Which tonnage should be used when using refrigerant calculator while considering a chiller plant serving a static ice thermal storage system? When chillers are in Ice Making Mode producing 24F fluid; chiller capacity is substantially reduced as compared to Chiller Mode when chiller is producing 42F fluid. For example a 100 ton chiller at 42F discharge temp may produce 65 tons when producing 24F fluid. I am thinking a pro-rated calculation may be appropriate based on run hours per day or week. Your thoughts and comments please and thank you.