Bryant ZONE PERFECT PLUS ZONEBB2KIT, ZONE PERFECT PLUS ZONEBB8KIT, ZONE PERFECT PLUS ZONEBB4KIT Zoning Design Manual
zoning design guide
ZONE PERFECT PLUS
ZONEBB2KIT
ZONEBB4KIT
ZONEBB8KIT
Cancels: New AP17-2
4-98
TABLE OF CONTENTS
Page
INTRODUCTION........................................................................1
OVERVIEW OF ZONING.........................................................1
What is Zoning? .........................................................................1
Is a Zoning System Right for This Job? ...................................2
ZONE PERFECT PLUS FEATURES....................................2-3
Humidification Control...............................................................2
Dehumidification Control...........................................................2
Damper Control Scheme............................................................2
OUT Zones .................................................................................3
Bryant Access Home Zoning Software .....................................3
Eight-Zone Capacity...................................................................3
Ease of Installation and Installer Test .......................................3
ZONE PERFECT PLUS COMPONENTS............................3-4
User Interface..............................................................................3
Equipment Controller .................................................................4
Zone Sensors...............................................................................4
Remote Sensors.......................................................................4
Smart Sensors..........................................................................4
Equipment Sensors .....................................................................4
Zone Dampers.............................................................................4
DESIGNING A ZONE PERFECT PLUS
INSTALLATION ..................................................................4-10
Assigning Zones .........................................................................5
Task 1—Assess the homeowner’s goals
for comfort and energy savings...............................5
Task 2—Conduct a site survey and make
preliminary zone assignments..................................5
Conducting a Site Survey....................................................5
Making Preliminary Zone Assignments .............................5
Sizing the Equipment .................................................................6
Task 3—Calculate block load estimates
and zone load estimates...........................................6
Task 4—Size heating and cooling equipment .......................6
Task 5—Choose register and return locations.......................7
Determining the Number of Returns..................................7
Selecting Return Locations .................................................7
Selecting Register Locations...............................................7
Meeting Zoning Challenges in Two Story Homes ............7
Recording Return and Register Locations..........................7
Task 6—Determine Bypass Needs.........................................7
Task 7—Lay out supply ducts and locate dampers...............7
Task 8—Determine appropriate damper and duct sizes........8
Determining Duct Size Based on Damper Size.................8
Why Oversized Ducts are not a Problem
with Zone Perfect Plus........................................................8
Task 9—Choose locations for zone sensors..........................9
Considerations When Retrofitting an Installation .....................9
Installing the System..................................................................9
COMPONENTS REQUIRED FOR
SPECIFIC APPLICATIONS..................................................10
Thermostatic Expansion Valve ................................................10
Leaving Air Temperature Sensor.............................................10
Heat Pump Temperature Sensor ..............................................10
Outdoor Temperature Sensor ...................................................10
SPECIAL APPLICATIONS USING
ZONE PERFECT PLUS ....................................................10-12
Understanding the Requirements of Setback with Zoning .....10
Using Multi-Stage Equipment with Zoning.......................10-11
Using Variable-Speed Blowers with Zoning...........................11
Bypassing with Zoning .......................................................11-12
Bypassing to an Unconditioned Space.................................11
Bypassing to a Conditioned Space.......................................11
Bypassing Directly to the Air Return ..................................11
Bypassing Using OUT Zones...............................................12
GLOSSARY...........................................................................12-13
APPENDIX—WORKSHEETS............................................13-17
Zoning Design Checklist..........................................................14
Homeowner Survey.............................................................15-16
Floor Plan Worksheet...............................................................17
INTRODUCTION
This guide provides information to help you design a Zone Perfect
Plus installation. It discusses general topics related to designing a
residential zoning control system, as well as specific information
about Zone Perfect Plus.
Use this guide to help you design a zoning system that will:
• Meet or exceed the homeowner’s expectations regarding the
system’s capabilities. This goal will result in improved customer perception of your company, as well as repeat business
and referrals.
• Protect the heating and cooling equipment used in the system.
This goal will result in improved system reliability, longer life
of heating and cooling equipment, and reduced warranty costs.
