Evaporator Water Flow Too Low CGAM

Issue:

Evaporator Water Flow Too Low

• This diagnostic occurs when the difference between the "Entering Water Temperature" and the "Leaving Water Temperature" (Delta T) is larger than expected for the number of compressors running.

• The design Delta T programmed in the chiller is expected to be achieved when all compressors of the chiller are running. If less than all compressors are running and the design Delta T is achieved, this can trigger the alarm.

Resolution:    

• Validate accuracy of the entering AND leaving water temperature sensors.  Should be +/- 1 °F.
• Using Techview (KestrelView) check the "Design Delta Temperature" programmed in Unit View.  The default setting from factory is 10°F.
• This setting should be set based off the design conditions that the chiller was selected to run. This information can be found from the unit submittal, model number lookup (MNL) or pulled from the sales order.
• Use HUB solution DOC-107808:  "Compressor Short Cycling" to set design delta T based on actual conditions.  See link below.
• Check water flow pressure drop through the evaporator. Check pressure drop using stainless steel valve downstream of the water strainer (just in case there is a restriction) and the stainless steel valve on the leaving water pipe. Compare this pressure drop with design. If there is lower than design pressure drop, investigate what on the system side can cause this discrepancy.  Check strainers and valves on the system piping.

Products Affected:

• CGAM

Facts:

NOTES:     Solution to help set up design delta T, click here

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.