Table of Contents
Advertisement
APPENDIX C — VAV ZONE CONTROLLER - SUBMITTAL EXAMPLE
CODE
CATALOG #
BACnet VARIABLE AIR VOLUME COOLING WITH ON/OFF HOT WATER HEAT
CONTROL PACKAGE NO. 4243
Application:
Single duct units are designed to provide accurate variable
air volume (VAV) temperature control with a minimum
amount of energy consumption. A typical application is
shown in Fig. 1. A wall-mounted space temperature (SPT)
sensor located in each zone will sense load requirements
and activate the control sequence to accommodate cooling
or heating. Load requirements and sound level acceptability
govern terminal sizing. When reheat is required, the
controller can increase airflow to a user-defined
reheat airflow set point to ensure sufficient air quantity
through the heating coil. It is important that the correct
reheat airflow be selected to ensure that sufficient Btu's
can be delivered to meet load requirements. The airflow
will be reduced to the minimum cooling airflow set point
after reheat is no longer required. This control package
provides the following sequences of operation:
A. Cooling: (refer to numbers on flow diagram [Fig. 2])
1. 1-2 indicates that maximum flow is established by the
user-defined maximum cooling airflow set point until
the zone comes under control at 2.
2. Beginning at 2, the flow is regulated over a throttling
range by the damper until the minimum cooling airflow
set point is reached at 3.
3. 3-4 indicates that, should the zone temperature
continue to fall the damper will hold the user-defined
minimum cooling airflow set point.
4. It must be noted that the minimum cooling airflow
set point could be set to zero by the user. In this case,
the damper will hold a fully closed position if the zone
temperature continues to fall.
B. Hot water reheat: (when the primary air source is cooling,
refer to numbers on flow diagram)
1. Should the zone temperature fall below the occupied
heating set point, the Occupied Heating mode is in
effect at 4.
PRODUCT INFORMATION IS SUBJECT TO CHANGE WITHOUT NOTICE.
JOB NAME
BUYER
THIS DOCUMENT IS THE PROPERTY OF
CARRIER CORPORATION AND IS DELIVERED
UPON THE EXPRESS CONDITION THAT
THE CONTENTS WILL NOT BE DISCLOSED
O R
CORPORATION'S WRITTEN CONSENT
SUPPLY
SUPPLY
AIR
AIR
DAMPER
AIRFLOW
DAMPER
SENSOR
ACTUATOR
ZONE
CONTROLLER
24 VAC
Figure 1 - Single Duct Air Terminal with Hot Water or Steam Heat
JOB NUMBER
BUYER #
S U B M I S S I O N O F T H E S E
DRAWINGS OR DOCUMENTS
D O E S N O T C O N S T I T U T E
PA R T
P E R F O R M A N C E
U S E D
W I T H O U T
C A R R I E R
O R
A C C E P TA N C E
CONTRACT
2. At 5, the flow is increased to the user-defined reheat
airflow set point. The on/off hot water valve will open to
provide heating and satisfy the load requirements. The
valve is controlled so as not to exceed the maximum
discharge temperature limit.
3. When the zone temperature rises above the occupied
heating set point, the on/off hot water valve will close,
the Ventilation mode is reactivated at 4, and the airflow
is reduced to the minimum cooling airflow set point.
C. Heating: (when the primary air source is providing heated
air, refer to numbers on flow diagram)
1. Should the zone temperature fall below the occupied
heating set point, the Occupied Heating mode is in
effect at 4'.
2. The damper is throttled between the user-defined
minimum heating airflow set point at 4' and the user-
defined maximum heating airflow set point at 6. The
hot water valve will operate as required to supplement
the primary air temperature and controlled so as not
to exceed the maximum discharge temperature limit.
3. The control may be configured to provide constant
volume heating. In that case the damper will maintain
the minimum heating airflow set point at 4' to supply a
constant volume of heated air to the zone. If the tem-
perature of the primary air is insufficient to meet the
zone's heating requirements, the hot water valve will
operate as required to supplement the primary air. The
valve is controlled so as not to exceed the maximum
discharge temperature limit.
D. Unoccupied time period: (cooling)
When the unoccupied period is reached, the user-defined
occupied cooling set point is reset upward to a user-
defined unoccupied cooling set point. The damper will
operate in the same manner (as per A) during the unoc-
cupied period, using the unoccupied cooling set point.
HEAT COIL
LEAVING AIR
TEMPERATURE
HEAT
SENSOR
VALVE
SPACE
TEMPERATURE
SENSOR
BACnet
MS/TP
LOCATION
SHEET
45
VARIABLE AIR VOLUME
O F
LEAVING
AIR
PAGE NUMBER
DRAWING NUMBER
1 OF 3
3 5 E D - 4 2 4 3
35
ED
6/15/2010
Advertisement
Table of Contents
