This option changes the default upper optimal percent load to 80% and the lower optimal percent load to 40%.
When Variable Speed chillers are controlled by Building Load, the Upper and Lower Optimal Percent Load points are dynamically reset based on chiller lift to minimize total chiller power consumption. The lift is defined as the difference between the condenser water temperature entering the chiller and the CHW Supply Temperature Setpoint. The application resets the Upper and Lower Optimal Percent Load points within a user-defined range (default = 30–40% and 65–80% for the Lower and Upper points, respectively) and over a user-defined range of lift (default = 26–41°F).
These range values are defined in the Chiller Optimal Percent Load Setpoint Reset module. The reset Upper and Lower Percent Load points are passed from the Chiller Optimal Percent Load Setpoint Reset module to the Chiller Selector module. The module uses a time period (default = 5 minutes) to determine how often the inputs are evaluated and the calculation executed.