Issue:
Fan staging logic
Resolution:
RTUA/RTCA 70-125, RTAA 70-125 TON Chillers:
Input from the outside air temperature sensor, the saturated condenser temperature sensor and the saturated evaporator sensor are monitored for staging. Prior to the compressor starting, the outside sensor is reviewed. If the ambient temperature is less than 55 F only the lead fan should start. Above 55 F additional fans will stage prior to compressor starting. The warmer the ambient the more fans will stage.
After the compressor starts, the micro will convert the saturated condenser temperature and saturated evaporator temperature to pressure. During normal operation, the micro uses PID control to maintain a 70+/-5 psid between the condensing pressure and the evaporator pressure.
Notes:
Changes:
Other Question/Problem/Cause Statements:
- Fan staging logic
- VFD Fan staging
- Head pressure control
Facts:
- Air-Cooled Chiller (Pueblo) (RTAA 70-125 Ton)
- Air-Cooled Condenser (Pueblo) (RTCA)
- Compressor Chiller (Pueblo) (RTUA)
Document Identifier: DOC-81713
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.