The TXV needs to be selected to match the Btu capacity of the system’s evaporator and compressor.
A well-designed medium temperature refrigeration system will maintain both a proper case temperature and relative humidity (rh). The preservation of food depends not only on the temperature, but also on the relative humidity within a case.
Contractors do not like to hear the word “callback.” They cost money and degrade a customer’s respect for and opinion of the service contractor. So how can a technician reduce the number of times he must revisit a repair?
While troubleshooting or installing refrigeration systems using a thermostatic expansion valve, it is a relatively common task to measure the superheat value of the refrigerant leaving the evaporator. However, there is a major consideration when using this measurement to analyze the operation of a system.
In many aspects the first part of a job is like detective work — not only does a technician need to identify the problem but he also must determine its root cause. A good initial step is to visually inspect the entire system.
Many refrigeration systems are installed using an outdoor air-cooled condenser. When these systems are installed in a climate where the outdoor temperature drops below 60°F, some means of preventing the condensing pressure from dropping too low must be incorporated into its design.
Replacing a compressor is neither simple for a technician nor inexpensive for the customer. Before replacing a compressor, a technician needs to ensure that it is truly defective. Unfortunately, sometimes good compressors get replaced as a result of a misdiagnosed problem.
When a refrigeration system fails, many times the cause can easily be diagnosed. However there are occasions when the cause cannot easily be determined - either the true cause is unclear or the technician is unsure of a problem. How do you work through these jobs? One method used by some techs is to “read and record.”