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How to solve chiller's high pressure fault?

How to solve chiller's high pressure fault?

  • 2021-03-16

High pressure fault of chiller

The chiller consists of four main components: compressor, evaporator, condenser and expansion valve, thus achieving the cooling and heating effect of the unit.


High pressure fault of chiller refers to the high exhaust pressure of compressor, which causes the high voltage protection relay to work.The exhaust pressure of the compressor reflects the condensation pressure. The normal value should be 1.4~1.8MPa, and the protection value should not exceed 2.0MPa.Because the long-term pressure is too high, will lead to compressor running current is too large, easy to burn the motor, resulting in compressor damage.



What are the main causes of high pressure fault?


1.Excessive refrigerant charging.This situation generally occurs after maintenance, performance for suction and exhaust pressure, balance pressure are on the high side, the compressor running current is also on the high side.


Solution: Discharge refrigerant according to suction and exhaust pressure and balance pressure at rated working conditions until normal.


2.Cooling water temperature is too high, condensation effect is bad.The rated operating condition of cooling water required by the chiller is 30~35℃. High water temperature and poor heat dissipation inevitably lead to high condensation pressure. This phenomenon often happens in high temperature season.


Solution: The cause of high water temperature may be the cooling tower failure, such as the fan is not open or even reverse, the performance of cooling water temperature is high, and rapid rise;The external temperature is high, the waterway is short, the amount of circulating water is small. the cooling water temperature is generally maintained at a higher level. Additional reservoirs could be adopted.


3.The cooling water flow is insufficient to reach the rated water flow.The main performance is that the water pressure difference in and out of the unit becomes smaller (compared with the pressure difference at the beginning of the system operation), and the temperature difference becomes larger.


Solution: If the pipe filter is blocked or too fine, the water permeability is limited, the appropriate filter should be selected and the filter screen should be cleaned regularly.Or the selected pump is small and does not match the system.


4.The condenser scales or clogs.The condensed water is usually tap water, which is easy to scale when the temperature is above 30℃. In addition, as the cooling tower is open and directly exposed to the air, dust and foreign matter can easily enter the cooling water system, resulting in fouling and blocking of the condenser, small heat exchange area, low efficiency, and affecting the water flow.Its performance is the unit in and out of water pressure difference and temperature difference is large, the condenser temperature is very high, condenser liquid copper is very hot.


Solution: The unit should be back flushed regularly, chemical cleaning and descaling when necessary.


5. False alarm caused by an electrical fault.Due to high voltage protection relay is affected with damp, poor contact or damage, unit electronic board damp or damage, communication failure leads to false alarm.


Solution: This kind of false fault, often on the electronic board of the fault indicator light is not bright or slightly bright, high voltage protection relay manual reset invalid, measure the compressor running current is normal, suction and exhaust pressure is normal.


6. Refrigerant mixed with air, nitrogen and other non-condensing gas.There is air in the refrigeration system, and many times when there is a lot of air, the needle on the high pressure gauge will shake badly.


Solution: This situation generally occurs after maintenance, vacuum not thoroughly.We could empty the condenser at its highest point or re-vacuum the condenser and add the refrigerant after shut down.



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