Product data

Application data
Supplemental heat
Supplemental heat is used to provide control of zone duct
or perimeter baseboard heat. It can either augment the heat
of the central unit or be the primary source of heat. Supple-
mental heat can only be controlled by a zone controller.
The staging of the heating mode is dependent on the
type of supplemental heat.
Parallel fan box — With 1.0° F demand, the fan is ener-
gized. With 2.0° F demand, the first stage of heat is ener-
gized. With 2.5° F demand, the second stage of heat is
energized.
Series fan box — The fan runs continuously during oc-
cupied mode. With 1.5° F demand, the first stage of heat is
energized. With 2.0° F demand, the second stage of heat is
energized.
Baseboard — The fan is not used. With 1.5° F demand,
the first stage of heat is energized. With 2.0° F demand,
the second stage of heat is energized.
Duct mounted heat — With1.5° Fdemand, thefirst stage
of heat is energized. With 2.0° F demand, the second stage
of heat is energized. Fan use requires a system fan. The
zone controller requests the monitor thermostat to turn on
the system fan. If the VVTt system is hydronic, the first
stage is energized 30 seconds prior to the request for sys-
tem fan.
During supplemental heat, the zone controller will work
to maintain the zone set points. During supplemental heat
mode requiring thesystem fan(duct mountedheat), thezone
controller maintains the damper at the configured Supple-
mental Heat Damper Position. If using a series fan box,
parallel fan box, or baseboard heat, the damper is main-
tained at the minimum damper position.
Communications
The Carrier Comfort system is a communicating system of
zone controllingthermostats. Through communications, in-
formation is shared betweenzones, whichoptimizes theuse
of the HVAC equipment. Communications also permit the
installer and owner to view and monitor the overall opera-
tion of the system.
Communications take place over a 3-wire shielded cable
which is wired to the thermostat connector block. The wir-
ing must be made in daisy chain fashion from one thermo-
stat to another.
Once thecommunication cablehas been installed and the
thermostats have been connected to the cable through the
connector blocks, it is necessary to give the thermostat a
unique identity on the communication bus. This is accom-
plished through the device address. The device address has
two parts: the element address (specific to the device) and
the bus address (the branch of the communication bus the
device is on). If only one continuous link of devices exists,
the bus address would be 0.
It is possible to break the system into several branches or
subsystems.Thesebranches wouldbecalledsecondary buses.
A bridge is needed to create a secondary bus. To correctly
address the devices under the bridge, all thermostats must
have a bus address which is identical to the element address
of the bridge. For example, if the bridge (which is on the
main bus) has a bus/element address of 0,75, the thermo-
stats on thebridge wouldhave abus addressof 75. Branches
may be added to separate various systems or to reduce the
communication traffic on the main bus.
The VVT system monitor thermostats are available in
3 different zone capacity models which allow it to com-
municate with 4, 16, or 32 system components. When
addressing the zone controllers, it is not necessary to have
sequentially addressed zone controllers physically next to
each other. Within a VVT system, the monitor thermostat
must have the highest address. The bypass controller and
zone controllers are addressed sequentially below that.
Selection of damper sizes
Allzone dampers(roundand rectangular),areequipped with:
supply air temperature sensors, a plug-in wiring header for
the relay pack, a plug-in wiring header for available sensors
(humidity, temperature, pressure, or CO
2
).
Based on required airflow to the zone, round dampers
are available in 6 sizes to provide optimum airflow for low
pressure applications (1.0 in. wg). Round dampers should
beselected basedon thecfm(nominal andmaximum) shown
in the table below.
ROUND DAMPER SIZES
MODEL
SIZE
(diam. in.)
ZONE CFM
Nominal
(800 fpm)
Maximum
(1200 fpm)
ZD-06 6 160 240
ZD-08 8 280 420
ZD-10 10 440 660
ZD-12 12 630 950
ZD-14 14 850 1275
ZD-16 16 1125 1675
Rectangular dampers should be selected based on the cfm
(nominal and maximum) shown in the table below.
RECTANGULAR DAMPER SIZES
MODEL
SIZE
(H x W in.)
ZONE CFM
Nominal
(800 fpm)
Maximum
(1200 fpm)
RD0810 8 x 10 410 610
RD0814 8 x 14 560 825
RD0818 8 x 18 725 1075
RD0824 8 x 24 925 1375
For applications requiring 2 or more dampers working to-
gether to provide the required total airflow, the dampers
have the capability of being wired together. If space restric-
tions do not allow the use of a 14-in. damper, two 10-in.
round dampers could be wired together to provide the re-
quired airflow. In these situations, only one monitor ther-
mostat or zone controller is needed to provide control. It is
wired (5-wire cable) to one of the 2 dampers which is des-
ignated the masterdamper. Wiring from themaster damper
tothe additional(slave)dampers isaccomplishedusing 3-wire
cable. The master damper is sequenced from the monitor
thermostatorzone controllerwhiletheslave damper(s) modu-
late based upon the movement of the master damper.
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