Issue:
What can cause low pressure control diagnostic?
Resolution:
Use of an ethylene glycol-type antifreeze reduces unit cooling capacity; this condition must be accounted for during total system design. Also the low pressure control may need to be changed. Contact the local Trane representative.
CGAF Tuning Parameters:
- The Control Response Setpoint can be increased to make the controls more responsive. (Default 25)
- Decreased makes the Control Response less responsive
Application:
- Changing from Comfort Cooling to Process Cooling can aid in short loop applications. However, compressors will cycle more.
- If compressor operation is interrupted by a loss of power or by a manual reset diagnostic, a minimum of one minute must elapse before the affected compressor(s) will be allowed to restart for "Process" applications. A minimum of three minutes must elapse before the affected compressor(s) will be allowed to restart for "Comfort Cooling" applications.
Glycol:
- If the chiller has glycol, and the Chilled Water Setpoint (CWS) is above 40F; the LPC controls need to be changed to either a 25 or 20 psi switch.
- If the chiller does not have glycol, the 45psi default switch is required.
Use of an ethylene glycol-type antifreeze reduces unit cooling capacity; this condition must be accounted for during total system design. Also the low pressure control may need to be changed. Contact the local Trane representative.
Notes:
Trane sales can run a product selection (TOPPS) to match chiller to application should be run to determine which switch to use. From output view convert the saturated suction temperature to pressure to determine which switch (25/40 psig or 20/35 psig) to use.
Tripping may occur occasionally on both circuits; mainly in cooler weather.
Changes:
Other Question/Problem/Cause Statements:
- Can the Low Pressure Cutout trip time be altered?
- Low Pressure Cutout?
- Low Pressure Control?
- LPC?
-
Compressors are all shutting off on freeze protection (LPC).
- Chiller is tripping on low pressure on both circuits.
- Can a lower pressure LPC be installed safely?
- Running less than 40F degree leaving water temperature with no glycol in water.
Facts:
- Air-Cooled Chiller - Intellipak (CGAC, CGAF)
- 45 psig Low Pressure Switches installed.
- INTELLIPAK CHILLER 20-60
Document Identifier: DOC-82825
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.