Auto-Zone Control Systems Auto-Zone Basic Systems Installation & Operation (Version 02C) - Manual (Page 19)

Auto-Zone Basic Section 1
Design Guide 1-13
Step #6 – Sizing Zone Dampers
Use a load program to determine the peak load for each zone. These calculations will be
used in selecting the appropriate zone damper sizes.
A round damper or rectangular damper can be selected depending on the building or job
requirements. If the job requires pressure independent damper control, the damper
selected must be a round damper. Rectangular dampers are not available for pressure
independent control. Please see Table: 1-1 for round damper selection. Please see Table:
1-2 for rectangular damper selection.
Using the maximum acceptable velocity for a branch duct (typically 1000-1500 FPM for
minimal noise), find the smallest damper that will deliver the required CFM as
determined by the load program.
Go to either the Round Damper Selection table (Table: 1-1) or the Rectangular Damper
Selection table (Table: 1-2) depending on your requirements to select the dampers.
Locate the branch velocity used in the duct design program on the left hand column of
either damper sizing chart (Table: 1-1 or Table: 1-2). Move across the chart and find the
damper which will provide the acceptable CFM to meet each zone’s airflow
requirements.
Note: Compare the damper size selected against the duct size to determine if the
next size up or down will provide acceptable performance without requiring a
transition fitting.
Up to two additional dampers may be slaved together for larger zones. See zone wiring
diagram for details. This should be reserved for situations when it is not practical to use a
single large damper.