To design a zoning system to perform well under all conditions, it
is essential to view the system as a whole at the design stage, rather
than to begin selecting and installing individual components
without a careful assessment of how they will work together. Be
sure to perform all of the tasks described in this guide before you
begin to install components.
This guide assumes that you have experience designing residential
heating and air conditioning systems. The information in this guide
is intended to supplement that experience. This guide does not
address commercial applications of Zone Perfect Plus.
OVERVIEW OF ZONING
Residential zoning systems bring the possibility of total comfort
control to the homeowner by providing exactly the right amount of
heating or cooling to each living space. Comfort can be described
as the absence of sensation. Ideally, a zoning system should keep
the occupants of the home comfortable without them being aware
of the system.
A. What is Zoning?
A zone is a conditioned space (one room or a group of rooms) that
is separately controlled by its own sensor. There are as many zones
in a home as there are sensors.
A zoning system is a heating and cooling control system that
maintains each zone of a home at a predetermined temperature and
that maintains the home at a predetermined humidity. In addition
to meeting these basic goals, Zone Perfect Plus is designed to:
—1—
• Direct conditioned air proportionately based on the needs of
each zone, so that the zone(s) with the greatest demand receive
relatively more conditioned air.
• Keep the sound produced by the system low enough that
residents will not find it objectionable.
• Conveniently interface with and protect the home’s heating and
cooling equipment.
• Maintain at least the minimum airflow necessary to keep
heating and cooling equipment running efficiently.
B. Is a Zoning System Right for This Job?
When designing a zoning system, it is important to keep in mind
what a zoning system can and cannot do. A zoning system is only
part of a complete heating and cooling system for a residence. A
home’s heating and cooling system has a limited heating and
cooling capacity. A zoning system cannot increase that capac-
ity.
A zoning system reduces the effective size of the air distribution
system as dampers are adjusted and closed to meet the needs of
zones. The primary challenge when designing a zoning system is
to make sure that the air distribution system cannot become so
effectively small that the reduction in airflow causes one of the
following problems:
• Air noise becomes excessive.
• The heating or cooling equipment is shut down because
temperature limits are exceeded.
• The life of the equipment is reduced because of stresses related
to excess temperatures.
The addition of a zoning system will not correct existing duct
problems. A zoning system will compensate for oversized ducts,
but might make a bad situation worse in the case of undersized
ducts. There are many ways to make a marginal duct system
perform better. Most of these approaches involve changing ducts,
registers, and/or heating or cooling equipment.
PLUS
ZONE PERFECT
This section briefly describes features that are new in the Zone
Perfect Plus system and that distinguish this system from both
Zone Perfect and other residential zoning systems.
Zone Perfect Plus’s innovative features include:
• Humidification control
• Dehumidification control
• Sophisticated damper control scheme
• OUT zones
• Bryant Access Home Zoning Software
• Eight-zone capacity
• Improved ease of installation and installer testing.
A. Humidification Control
If a humidifier is included in the heating and cooling system, Zone
Perfect Plus can directly control it. A solid-state humidity sensor
is built into the User Interface to monitor and control humidity in
the home. The Equipment Controller’s HUM output controls any
humidifier with a 24-vac input.
The homeowner can set a humidify set point to any value between
10 percent and 45 percent relative humidity, or can turn off the
humidify feature. When the humidity drops 2 percent below the set
point in the heating mode, the system activates the HUM output to
turn on the humidifier. When the humidity rises 2 percent above
the set point in the heating mode, the system turns off the HUM
output. Humidification is provided only in the heating mode.
If the system includes an outdoor temperature (ODT) sensor, the
installer or homeowner can select an automatic humidity level
adjustment. This selection provides a 1 percent reduction in the
FEATURES
humidify set point for every 2°F reduction in outdoor temperature.
The homeowner can change the system’s humidify set point at any
time, and the system automatically adjusts the set point in response
to the outdoor temperature. This feature helps prevent sweating of
windows in very cold weather while allowing higher humidity
levels in warmer weather.
The system can be set to provide humidification only when there
is a humidify demand and any heat output (heat pump, furnace, or
auxiliary heat) is on. Alternatively, the system can be set to turn on
the HUM output and the blower when there is a humidify demand.
This selection allows humidification when there is no heat demand.
