Table 1-2: Rectangular Damper Selection Data .................................................................2 0
How Auto-Zone Works
Zoning Design Guide
The Auto-Zone control system converts single-zone
constant volume rooftop packaged or split system
HVAC units into variable air volume/variable temperature multiple zone systems. The microprocessor based
Zone Manager calculates the heating and cooling requirements for each zone based on real time information received from each Zone Controller/Damper. The
Zone Manager then directs the HVAC unit to provide
the appropriate amount of heating, cooling, and ventilation to satisfy each zone’s requirements. A bypass
damper controlled, by a static air pressure sensor, modulates a bypass damper to maintain constant duct pressure.
The Auto-Zone system uses a unique 3 tier approach to
controlling the system:
•Voting Zones
•System Demand
•Priority
This 3 tier system works in an integrated fashion to
maintain proper control of the equipment and effective
control of comfort in the zone.
First the zone must initiate a vote to the HVAC unit.
This occurs when a zone becomes more than 1 degree
off setpoint. At this time a vote is placed for heating or
cooling. Next the controller evaluates the total cooling
demand or heating demand within the entire building
to see which requirement is more critical. Finally, the
system looks for any priority conditions, which would
take precedence over other zones. All three of these
elements working together provide accurate and stable
control of comfort.
Additional control features are taken into account to
provide a very effective control of the system. Some of
these include priority override, supply air temperature
limits, outside air temperature lockouts, and min./max.
control over damper position.
Substantial savings can be realized using the Auto-Zone
Zoning system instead of having to install multiple rooftop units to accommodate multiple zone requirements.
The Auto-Zone Zoning system is versatile and can be
used with any packaged roof top unit or split system. It
controls a variety of terminal unit functions including
single duct pressure dependent, pressure independent,
series fan and parallel fan terminals.
CONNECT TO OTHER
ZONE MANAGERS
120/9 VAC
TRANSFORMER
AVOID
DIRECT
SUNLIGHT
NETWORK COMM LOOP
AC LINE
VOLTAGE
COMPUTER
(OPTIONAL)
RemoteLink
CONTROLS
REMOTE LINK
(OPTIONAL MODEM)
2 CONDUCTOR
24 GA.
OUTSIDE AIR
SENSOR
24 VAC
GROUND
COMMLINKII
CONTROLS
COMM LINK II
INTERFACE
( OPTIONAL )
CONTROL CABLE
SUPPLY AIR
TEMPERATURE
SENSOR
2 CONDUCTOR
ZONE MANAGER
LOCAL COMM LOOP
120/24 VAC
TRANSFORMER
24 GA.
SYSTEM MANAGER
FAN
0
1
4
7
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MIXED
T
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OUTSIDE AIR
EXHAUST AIR
RETURN AIR
MODULATING
3 CONDUCTOR
24 GA.
LO
BYPASS DAMPER
STATIC PRESSURE SENSOR
& PICKUP TUBE
HI
2 CONDUCTOR
24 GA.
RETURN AIR SENSOR
CONNECT TO OTHER
ZONE CONTROLLERS
OR CV UNITS
SUPPLY AIR DUCT
MODULATING
DAMPER
ZONE
CONTROLLER
V
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ZONE 1
TEMPERATURE SENSOR
MODULATING
DAMPER
ZONE
CONTROLLER
WARMER
NORMAL
COOLER
OVR
ZONE 2
TEMPERATURE SENSOR
W/OVERRIDE AND SETPOINT ADJUST
UP TO 16 ZONES
Figure 1-1: Auto-Zone Plus System Overview
Auto-Zone Systems5
Zoning Design Guide
Why Should I Use Auto-Zone?
Auto-Zone is a proven system with a long history of
successful installations. Our systems have been refined
over the years with the help of feedback from people in
the field who work and live with these systems on a
daily basis. Our success is greatly due to the fact that
we have implemented changes and enhancements based
on real world experience not from tinkering with equipment in an isolated lab environment. This real world
approach provides engineers, contractors, and end users with a zone control system that is efficient, reliable,
and most importantly, keeps the customers comfortable!
What Is Unique About Auto-Zone?
Auto-Zone is unique because it has many features not
found on other systems. These features include
Non-Proprietary Design
Auto-Zone will work on any manufacturers HVAC
equipment that will accept a standard thermostat connection. This protects the end user from being locked in
to one source for service and support. In addition, AutoZone Systems include very comprehensive documentation, which was written in a format specifically for a
“non-controls technician”. Because the manuals are so
user friendly, it prevents the end user from being
“locked-in” to one contractor for service. Any new contractor needs only a copy of the system manual to have
as much technical information as any previous contractor.
Pre-Engineered Software
System design, software, and documentation has already
been done for you. This eliminates the costly expense
usually associated with conventional DDC systems,
making the Auto-Zone system more competitive and
easier to install and operate.
One System for Zoned or Single Zone
Systems
Not only does Auto-Zone provide a networked zone
control system for one or multiple zoned HVAC units,
you can also connect individual single zone units to the
system eliminating the need to use programmable thermostats.
