5-10 • Site Supervisor Controller User Guide 2.0 026-1800 Rev 3 02-AUG-2016
5.6 HVAC Control
The HVAC control application controls HVAC
equipment, rooftop units, or air handlers.
The number of AHU applications allowed is based on
the total number of applications allowed on the device.
The AHU application provides basic functionality to
control a typical packaged HVAC unit. The packaged
HVAC units have up to four stages of heating and cooling
and may have a fresh air damper installed to allow free-air
cooling (economization) when conditions permit.
5.6.1 Active Setpoint
Determination
The active setpoint used by the heating and cooling
logic is selected from the following setpoint inputs:
• SUMMER HEAT OCC - This field is the setpoint
that is used for heating control during summer
occupied mode. If this AHU has been assigned to a
Zone application, this input is automatically be
defined so that the Zone application supplies the
setpoint value. You do not need to change this
definition.
• SUMMER HEAT UOC - This field is the setpoint
that is used for heating control during Summer
Unoccupied mode. If this AHU has been assigned
to a Zone application, this input is automatically
defined so that the Zone application supplies the
setpoint value. You do not need to change this
definition.
• SUMMER COOL OCC - This field is the setpoint
that is used for cooling control during Summer
Occupied mode. If this AHU has been assigned to a
Zone application, this input is automatically defined
so that the Zone application supplies the setpoint
value. You do not need to change this definition.
• SUMMER COOL UOC - This field is the setpoint
that is used for cooling control during Summer
Unoccupied mode. If this AHU has been assigned
to a Zone application, this input is automatically
defined so that the Zone application supplies the
setpoint value. You do not need to change this defi-
nition.
• WINTER HEAT OCC - This field is the setpoint
that is used for heating control during Winter
Occupied mode. If this AHU has been assigned to a
Zone application, this input is automatically defined
so that the Zone application supplies the setpoint
value. You do not need to change this definition.
• WINTER HEAT UOC - This field is the setpoint
that is used for heating control during Winter
Unoccupied mode. If this AHU has been assigned
to a Zone application, this input is automatically
defined so that the Zone application supplies the
setpoint value. You do not need to change this
definition.
• WINTER COOL OCC - This field is the setpoint
that is used for cooling control during Winter
Occupied mode. If this AHU has been assigned to a
Zone application, this input is automatically defined
so that the Zone application supplies the setpoint
value. You do not need to change this definition.
• WINTER COOL UOC - This field is the setpoint
that is used for cooling control during Winter
Unoccupied mode. Enter the desired setpoint value
in this field. If this AHU has been assigned to a
Zone application, this input is automatically defined
so that the Zone application supplies the setpoint
value. You do not need to change this definition.
5.6.2 Setpoint Reset
The active setpoint may be changed by a Reset Sensor
input. A Reset Sensor is used to allow reset on the setpoint
based on an external sensor, such as humidity or outside
temperature. The user selects an input range for the sensor
and a maximum offset. The offset value is calculated
proportional to the output range while the input value is
calculated proportional to the input range.
5.6.3 Demand Shed
The active setpoint may be changed by the primary or
secondary demand shed inputs. If either demand shed is
active (ON), the active setpoint is adjusted by the amount
specified by the demand bump parameters.
Control Temperature Determination
The AHU determines which sensor should be used to
provide overall control to the space being conditioned, for
example, the control temperature. The control temperature
NOTE: The AHU application provides support
for Constant Air Volume (CAV) systems only.
The Variable Air Volume (VAV) systems are
not supported.
NOTE: The active setpoint chosen from the
above list is based on the current occupancy
status, the season (Summer/Winter), and
whether the AHU is in heating or cooling
mode. If the AHU is neither heating nor cooling, the
last mode used will determine the active setpoint.
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