Steps for balancing procedure for pressure controlled DCV systems!
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January 27, 2015

Steps for balancing procedure for pressure controlled DCV systems!

Balancing of a pressure controlled DCV system consists of the following steps:

  • Control that all the DCV units have supply voltage and no polarity error
  • Control that the pressure sensor is mounted on a location with stable static pressure or uniform velocity profile, by performing measurements over the duct cross section with a Pitot-tube or a hot-wire anemometer.
  • Select a pressure set point which is slightly higher than necessary. This can be deduced from pressure drop calculations, or empirically.
  • Program the actual maximum and minimum airflow rate values (Vmax and Vmin) on each DCV damper and set the dampers to automatic mode. Control that all the DCV dampers get the maximum airflow rate, and read the opening rate. Find the index damper, which is the damper with the highest opening rate.
  • Adjust the pressure set point until the index DCV damper gets the maximum airflow rate without throttling (about 80 % opening rate). You have then found the energy optimal pressure set point, which is the lowest pressure set point which provides the right airflow rates according to the designed values.
  • Complete the VAV control form. The completed control form should be included in the documentation of the ventilation system.

PC-DCV

Source from article on “Commissioning for energy-optimal Demand-Controlled Ventilation” by Mads Mysen, Peter G Schild, Axel Cablé and John Woollett