Product data
Application data (cont)
If the outdoor humidity is above the user-configured set
point, the system will not energize the economizer relay.
The outdoor humidity must be read and broadcast by an-
other device on the communication bus (such as a Comfort
Controller). If the monitor thermostat is not receiving out-
side humidity, the humidity lockout will not function.
If the outdoor-air temperature is above or below the user-
configured set point, thesystem willnot energize theecono-
mizer relay. The outdoor air temperature can be read by an
outdoorair sensorwired tothe monitorthermostator broad-
cast by another device on the communication bus. If the
monitor thermostat is not receiving outdoor air tempera-
ture, system will not energize the economizer relay.
The monitor thermostat has an IAQ alarm delay func-
tion which configures how long the monitor thermostat will
wait before sending an IAQ alarm to the communication
bus.
Zone controller — During the time that the zone control-
ler is participating in the IAQ sequence, the zone controller
positions its damper at the maximum damper position for
pressure dependent applications and at the cfm/airflow set
point for pressureindependent applications.If thezone con-
troller is equipped with an optional CHR-06W or CHR-06
relay, the AUX contacts on the relay are energized when
the monitor thermostat energizes the economizer on the
first zone to indicate local IAQ mode. Only the zone con-
troller economizer which signalled first is energized. When
that zone IAQ is satisfied, the next zone with local IAQ will
energize AUX.
Thezone controllerhasa temperature resetfunctionwhich
will allow fresh air to be brought into a zone even if the
temperature set points are exceeded. When fresh heated
air is brought into a heated zone, or conditioned cooled air
is brought into a cooled zone, the zone temperature may
rise ordrop beyond user-configured limits. The temperature
reset function allows the zone temperature to rise or drop a
user-configured limit beyond the set point to allow the in-
door air quality time to improve.
The zone controller has a system IAQ configuration op-
tion which configures the zone controller to participate in
system IAQ mode or to ignore a system IAQ mode.
The zone controller has an IAQ sensor configuration op-
tion which is used if an IAQ sensor is attached to the zone
controller for local IAQ.
The zone controller has alarm delay function which con-
figures how long the zone controller will wait before send-
ing an IAQ alarm to the communication bus.
Bypass controller — When an IAQ sensor is connected
to the bypass controller, it is the system IAQ sensor. The
bypass controller maintains the IAQ pressure set point dur-
ing IAQ mode. After the bypass controller has satisfied the
IAQ alarm, the IAQ system alarm will continue for4
1
⁄
2
min-
utes to further reduce the CO
2
levels. If the bypass control-
ler has an AUX relay, it can be used to energize a system
exhaust fan. The AUX contacts on the relay are energized
when the monitor thermostat energizes the economizer.
The bypass controller has an IAQ sensor configuration
option which is used if an IAQ sensor is attached to the by-
pass controller for system IAQ.
The bypass controller IAQ pressure set point is main-
tained by the bypass controller during system IAQ oper-
ation. This is usually set higher than normal operating pres-
sure in order to force more air into the zones that are par-
ticipating in system IAQ. This helps to quickly eliminate the
IAQ alarm.
The bypass controllerhas alarm delay function whichcon-
figures how long the bypass controller will wait before send-
ing an IAQ alarm to the communication bus.
Pressure independent systems
Pressure independent (PI) operation refers to maintaining a
specific airflow into a space, independent of the upstream
static pressure. Pressure independent operation should be
used: when a specific number of air changes every hour is
needed, when using a high pressure system such as a VAV
air handler, or when the cfm entering a space needs to be
monitored.
The equipment needed for a PI zone is: a zone damper,
a pressure sensor, a set of PSP or velocity pressure pickup
tubes, and a zone controller.
Thepressure sensor mustbelocated inaconditionedspace
where the ambient temperature is between 50 and 115 F
for accurate low pressure readings.
The PSP or velocity pressure pickup tubes need to be lo-
cated in an area of laminar flow. Laminar flow requires a
minimum of 1
1
⁄
2
duct diameters down stream and 5
1
⁄
2
duct
diameters upstream of the straight duct.
The minimum airflow at the PSP pickup tube location
must be equal or greater to 896 fpm (.05 in. wg of velocity
pressure). The PSP pickup tubes cannot accurately read air-
flow below this value. To make up for low flow require-
ments, a section of the ductwork upstream of the damper
may need to be downsized.
Retrofit and planned renovation applications
Retrofit and planned renovation are the two major areas
where new controls systems are applied to existing build-
ings. Upgrading controls or dampers for a job is a typical
retrofit application. Major modification of a non-zoned sys-
tem to a zoned system is beyond the scope of a typical ret-
rofit application.
For a planned renovation, the scope of the application is
greater than a retrofit application. In a planned renovation,
the unit and controls are usually upgraded. The duct layout
maybe extendedandzoning damper actuatorsmay be added
for additional comfort control.
Typically, any existing ductwork and dampers will remain
in place. To upgrade a series of pneumatic damper controls
to electronic Carrier Comfort System controls, the existing
ductwork and dampers do not need to be removed. The
pneumatic actuators are removed from the damper or box,
and the new electronic actuator is installed in its place.
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