Carrier 33CS Installation, Service, And Troubleshooting Instructions Download Page 29

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When the CO

level exceeds the preset level (factory con-

figuration is 1000 ppm and cannot be changed without optional
software), the sensor signals the TEMP system thermostat. The
TEMP system thermostat energizes the indoor-fan motor (if
not already running) for 5 to 30 minutes (field-configured). If
the Auxiliary Relay has been configured for IAQ operation, the
TEMP system thermostat energizes the relay. This is intended
for use with an economizer, but can be wired to an exhaust fan
or HRV (Heat Recovery Ventilator). If used with an economiz-
er, the economizer moves to the minimum position and the in-
door fan circulates the air throughout the occupied space.

The TEMP system has 3 lockout features which will pre-

vent IAQ mode if the outdoor humidity is too high or the out-
door temperature is too high or too low. When the TEMP sys-
tem thermostat energizes the auxiliary relay, it energizes the
system fan.

At the end of the 5 to 30 minutes, if the CO

level still ex-

ceeds the set point, the indoor fan will stay energized. The
economizer damper opens. This forces fresh outside air to enter
the zone with deficient IAQ. When the IAQ level drops below
the IAQ set point, the economizer returns to its standard operat-
ing mode.

When the system is bringing in additional outside air, the

thermostat is reset 0 to 10° F (field-configured) above and be-
low the original set point to allow the outside air to circulate
before the heating or cooling mode is initiated. The TEMP sys-
tem thermostat will display status when the system is in this
mode.
CLEARING THE ALARM — To clear a system error, use the
Unit Reset function. The Unit Reset function is in category 7,
option 11. The default is OFF. Use the left set point buttons to
set the option to ON. The TEMP system thermostat will reset
all errors.

Stuck Gas Valve Alarm —

Refer to Table 11 for Stuck

Gas Valve alarm specifications.

Table 11 — Stuck Gas Valve Alarm

OPERATION — The Stuck Gas Valve sequence is used to
allow the system to properly react to a failure mode of the
HVAC unit when the gas valve becomes stuck in the open
position. When this condition exists, the unit is unable to shut
off the heat. To minimize this problem, the internal limit switch
trips causing the indoor fan to turn on and remain on until the
gas is manually shut off and the heat exchanger cools to nor-
mal temperatures.
During No System Mode — If the duct temperature rises to
greater than 175 F, the indoor fan is started. The fan will remain
on if that temperature does not drop below 150 F after 3 min-
utes. A Stuck Gas Valve alarm (SE13) will be initiated.

During a Cooling Mode — If the duct temperature does not
drop below 80 F within 10 minutes, the cooling mode will be
dropped for 10 minutes. The ‘‘No System Mode’’ logic will
test for this condition.
During a Heating Mode — No action is required in this mode.
CONFIGURATION TO ACTIVATE ALARM — No configu-
ration is needed to activate this alarm.
CONFIGURATION TO NORMALIZE ALARM — To
remove this alarm, follow the procedure to clear the alarm
from the thermostat and network using manual reset.
CLEARING THE ALARM FROM THE THERMOSTAT —
The alarm can be cleared or erased from the system in 2 ways:
• Cycle power to the thermostat off, then on.
• Initiate a reset by switching the Unit Reset option to the ON

configuration (category 7, option 11).

NETWORK ACCESSIBLE VARIABLES

When using network access software, the following tables

can be accessed. The variables in the tables can be read, writ-
ten, or forced to a certain value. The TEMP system thermostat
point display table is shown in Table 12. Other network soft-
ware access tables are shown in Table 13.

Table 12 — TEMP System Thermostat Point

Display Table

LEGEND

*Forcing the system fan will cause any energized system stages to

turn off.

†If Auxiliary Relay is configured as 0 or 1, the point can be forced

with no other effect. Other configurations will cause the system
stages and fan to turn off.

FUNCTION

DESCRIPTION

Controllers

TEMP System Thermostat

Sensor Required