What constitutes a perfectly working refrigeration? It has the right temperature of the water, allows the perfect level of water flow along with an adequate amount of airflow across the condenser and evaporator. But often these parts of the refrigerator fail to work properly and gives rise to unwanted problems such as superheating, improper head pressure, and suction pressure and subcooling. So, we list down a few common issues that we face on a day to day basis in our refrigeration system.
Most refrigerator manufacturing companies opine that as long as the level of oil is visible in the sight glass, the oil level is fine. But there are some manufacturers that specify that the level of oil must be between one-third and two-thirds of the sight glass. However, most manufacturers agree on the point that the level of oil should never rise above the sight glass. Therefore, you should always refer to the specific recommendations of oil level and use the specified type of oil only.
High oil level- This generally occurs when new oil is added even when it is not needed. When the system is in running condition, some amount of oil leaves the compressor along with the refrigerant and traverses into the system. If the velocity is at a low speed, or in case there is no or improper oil traps, the oil will not be able to run in its due course. If this the case, you will be compelled to add more oil. But before you do so, it is imperative that you check whether there is any leakage and when there is no leakage, it means that the oil is in the system. When there is too much oil in the system, it may lead to any of these conditions:
- The evaporator becomes clogged with oil which, in turn, reduces the heat-absorbing capacity of the evaporator by making a layer inside the piping.
- The compressor attempts to compress the liquid oil which damaged the valve.
- In case the oil level is too high, the crankshaft hits the oil every time it turns and leads to a rise in compressor amperage. When it is repeated for a long span of time, it may cause damage to the wrist pin and crankshaft.
Low oil level- When there is oil leakage or when the oil is not cycled back at an optimum level, it causes a disruption in the refrigeration system owing to low oil pressure. When the oil leaves the compressor but gets stuck at places within the system, it could lead to building up of oil slugs within the compressor, therefore, causing damage.
Oil traps are useful in aiding the reversal of proper oil level to the compressor. They are generally found in vertical riser refrigerator beginning at the bottom of the riser. The oil trap is devised for collecting oil and then it builds up in the oil trap, leaving a very small space in which the refrigerant can flow. With the rise in velocity, it gradually comes back to the compressor so as to it will not clog the system with an overflow of oil. This problem can be solved by installing an oil separator.
In case you find that there is oil leakage, it must be fixed and the right amount of oil be added to the system. As most of the hermetic compressor does not have any sight glass, the sound of metal striking metal is proved evidence that there is a low oil level.
Presence of noncondensable:
Being overcharged by refrigerants or the presence of noncondensable can lead to a number of vital system issues. In order to detect whether the problem is caused by noncondensable, you can shut off the unit and give enough time in between for reaching the right temperature. Following this, you should check the discharge pressure if it is within 5psig of the pressure at that particular temperature. In case the pressure is high, there is surely a presence of noncondensable. In such cases, you might have to replace the liquid to find the filter. You should never delay repair or replacement of these parts as it might significantly reduce the life of your compressor and you might incur high energy costs.
There are a lot of issues that might affect the amperage drawn by the compressor. For instance, if there are noncondensable within the system, the compressor is forced to work harder causing high amperage. On the other hand, overheating and loose wire connections might also draw high amperage. If you are in charge of its maintenance, you should consult an expert electrical contractor for making the necessary repairs in the system.
In the last few years, the difference in frequency drives along with numerous speed motors have become the common ingredient. The easy availability of variable frequency drives, variable air volume, adjustable speed drives, and inlet guide vanes allow the airflow to constantly alter. The pressure of the refrigeration change with these and it might be affected by several issues such as dirty evaporator coil or filter, improper speed of can, torn of the loose belt, closed return or supply diffuser or improperly installed pipework in new construction.
Most refrigerator manufacturers suggest that the airflow should be kept to 400 CFM for each ton throughout the evaporator coils. When it is not possible to achieve these levels, it will hamper the proper working of the system.
It is very important to maintain the airflow because when the airflow is reduced, it can surge head pressure while reducing the overall capacity of the system.
Therefore, no matter whether you are a refrigerator technician or not, it is imperative that you are at least capable of asking the right questions. This will help in troubleshooting a system for maintaining the right building operations so that you can easily keep up healthy tenant relations.