Easy to Configure
Since Auto-Zone components are grouped into packages, configuring a system has been simplified. This
reduces the chance of ordering errors and makes system layout effortless!
User Friendly Set Up
Since the Auto-Zone comes with menu driven, fill in
the blank programming, system setup is simple. The
system manual takes you step by step through the set
up process. Default parameter values are programmed
into permanent memory so the system can be operational at start-up. Specialized training is not required.
6Auto-Zone Systems
Zoning Design Guide
True Network Communications
The Auto-Zone uses a three wire, RS-485 loop for communication between all controllers in the system. This
provides a very reliable form of communication with
flexibility of installation. The loop can be wired in a
“daisy chain” or “star” configuration. Many other zoning systems utilize “home run” wiring that requires all
communication cables to be brought back to a central
point adding additional cost to the project and complicating wiring.
High Integrity Communications
Many communicating control systems are susceptible
to electrical interference. One major manufacturer of
zoning systems recommends that their communication
cable should not be strapped to conduit because of potential interference. The Auto-Zone Systems have a
communication bus that is almost immune to any noise
problems that may be found in most commercial facilities.
Microprocessor Controllers
All controllers in the Auto-Zone have an on board
microprocessor. This is what gives the Auto-Zone its
powerful features and capabilities not found in other
systems.
Stand Alone Systems
All Auto-Zone Systems are true stand-alone and do not
require a computer to operate. Unit controllers maintain their own 7 day time clock, 365 day holiday scheduling, and setpoints within each controller.
Menu Driven Operators’ Interface
All Auto-Zone systems have an operators’ keypad and
display terminal. This gives you access to system status and parameter values without the need for a computer. The 4 line by 20 character display is backlighted
making it easy to read even in low light environments.
Menu driven programming makes the system extremely
user friendly. In addition, the interface panel is password protected to keep unauthorized users from accessing the system.
Communications Via Optional Modem
The Remote Link is used for achieving remote communications with the Auto-Zone system. It connects to the
CommLink II communications interface and a local
phone line. With the Remote Link, the Auto-Zone system can be monitored and controlled from a remote location, using a computer and the ZoneView AZ or Plus
software packages.
Memory Backup
Instead of batteries, which have to be replaced, AutoZone utilizes super capacitors to provide power for
memory backup during power outages. The major advantages to this approach is that super capacitors are
more reliable than batteries and they recharge in a matter of seconds instead of hours. T ypical memory backup
is good for a minimum of 10 days.
Modulating, Heavy Duty Actuators with
Real Time Feedback
All Auto-Zone actuators utilize true modulating control unlike many systems, which are two position. This
gives the system-improved control, which translates, to
better comfort levels. Our actuators are also rated for
2-½ million cycles, making our actuators some of the
most reliable in the industry. One other critical feature
is the real time feedback. Many other systems have no
feedback at all. They blindly estimate the travel time of
their actuator, which, in the real world, is not a very
repeatable estimate. To help correct the problems inherent with this approach, they recycle all the actuators
in the system once or twice a day . They may save a few
dollars by not including feedback but they sacrifice system performance. Not so with Auto-Zone.
Commercial Grade – Insulated Round
Zone Dampers
Auto-Zone only uses commercial grade zone dampers,
not cheap, flimsy, “light commercial” or “residential”
style dampers like many other manufacturers. Our round
damper is ARI certified and comes from the factory
fully insulated. Why? When many zone dampers are
installed they are improperly insulated or not insulated
at all. This can cause problems with the damper “sweating” from condensation. With factory insulated zone
dampers, we eliminate a common problem for the contractor while insuring the end user will not have problems with condensation dripping down onto the ceiling.
Auto-Zone Systems7
Zoning Design Guide
What Is Unique About Auto-Zone?
Rectangular Dampers
Auto-Zone uses only top of the line, aluminum air foil
rectangular control dampers. No other zone system on
the market today utilizes a damper of this quality and
performance!
Patented Flush Mount Room Sensors
Our flush mount room sensors are so unique, they are
patented (U.S. Patent No. 4,659,236). Even though part
of the sensor is recessed into the wall to provide an
attractive yet tamper proof flush mounting, internal wall
temperatures do not influence the sensor. A special plate
on the face of the sensor accurately senses space temperature. Even though the attractive off white plastic
housing is a preferred color, the sensor housing can be
painted or wallpapered to blend with room decor without affecting sensor performance. The sensors are offered in four different configurations:
• Sensor
• Sensor w/override
hundreds. ZoneView is not copy protected so it can be
installed on multiple PC’s’ without additional expense.