B. Dehumidification Control
The Equipment Controller’s dehumidify output can be used to
control any 24-vac device that decreases humidity when its control
signal is removed. Zone Perfect Plus includes an extensive set of
features for enhancing and controlling dehumidification, particularly when used with a variable-speed (ICM) blower.
The homeowner can set a dehumidify set point, separate from the
humidify set point, between 50 percent and 90 percent relative
humidity, or can turn off the dehumidify feature. When the
humidity rises 2 percent above the set point in the cooling mode,
the system turns off the dehumidify output. When the humidity
falls 2 percent below the set point in the cooling mode, the system
turns on the dehumidify output, supplying 24vac. Dehumidification is provided only in the cooling mode.
Zone Perfect Plus provides the following modes of humidification
control:
• Mode 1: When an ICM blower with a dehumidify input is used
with the system, the Equipment Controller’s dehumidify output
can be connected to it. This connection provides reduced
cooling airflow while dehumidification is needed, yielding
better moisture removal from cooling air.
• Mode 2: If the system has a 2-speed compressor and a PSC
blower, a dehumidify demand makes the compressor operate at
high speed only for any cooling demand. High-speed operation
provides better water removal than low-speed operation under
these circumstances.
• Mode 3: In a standard system with a PSC blower, Zone Perfect
Plus lowers the cooling set point up to 3°F in response to
dehumidify demand. This feature increases the equipment’s run
time and lowers the evaporator coil temperature.
• Mode 4: The vacation mode optional feature provides humidity
control by operating the cooling system when cooling is not
required. If the humidity rises above the dehumidify set point,
the system executes a special dehumidification routine. As long
as zone temperatures are not less than 70°F, a dehumidify
demand turns on the cooling equipment, limiting its ON time to
no more than 7 minutes at a time.
C. Damper Control Scheme
Up to 3 dampers can be wired in parallel and connected to 1 zone
output. A multi-damper enabler is not needed.
Using the set points and temperatures for each zone within the
system. Zone Perfect Plus determines whether active heating or
cooling is required, the zoning system:
1. Fully opens 1 or more dampers and positions others so that
all zones will be conditioned back to their set points at the
same time. Based on experience, the system learns the best
damper positions for meeting the home’s current demand
for heating and cooling and starts from these positions when
it determines that heating or cooling is required.
2. Turns on the necessary heating or cooling equipment.
3. While the equipment is on, once every 2 minutes makes
small adjustments in damper positions so that all zones
converge on their set points at the same time.
—2—
4. Turns off the equipment when all zones reach their set
points.
5. Leaves dampers in their final positions while the equipment
is off.
6. If the equipment does not run for 2 hours, fully opens all
dampers.
Thus, the zoning system controls the damper(s) for each zone
based on the overall needs of the home and the relative need of the
zone. This scheme makes smooth and efficient use of the system’s
heating and cooling capacity.
When all zones require conditioning and all dampers are fully
open, there is some reduction in airflow velocity and the air
distribution system might not throw air as well as one might want.
The zoning system compensates for this reduction in airflow
velocity by partially closing dampers to zones that are improving
more quickly than others. This feature allows increased airflow
velocity in the remaining ducts, helping those zones become
conditioned more quickly than would otherwise be the case.
D. OUT Zones
Zone Perfect Plus has a new feature that lets the homeowner assign
OUT status to any zone with the touch of a button. By assigning
OUT status to a zone, the homeowner tells the system that the
selected zone is unoccupied and does not require conditioning. The
homeowner can set zones to OUT at any time, or OUT can be
programmed according to a schedule, like temperature set points
are programmed.
The system normally supplies no conditioning to an OUT zone. If
the temperature in an OUT zone exceeds 85°F or falls below 60°F,
the system supplies conditioning to maintain the zone within these
limits.
The system uses OUT zones to relieve the heating or cooling
equipment under equipment overload conditions. If the total
demand from all zones is such that the airflow is insufficient (or
bypassing is excessive), the leaving air temperature (LAT) sensor
or heat pump temperature (HPT) sensor detects this condition.
When temperatures begin to approach their limits, the system first
begins to open dampers in the OUT zones to relieve the overload
condition.
The system also monitors temperatures in the OUT zones and
never lets OUT zones become cooler than the coolest zone (in
cooling) or warmer than the warmest zone (in heating). This
feature prevents over conditioning of OUT zones while still using
them to relieve overload conditions.
