Industrial Chiller Low Pressure Alarm Troubleshooting

What problems can be caused by low-pressure failure of a chiller?

1. Increased energy consumption

If the compressor is running at low pressure, the motor load will become smaller and a chiller with a low-pressure fault will waste power for nothing under the same cooling conditions.

2. Smaller cooling capacity

If the chiller suction pressure is low and the return air volume is reduced, the cooling capacity can not reach the target.

What are the causes of low pressure in chillers? How to solve it?

1. Insufficient Refrigerant or Leakage

Insufficient refrigerant will lead to pressure malfunction in the system, resulting in lower suction pressure. The chiller will sound a low-pressure alarm and the unit will stop.
The part of refrigerant leakage can be diagnosed from the piping connection of accessories such as compressor, condenser, filter, expansion valve and evaporator. After troubleshooting, the problem can be solved by charging the right amount of refrigerant.

2. Low Ambient Temperature

When the outside temperature is low, the cooling water and compressor oil temperature will also be relatively low. If the chiller is started at this time, a low-pressure fault alarm will be issued.
Solution: If the cooling water temperature is too low, close the cooling tower fan or throttle the cooling water to raise the cooling water temperature. If the compressor oil temperature is too low, extend the chiller preheating time, and the chilled oil temperature will raise back to normal.

3. System Pipeline Blockage

It is inevitable that impurities will seep into the system when the chiller is assembled, and after using it for a long time, various impurities will also enter the system. When there are too many impurities, the filter will be clogged, the refrigerant passage and return air will be reduced, and a low-pressure fault will occur.
Solution:Clean the filter, condenser, and evaporator.
water-cooled condenser scale

4. Expansion Valve Opening Too Small or Damaged

Expansion valve is a refrigeration system throttling device. Too small an expansion valve opening will allow less refrigerant vapor to pass through. Too little refrigeration steam will make the compressor inlet pressure low, resulting in a low-pressure fault.
Solution:Increase the expansion valve opening appropriately, or replace the damaged expansion valve.
expansion valve

5. Relay failure, Electrical System False Alarm

The relay plays the role of indirect protection equipment, compressor normal suction pressure is generally 0.4 ~ 0. 6MPa, when the suction pressure is lower than 0. 2MPa, it will lead to low-pressure protection relay action, the chiller will stop running. And sometimes the low-pressure relay will work out of order due to moisture, broken circuits, and other faults.
Solution:Check the low-pressure relay and repair or replace it. Non-technical personnel can contact the manufacturer for assistance in solving the problem.
Relay failure
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