Issue:
Overshooting Chilled Water Setpoint
Resolution:
The microprocessor starts and stops compressors based on chilled water demand. Compressors are commanded off based on a Differential To Stop setpoint. This is factory set at 2 degrees and is not field adjustable.
This means that a compressor will continue to run until the Evaporator Leaving Water Temperature (ELWT) sensor is 2 degrees F below the Chilled Water Temperature Setpoint. (CWS)
Note: It is not unusual to see the chilled water temperature even more than 2 degrees F below the CWS. The microprocessor initiates the shutdown once the ELWT is 2 degrees F below CWS, but the temperature may continue to drop until the compressor actually stops. The amount of drop will be influenced by load changes, water flow, etc.
Notes:
Changes:
Other Question/Problem/Cause Statements:
- Overshooting Chilled Water Setpoint
Facts:
- RTAA 130-400 Ton (Pueblo)
- RTAA 70-125 Ton (Pueblo)
- RTUA
- RTWA
Original wave: case2514
Document Identifier: DOC-74870
Document Identifier: 74870
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.