Emerson iPro.Genius, Инструкция по установке и эксплуатации

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24 • Outside Air Control 026-1727 Rev 3
7.7.3.3. Economization Enabling
Strategy
When communicating with the E2, the DAC only
allows economization if it receives an economizer
enable signal from the E2. It does not use other
strategies to enable the economizer. However, in
standalone mode, the DAC has multiple user
selectable strategies available for determining
whether outside air conditions are favorable for
economization. Each method of economization
checking has a failsafe in case one of the sensors
required for the strategy becomes unavailable.
1. Dewpoint Setpoint – When selected, this
method requires an outside temperature and
humidity sensor to be connected to the
controller. Using these sensors, an outside
dewpoint value is calculated. When the
outside dewpoint is less than the dewpoint
setpoint, economization will be enabled. If
the outside humidity sensor fails, the
controller will revert to the Dry Bulb
Compare method. If the outside temperature
sensor fails, economization will be disabled.
2. Enthalpy Comparison – When selected, this
method requires an inside and outside
humidity sensor as well as an outside
temperature sensor to be connected to the
controller. Using these sensors, both inside
and outside enthalpy values are calculated.
When outside enthalpy is less than inside
enthalpy, economization will be enabled. If
the outside humidity sensor fails, the
application will revert to the Dry Bulb
Compare method. If an inside temperature or
humidity sensor fails, the application will
revert to using the Enthalpy Setpoint method.
If the outside temperature sensor fails,
economization will be disabled.
3. Enthalpy Setpoint – When selected, this
method requires an outside humidity and
temperature sensor to be connected to the
controller. Using these sensors, an outside
enthalpy is calculated. When the outside
enthalpy is less than the enthalpy setpoint,
economization will be enabled. If the outside
humidity sensor fails, the application will
revert to the Dry Bulb Compare method. If
the outside temperature sensor fails,
economization will be disabled.
4. Dry Bulb Compare – When selected, this
method requires an outside temperature
sensor to be connected to the controller.
When the outside temperature is less than the
inside temperature by at least 2°F,
economization will be enabled. If the outside
temperature sensor fails, economization will
be disabled.
5. E2 Zone Enable (BAS) – This method is
always used when the DAC is connected to
the E2. The controller will read the value of
the ECONOMIZATION output from the E2
zone and enable economization based on that
value. The E2 zone must be programmed
with its own method of economization
checking ( refer to the E2 user manual

026-1610/1614 and on-line help for HVAC
Zone application setup instructions ).
7.7.4. Smoke Detection
The DAC may be programmed with a Smoke
Detector input, which accepts a dry-contact digital
signal from a smoke alarm or a building control
network. When the smoke detector contact closes to
indicate smoke has been detected, the controller will
enter the Emergency Shutdown mode and all of the
DAC’s heating/cooling and fans will be overridden
OFF and the outside air damper will be closed.
7.7.5. Priority When Economization,
CO2 Control, and Make-up Air
are Used Together
When Economization, CO2 and Make-up Air
control are used together in the same DAC, it will
control a two-position damper using OR logic (OPEN
if one or more strategies require it to be open,
CLOSED if none do not require it to be open).
Variable-position dampers will be controlled
based on which control calls for the highest
percentage. In other words, if the damper needs to be
set to 60% to satisfy CO2 fresh air requirements and
40% to satisfy the economization mixed air
temperature setpoint, the damper will be opened to
60%.
7.7.6. Return Damper Control
An optional modulating return air damper may be
connected to the DAC. When connected, the return air
damper will modulate inversely proportional to the
outside air damper. For example, if the outside air
damper is at 10%, the return air damper will be at
90%. If the outside air damper goes to 100%, the
return air damper will go to 0%.
During dehumidification, and if a return air bypass
damper connected to the DAC, the return air damper
may deviate from its standard calculated position to