What is indicated by excessive running of the purge unit on a low pressure chiller?

Excessive running of the purge unit on a low pressure chiller is a strong indicator that the chiller system is experiencing a refrigerant leak. The purge unit’s primary function is to remove non-condensable gases and prevent them from accumulating within the system, which can affect the overall performance and efficiency of the chiller.

When there is a refrigerant leak, the system tries to maintain the required pressure and refrigerant levels. As a result, the purge unit operates more frequently and for longer durations to compensate for the lost refrigerant and to remove air or other gases that may have entered the system through the leak. This increased activity of the purge unit signifies that the system is struggling to maintain its proper operating conditions, which is not typical of a well-functioning chiller.

A well-functioning chiller will not require the purge unit to run excessively, as it should maintain stable refrigerant levels and pressures without allowing excess air or non-condensables into the system. Instead, it would operate smoothly with minimal need for purging. Therefore, the excessive running of the purge unit directly points to an underlying issue of a refrigerant leak, making this the correct interpretation of the condition observed.