Also, when a zone is set to OUT and the system is set up for
dehumidification, the OUT zone can be used to help remove
humidity by cooling it as much as possible. When there is a
dehumidify demand without a cooling demand, the system fully
opens the dampers in any zones set to OUT. The zones can be
cooled to as low as 70°F. If an OUT zone reaches 70°F, its damper
closes.
When all zones are set to OUT, the house is in vacation mode. The
cooling equipment comes on either to maintain the house below
85°F or to maintain the dehumidify set point by cooling the house
to as low as 70°F. This feature is extremely useful for unoccupied
homes in hot and damp climates.
E. Bryant Access Home Zoning Software
Bryant provides a software utility—Bryant Access Home Zoning
Software—that installers can use to assist them during a Zone
Perfect Plus installation. This software is provided free of charge
on the Zone Perfect Plus Introduction CD-ROM. It can be run
under Windows 3.1 or Windows’95 on a portable computer.
This software lets the installer:
• Monitor the zoning system during installation.
• Program the comfort schedule for the system.
• Perform additional setup tasks, if necessary.
F. Eight-Zone Capacity
Zone Perfect Plus is available in 2-zone, 4-zone, and 8-zone
models. Of course, not all zones have to be used in an installation
for the system to operate properly. For example, an 8-zone model
can be used for a system with 2 to 8 zones.
G. Ease of Installation and Installer Testing
Zone Perfect Plus has been designed to make it easy to install. For
example, connections on the Equipment Controller are color coded
to make them easy to identify.
Zone Perfect Plus provides an installer setup mode that makes it
easy to test the system during installation. By pressing buttons on
the User Interface, the installer can:
• Fully open a selected zone’s damper(s) and close all other
dampers.
• View the current temperature of any zone.
• Turn the blower on or off.
• Operate heating, cooling, or auxiliary heating for 2 minutes.
PLUS
ZONE PERFECT
COMPONENTS
The main components of a Zone Perfect Plus system are:
• A User Interface
• An Equipment Controller
• Zone sensors
• Equipment sensors
• Zone dampers
Each of these components is described in the following sections.
A. User Interface
The User Interface, show in Fig. 1, is the command center or
"brains" for the entire zoning system. Through the User Interface,
the homeowner can program the temperature and schedule requirements for each zone, and can view the actual temperatures for each
zone. The User Interface usually is located in the main living area
for convenient access.
A98337
Fig. 1—User Interface
The main function of the User Interface is to monitor signals from
the temperature sensors, determine what actions need to be taken
to maintain each zone at the temperature programmed for it, and
send the appropriate control signals to the zone dampers and the
heating or cooling equipment.
The User Interface also includes a temperature sensor, which
usually is used to monitor the temperature in its zone (Zone 1), as
well as a humidity sensor. In some cases, the need to mount the
User Interface in a location convenient for the homeowner might
make its location unsuitable for accurately sensing the zone
temperature. In such cases, a Remote Sensor can be used for the
zone instead of the User Interface’s built-in sensor.
—3—
B. Equipment Controller
Fig. 2—Equipment Controller
The Equipment Controller, shown in Fig. 2, is essentially a
junction box for connecting all of the temperature sensor inputs,
and all of the outputs to the zone dampers and to the heating and
cooling equipment. It contains circuits and relays that provide
control of the zoning system, as well as control of the heating and
cooling equipment. The Equipment Controller operates under the
control of the User Interface.
C. Zone Sensors
Zone Perfect Plus kits include Remote Sensors. Optional Smart
Sensors also are available for use with the Zone Perfect Plus
system. Each of these types of sensors is described below.
REMOTE SENSORS
Remote Sensors, shown in Fig. 3, are used to measure the
temperature in each zone. A Remote Sensor does not provide a
means to view or adjust the zone temperature; the User Interface
provides a means to view and adjust temperatures for all zones.
A98338
• Zone Perfect Plus installations must include a LAT (leaving
air temperature) sensor.
• If the installation includes a heat pump, an HPT (heat pump
temperature) sensor also must be installed.
•AnODT (outdoor temperature) sensor is optional in most
applications.
