Issue:
CGAF Fan Staging and fan staging improvement for Shell and Tube models (pre-April 2003)
Resolution:
CGAF
Newer CGAF chillers have a plate and frame heat exchanger. With that design, they also have a newer and improved fan staging algorithm that can effectively improve the low temperature performance of older shell and tube chillers.
If plate and frame CGM and MCM modules are installed in a low ambient shell and tube CGAF chiller, it is important to note that the newer MCM module has an additional fan output. When installing this module and doing the subsequent wiring, careful attention must me made to reconnect the fans to the correct terminals on the new module.
The older MCM (or dual SCM) do NOT feature a "Low Ambient Fan Output" but the newer Modules do. When installing this module, it will be required to move the Cond Fan "A" wiring (P12-5,7 first fan contactor, old MCM) to the Low Ambient Cond Fan #1 output connections on the new MCM (J26-5,7). Once those have been made, the Cond Fan "B" (P12-1,3) connections can stay in their current location and will now be called Cond Fan "1A" on the newly installed MCM module. On a 60 ton chiller, there are 3 fans and if desired, a 3rd fan contactor can be added and wired to the Cond Fan "1B" output on the newly installed MCM for even better fan staging and control. This will allow all the fans to be independently controlled for more reliable head pressure control in wider ambient temperature conditions.
This same procedure can be applied to the "B" Circuit on 40, 50 and 60 Ton chillers.
Notes:
Changes:
Other Question/Problem/Cause Statements:
- How can I improve my CGAF fan staging?
- Can I improve my fan staging by adding a new CGM and new MCM?
- Can I use the new CGM and MCM modules found on plate and frame chillers on my shell and tube chiller?
- CGAF fan staging
- Fan staging upgrade
- adding a fan contactor to the CGAF
Facts:
- CGAF
- Air-Cooled Chiller - Intellipak (CGAF)
Document Identifier: DOC-93740
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.