Just some of its many features include but are not limited to:
•Pre-designed status screens for all controllers
•Alarm dial out capability
•Programming of all system parameters
•Trend logging to Excel™ spreadsheets
•Alarm Handling
•Custom graphics capability
• Sensor w/setpoint adjustment
• Sensor w/setpoint adjustment & override
Modular Connections
Many Auto-Zone auxiliary devices are connected to the
controllers via modular plugs like the ones used on telephones. This simplifies installation and eliminates the
possibility of wiring errors. The devices, which utilize
this method, are damper actuators for zone and bypass
control, auxiliary relay boards, and static pressure/air
flow sensors. There is one interesting side note about
the auxiliary relay board and airflow sensors. These
devices are typically used on the zone controllers in the
Auto-Zone Basic & Plus systems. When the system is
powered up, it automatically looks to see if these devices are connected to the controller. If they are, the
controller automatically reconfigures itself to utilize
these devices and activates the appropriate set up screens
back at the operators interface. Pretty neat don’t you
think!
FREE! Windows™ Graphics Software
Each Auto-Zone system can be monitored on site or
remotely using a PC and our ZoneView Plus™ Windows 98 software. This full-featured package is very
user friendly and can be used to monitor one system or
Open Protocol System
Auto-Zone is an open protocol based system allowing
other manufacturers to develop direct interfaces to the
communications loop. This gives you the ability to integrate the Auto-Zone system into products from other
vendors. Our engineering staff will be glad to assist any
vendor in this process.
8Auto-Zone Systems
Zoning Design Guide
Zoning Systems Versus True VAV Systems
General
Even though there are some similarities between zone
control systems and Variable Air Volume (VAV) systems, there are some major differences. In many cases
systems will be called VAV when in fact they are really
a zoning system or are referred to as a zoning system
when they are really a VAV system. Always make sure
that you do not try to adapt a zoning system to a VAV
design system. Understanding the differences will help
you to prevent misapplication of the Auto-Zone zoning
system. In the paragraphs that follow we will try to explain the differences, advantages and disadvantages of
each and explain their operation.
V AV Systems
These systems consist of an HVAC unit that is generally a cooling only unit and VAV terminal units located
in the downstream ductwork that are used to control
the amount of constant temperature air delivered to the
various building zones. Sometimes the HV AC unit may
have gas or electric heat, but it is typically sized and
applied for morning warm-up purposes. The HV AC unit
is designed to vary the volume of air that is supplied to
the duct system by using either inlet vanes or an electronic variable frequency drive. These devices modulate to control the air flow through the supply fan in
response to the static pressure in the duct system. VAV
systems typically use high velocity VAV terminal units
to distribute the air to the zones. As the various VAV
terminal units in the different zones open and close to
supply the constant temperature air to the spaces, the
HVAC unit varies the volume of constant temperature
air based on the static pressure in the ductwork. The
HV AC unit is designed to maintain a constant cold supply air temperature regardless of the air flow volume in
the system. The HVAC unit cycles it’s cooling stages
to maintain a constant predetermined supply air temperature. It typically runs continuously based on a schedule. For perimeter zones requiring heat, reheat coils
(electric or hot water) located in the terminal units are
used to supply heated air to the space. Many times fan
powered terminal boxes are used and in many cases
also incorporate electric or hot water heating coils to
provide perimeter zone heating. In summary a true V AV
system uses a variable volume fan supplying constant
temperature air to the system with variable volume terminal units used to control the volume of constant temperature air delivered to the space. Generally these systems use pressure independent damper control.
Auto Zone Systems
The Auto-Zone zoning system is completely different
in operation and design from the VAV system previously discussed. One of the major differences between
the zoning system and a true VAV system is that the
HVAC unit used on a zoning system utilizes a constant
volume fan. Air volume control of the zoning system is
achieved by bypassing air from the HVAC unit supply
duct back into the HVAC unit return air duct on the unit
inlet. This bypass air is controlled based on a static pressure sensor located in the supply air duct downstream
of the unit supply air discharge. The bypass damper
modulates open and closed based on the static pressure
in the duct. The temperature at the HV AC unit dischar ge
varies in relation to the demand from the zones. Typically the HVAC units used for the zoning system will
have both heating and cooling capabilities. The fan supplies a constant volume of cold or hot air to the duct
system and which is fed to the individual zones by modulating zone dampers. Each zone controller relays its heating or cooling demand to the HVAC unit controller. The
HVAC unit controller determines its mode of operation
(heating, cooling or vent mode) depending on the demand from the zone controllers. The unit controller utilizes a voting system to determine the correct mode of
operation. Each zone controller determines (based on
its heating and cooling setpoints) whether or not to use
the air being supplied by the HVAC unit. For example,
one of the zones is calling for cooling when the temperature in the duct is above the zones cooling setpoint.
This zone will move to its minimum cooling position
to prevent warm air being introduced into the space.
With the zoning system the zone dampers are generally
pressure dependent. Pressure independent operation is
available but is not very common. Reheat and/or fan
powered terminal units can be used but aren’t commonly
part of the typical zoning system.
Conclusion
In many cases VAV systems go over budget because of
the increased cost of a VAV, HVAC unit and the expensive VAV controls associated with the system. Many
times the system can be redesigned to a zoning system
using Auto-Zone controls with a significant cost savings and equal or better performance and comfort than
the VAV system would provide. Be sure to follow the
instructions in this design guide for your zoning system.
Auto-Zone Systems9
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