For more information about equipment sensors, see the section
"Components Required for Specific Applications."
E. Zone Dampers
Each zone must have at least 1 zone damper, shown in Fig. 4. If
more than 1 duct serves a single zone, up to 3 dampers may be
wired in parallel to a single output on the Equipment Controller.
Each zone damper is operated by an electric motor actuator, which
receives signals from the Equipment Controller. Dampers have 15
positions, ranging from fully closed to fully open. The position
selected for each damper at any given time is based on the relative
conditioning needs of each zone in the current mode.
A98339
Fig. 3—Remote Sensor
SMART SENSORS
The Smart Sensor measures and displays the temperature in the
zone. It also provides a means to adjust the temperature in that
zone only.
D. Equipment Sensors
The following equipment sensors are used in Zone Perfect Plus
installations:
—4—
A98340
Fig. 4—Zone Damper
PLUS
DESIGNING A ZONE PERFECT
INSTALLATION
The main objective when designing a zoning system is to maintain
at least the minimum airflow through the system when only 1 zone
requires conditioning, yet still provide sufficient airflow when all
zones require conditioning. The tasks described below provide
step-by-step instructions for designing an effective zoning system.
These tasks are grouped into the following phases:
N
Bath
Bath
Bedroom
Large
WIndow
Master
Bedroom
Bedroom
Fig. 5—Example of a Floor Plan
• Assigning Zones
Task 1—Assess the homeowner’s goals for comfort and energy
savings.
Task 2—Conduct a site survey and make preliminary zone
assignments.
• Sizing the Equipment
Task 3—Calculate block load estimates and zone load estimates.
Task 4—Size the heating and cooling equipment.
• Laying Out and Sizing the Duct System
Task 5—Choose register and return locations.
Task 6—Determine bypass needs.
Task 7—Lay out supply ducts and locate dampers.
Task 8—Determine appropriate damper and duct sizes.
• Laying Out Zone Components
Task 9—Choose locations for zone sensors.
A. Assigning Zones
TASK 1—ASSESS THE HOMEOWNER’S GOALS FOR
COMFORT AND ENERGY SAVINGS
For a zoning system to be successful, it must meet the homeowner’s goals for comfort and/or energy savings. Therefore, it is
essential to understand the homeowner’s goals before beginning to
design the system. In some situations, a homeowner’s expectations
might not be realistic and it would be impossible to design a
system to meet those expectations. By identifying this problem
from the start, you can help the homeowner revise these expectations and avoid creating a dissatisfied customer.
In addition to understanding the homeowner’s general goals for the
zoning system, you need to understand exactly how the home’s
occupants will use each room or area in the home. Use the
Homeowner Survey provided in the Appendix to help you gather
information from the homeowner.
TASK 2—CONDUCT A SITE SURVEY AND MAKE
PRELIMINARY ZONE ASSIGNMENTS
Conducting a Site Survey
The purpose of conducting a site survey is to gather the information that you need to:
• Make zone assignments. Use the Floor Plan Worksheet
provided in the Appendix to draw a floor plan of the home.
Follow these guidelines:
Kitchen
Informal
Dining
Room
Living Room
Shaded
Family Room
Utility
Room
Shaded
— Provide the rough dimensions of each area or room.
— Indicate the location and relative size of doors, windows,
and skylights. In particular, identify any large glass areas
(exceeding 30 percent of the wall area).
— Indicate whether any trees or buildings cast shade on any of
the home’s exposures.
— Indicate the orientation of the home so you can determine
whether there are any rooms or areas facing south or west
where the solar heat load might be a factor when making zone
assignments.
Fig. 5 shows an example of a floor plan for a home, drawn as
part of a site survey.
• Calculate heating and cooling load estimates for the home
(Task 3). Gather the information required to use the method of
your choice for calculating these loads. If you have a worksheet
that you generally use to gather this information, feel free to
use it.
• Choose register and return locations (Task 5). Generally, the
Floor Plan Worksheet will provide sufficient information for
choosing register and return locations. In a retrofit installation,
indicate the location of existing duckwork, as well as heating
and cooling equipment.
• Lay out ducts and locate dampers (Task 6). Gather the
information about the home required to lay out ducts and locate
dampers using the method of your choice. If you have a
worksheet that you generally use to gather this information,
feel free to use it.
