©2025 Copeland LP.
026-1803 R13 Supervisor I&O User Guide 9 - 45
9.32.3 Temperature Control
HVAC Zone applications do not control temperature
themselves. HVAC Zone applications pass along the
setpoints that an HVAC unit will use. The individual unit is
responsible for controlling the setpoint using its own
temperature input.
The HVAC Zone application pass along eight different
setpoints, which are shown in Table 9-22. The application
that receives the setpoints can only use one cooling and one
heating setpoint. The pair of setpoints the application will use
determines whether the current season is SUMMER or
WINTER and whether the building is OCCUPIED or
UNOCCUPIED (both of which are supplied by the Zone).
9.32.4 HVAC Zone Temperature
Each MultiFlex RTU and AHU application has a space
temperature output that is equal to the unit’s current Control
Temperature. When associated with an HVAC Zone
application, this space temperature output is connected to
one of the 16 HVAC Zone Temperature inputs in the HVAC
Zone application. These 16 inputs are combined using a
user-defined combination method to yield the HVAC Zone
Temperature.
HVAC Zone Temperature provides an overview of the unit’s
performance in heating and cooling within the HVAC Zone.
The HVAC Zone Temperature can be used as a temperature
control input by one or all of the HVAC Zone’s application.
9.32.5 Economizer Control
An HVAC Zone application is responsible for analyzing
outside air conditions and determining if the conditions are
suitable for bringing in outside air. If the air condition is
suitable, the HVAC Zone sends a signal to its associated
HVAC units telling them that economization is OK. If not, it
sends a signal to disable economization.
It is up to the associated HVAC unit to process the
economization information and open the dampers.
9.32.6 Economization Enable
There are possible ways an HVAC Zone application may
determine when conditions are favorable for economization:
1. Enthalpy Switch - An enthalpy switch is a digital device
that is pre-set to detect when the temperature and
humidity levels are appropriate for economization. When
the conditions are appropriate, this switch sends an OK
(ON) signal to the Zone application. Otherwise, the switch
sends a NOT OK (OFF) signal.
2. Dewpoint Setpoint - A dewpoint probe measures the
dewpoint of the outside air and is compared to a setpoint.
If the outside air dewpoint is less than the setpoint,
economization is enabled. If it is higher than the setpoint,
economization is disabled.
3. Calculated Enthalpy - The HVAC Zone application
calculates the outside air enthalpy by reading the value
of a relative humidity sensor and an outdoor air
temperature sensor. This calculated enthalpy is
compared to a setpoint. If the enthalpy is less than the
setpoint, economization is enabled. If greater,
economization is disabled.
4. Dewpoint Fail-Safe - This is similar to method Dewpoint
Setpoint, except that an outdoor temperature sensor
value is compared to the setpoint instead of a dewpoint
probe’s value. This comparison is a poor substitute for
actual dewpoint readings and is recommended for use
as a fail-safe only. When possible, use humidity or
dewpoint sensors.
5. Temperature Comparison - The AHU Control application
simply compares the temperature of the inside air with
the temperature of the outside air. If the outside air is
cooler than the inside air, economization is enabled.
6. In vs. Out Enthalpy - This strategy requires indoor and
outdoor humidity sensors and also indoor and outdoor
temperature sensors. The enthalpy of the outdoor air is
calculated and com-pared to the enthalpy of the indoor
air. If the outdoor air enthalpy is less than the indoor air
enthalpy, economization is enabled. Otherwise,
economization is disabled.
You can choose a different method to use in summer and
winter months. Also, an alternate method may be specified
that will be used as a fail-safe when the primary method is not
available (due to sensor failure).
Table 9-22- Cooling/Heating Setpoints
Cooling Heating
SUMMER COOL OCC
SUMMER HEAT OCC
SUMMER COOL UOCC
SUMMER HEAT UOCC
WINTER COOL OCC
WINTER HEAT OCC
WINTER COOL UOCC
WINTER HEAT UOCC
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