What is the Difference between the GC2 and GC4? GC2 and GC4 Specifications.pdf 200 KB Download The GC2 allows for 2 fermenters to be connected to the glycol chiller and the GC4 allows for 4.Download PDF at the bottom of the article, for all the GC2 and GC4 tech specs. Related articles Instructions - GC2 Is the Conical Fermenter compatible with other hydrometers and thermometers? What is the maximum temperature the GC4 Glycol Chiller can be set to? Video - How to Guide on Setting Up and Using the GC4 Instructions - Original GC4