More and more variable frequency devices (VFD)are being installed on the chilled water and hot waterpumps on the TAMU campus. Those pump speedsare varied to maintain chilled water or hot waterbuilding deferential pressure (DP) or returntemperature or flow rate at their setpoints. The chilledwater and hot water DP setpoint or returntemperature setpoint or flow rate setpoint was aconstant value or reset based on outside airtemperature. In some buildings, the chilled water andhot water DP setpoints were reset based on flow rate,but in many instances those setpoint schedules wereeither too low to maintain enough building DPrequirement or too high and consumed excess energy.The building DP reset schedule based on flow rate isstudied and compared with the other pump speedcontrol methods. Because the building DP setpointbased on flow rate method is achieved by tracking theload change, it saves energy than the other methods.In this paper its calculation procedure is generatedand the example of the building DP calculation isgiven.
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