Auto-Zone Control Systems Auto-Zone Plus Systems Installation & Operation (Version 03A) - Manual (Page 19)

Auto-Zone Plus Section 1
Design Guide 1-15
Design Guide
There are seven basic steps to designing an Auto-Zone Plus system:
1. Zoning
2. Sizing the Central Unit
3. Duct Design Considerations
4. Room Air Motion / Diffuser Selection
5. Bypass Damper Sizing
6. VFD
Considerations
7. Sizing Zone Dampers
Step #1 - Zoning
Determine the number of zones. A single air handler unit can have no more than sixteen
zones. If the number of zones exceeds sixteen then more than one Zone Manager will be
required.
The primary precaution to be taken in applying the Auto-Zone Plus System is to select the
zoning so that no zone will be at maximum (design) heating (or cooling) load when any
other zone requires the opposite temperature air to satisfy its load. For example,
depending on the wall, ceiling and floor material and location within the building (e.g.
top or middle floor), a typical floor of a building usually has a minimum of nine distinct
temperature or control zones that are affected uniquely by the outdoor load. These zones
are depicted in Figure 1-3 & Figure 1-4.
Depending on the size of the building and partition layout, some of these zones may
overlap or be insignificant from a zoning standpoint. For example, Zone 9 could be
multiple conference or computer rooms where additional zoning would be required, or it
could be as small as a corridor where no zoning is required. Similarly, zones 7 and 8
could have no external windows and no partitions between them and could be considered
a single zone. Zone 6 could be divided into multiple offices with full partitions between
them, thus requiring separate Zone Controllers because of different internal loads, but the
same external load.
Generally speaking, the greater the number of individual Zone Controllers, the greater the
comfort. The designer will have to look at the specific building, balancing the costs of
multiple zones with the added comfort and energy savings possible with multiple zones,
to match the building owner's requirements.