Making Preliminary Zone Assignments
The homeowner’s goals regarding comfort and energy savings
affect how many zones are appropriate for the system:
• In a system designed primarily for comfort, all zones usually
have comfort set points that remain relatively constant and that
have similar time schedules. Such a system may have a large
number of zones (5 to 8) of a relatively small size.
• In a system designed primarily for energy savings, there are
zones that are not used much of the time. Such a system must
have even larger ducts to guarantee proper airflow to the zones
that remain in use when some zones are unused. Such a system
generally must have a smaller number of zones of a relatively
larger size. In this case, you must be careful not to "over zone"
(assign too many zones).
When making zone assignments, use the information that you
gathered when conducting the site survey. Group areas that:
A98341
—5—
N
Bath
Bath
Bedroom
Large
WIndow
Master
Bedroom
Bedroom
Fig. 6—Example of Zoning Assignments
• Are in use around the same time of day. For example, it often
makes sense to assign all bedrooms to a single zone because
they are occupied only during the night time when other rooms
in the home are not occupied.
• Have similar heating and cooling needs.
• Are physically separated from other areas.
• Are on the same level of the home. For example, the rooms on
the upstairs level often have a different heating or cooling
demand when compared to rooms downstairs. The differences
can be due to the tendency for heat to rise, different use of
occupancy, and the roof heat load.
• Have similar exposures to external heating gains and losses.
For example, it often makes sense to assign rooms with large
amounts of glass and western or southern exposure to the same
zone.
• The homeowner intends to "set back" at the same time.
• Let you avoid extremely small zones that would cause the
airflow through the unit to become extremely low when only 1
zone requires conditioning.
If possible, discuss these considerations with the homeowner. Get
the homeowner’s input before making initial zone assignments.
Mark your preliminary zone assignments on the Floor Plan
Worksheet provided in the Appendix. Fig. 6 shows an example of
zoning assignments marked on a floor plan worksheet.
At this point, consider your zone assignments to be preliminary.
The next task helps you check whether the zone assignments are
feasible.
B. Sizing the Equipment
TASK 3—CALCULATE BLOCK LOAD ESTIMATES AND
ZONE LOAD ESTIMATES
Using the information that you gathered in Task 2, calculate both
heating and cooling load estimates for the entire home. These
estimates are used primarily for sizing the heating and cooling
equipment for the system.
Kitchen
Shaded
Utility
Room
Zone 1
Zone 2
Zone 3
Zone 4
A98342
Informal
Dining
Room
Living Room
Shaded
Family Room
The standard Btu load calculations used for non-zoned systems
apply equally well to zoned systems. Use a reliable method with
which you are comfortable.
After you have tentatively defined the zones for a home, calculate
individual peak heating and cooling load estimates (in Btu’s) for
each of the zones. Use a reliable method with which you are
comfortable to calculate the peak zone load estimates. Refer to the
information that you gathered in Task 2.
The peak zone load estimates are used to determine whether the
zone assignments you have made make sense. They also are used
to size the zone dampers and ductwork.
When a zone is recovering from being set back, the system must
supply additional capacity beyond the zone’s losses to change the
temperature. The farther the desired setback, the more capacity
must be added.
For zones that will be set back and that need reliable recovery,
multiply their calculated zone loss by a recovery factor of 1.25.
Use the larger zone load estimate when determining the size of the
damper and duct required for the zone.
TASK 4—SIZE HEATING AND COOLING EQUIPMENT
Zone Perfect Plus is designed for use with a furnace or fan coil in
conjunction with a condensing unit or heat pump with a thermostatic expansion valve (TXV). Zone Perfect Plus operates within
an airflow range of 1.5 to 6 tons in the cooling mode.
How to determine the appropriate size of heating and cooling
equipment is a challenge that is subject to much debate. In a
residential zoning system, there is a very good possibility that a
system will use all zones on a given day. For that reason, we
recommend that you select the size of heating and air conditioning
units based on either the home’s block heating load or block
cooling load (whichever is greatest). Select the size of the air
handling unit based on the unit with the largest required CFM.
However, because the system has the capability to not condition
some zones at any given time, and because it is essential to
—6—
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