Product data

Application data (cont)
Alarm configuration and application
This section describes the major alarm types that are avail-
able within the system. The alarm types are: space tem-
perature alarm (Comfort Trend), discharge air temperature
alarm, fan status alarm, filter status alert, IAQ status alarm,
communication failure alarm, and stuck gas valve alarm.
The section describes each alarm in detail: what control-
lers it works with; the sensors required for the alarm to be
activated; and how the alarm is configured, disabled, and
normalized. The description provides information on how
the alarm is applied and the necessary hardware required
for proper operation.
Space temperature alarm (Comfort Trend) — See
the Space Temperature Alarm table below for alarm
specifications.
SPACE TEMPERATURE ALARM
FUNCTION DESCRIPTION
Controllers
Monitor Thermostat/Zone
Controller
Sensor Required
None (Space Temperature
Sensor is in Thermostat)
Sensor Wiring
None, Sensor Integral to
Thermostat
Input
Comfort Trend Demand
Comfort Trend Time Limit
Output
SE-01 Comfort Trend Error
(Space Temperature Alarm)
Configuration Option
Comfort Trend Demand
Comfort Trend Time Limit
Configuration Values
Range 0° F to 25.5 F
Range 0 to 255 minutes
Configuration Increments
0.1° F
1 minute
Associated Functions None
Operation
A space temperature (Comfort Trend) alarm indicates
when the system is unable to maintain space temperature
comfort conditions. Space temperature alarms are an indi-
cation that the HVAC system operation has difficulty main-
taining zone space temperature. The temperature demand
of the space or zone is the difference between the set point
(either heating or cooling) and actual space temperature of
the zone.
When the demandof thezone exceedsthe ComfortTrend
Demand value, the thermostat begins to calculate the tem-
perature trend of the zone. The temperature trend is sim-
ply the ‘‘real time’’ ability of the space to lower or reduce
the temperature demand of the space. The time is mea-
sured during the period when the temperature trend does
not show improvement, or indicates conditions between set
point and space temperature are getting worse. When the
length of time measured reaches the Comfort Trend Time
Limit value, a space temperature alarm is initiated.
Configuration example
Occupied Space Cooling Set Point ...............72F
Occupied Space Heating Set Point ...............68F
Comfort Trend Demand .......................4.5F
Comfort Trend Time Limit .................7minutes
The system is operating normally without alarm during
the cooling mode. The trend of the space temperature in-
dicates that the system is unable to keep the space with-
in set points, and space temperature rises to 76.5 F. The
trend of the space temperature does not improve, and tem-
perature conditions are getting worse for at least 7 minutes.
At that time, a space temperature (Comfort Trend) alarm
(SE-01) is initiated. The alarm will automatically clear when
the system can properly maintain space temperature con-
ditions within the space.
The alarm is removed using the manual reset or by set-
ting demand to 0. The system will not return to normal
without being reset.
Discharge-air temperature alarm (Heat/Cool mode
error) — See Discharge Air Temperature Alarm table for
specifications.
DISCHARGE-AIR TEMPERATURE ALARM
FUNCTION DESCRIPTION
Controllers Monitor Thermostat
Sensor Required
Remote Duct Sensor (RDS):
Monitor Only Mode
Duct Temperature
Sensor: VVT Monitor Mode
Sensor Wiring
RDS: Wires to Terminal 13 and 15
Duct Temp Sensor: None,
Sensor Integral to Damper
Input Unit Discharge Air Temperature
Output
SE-07 Heat Mode Alarm,
SE-08 Cool Mode Alarm
Configuration Option
Heat Mode Alarm Set Point
Cool Mode Alarm Set Point
Configuration Values
Heating: Min 0° F, Max 140 F
Cooling: Min 0° F, Max 140 F
Configuration Increments 1° F
Associated Functions None
Operation
Heating mode — Alarm is issued when unit discharge tem-
perature is not above the heating mode error set point.
Cooling mode — Alarm is issued when unit discharge tem-
perature is not below the cooling mode error set point.
Configuration to normalize alarm
When unit discharge temperature rises above the heat mode
error set point, the heat mode alarm is normalized. When
unit discharge temperature drops below the cool mode er-
ror set point, the cool mode alarm is normalized.
For example, the Heating/Cooling Mode Error setpoints
are 90 and55 F. During a heat mode, after 10-minute heat-
ing period, ifdischarge temperature doesnot increaseabove
90 F, a heat mode error is generated. After discharge tem-
perature increases above 90 F, the alarm is normalized.
During cooling mode, after a 10-minute cooling period,
if discharge temperature does not drop below 55 F, a cool
mode error is generated. After the discharge temperature
decreases below 55 F, the alarm is normalized.
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