The MP-Bus enables the damper position of the VAV controller in each zone to be monitored. The damper that is open the widest serves as a reference. The speed of the fan is reduced until this damper is about 85% open and other dampers are closed as required in response to lower airflow requirements.
Since air volume is proportional to the speed of the fan and static pressure is proportional to the square of the fan speed, potential savings are immediately apparent. In addition, fan power consumption is proportional to the cube of the fan speed.
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