Carrier 48TC series, Инструкции по обслуживанию и техническому обслуживанию, Страница: 54 / 112

54
following equation may be used to determine the percent of out -
side air entering the building for a given damper position. For best
results, there should be at least a 10°F difference in outside-air and
return-air temperatures.
T
O
= Outdoor-Air Temperature
OA = Percent of Outdoor Air
T
R
= Return-Air Temperature
RA = Percent of Return Air
T
M
= Mixed-Air Temperature
Once base ventilation has been determined, set the minimum
damper position potentiometer to the correct position.
The same equation can be used to determine the occupied or max -
imum ventilation rate to the building. For example, an output of
3.6 volts to the actuator provides a base ventilation rate of 5% and
an output of 6.7 volts provides the maximum ventilation rate of
20% (or base plus 15 cfm per person). Use Fig. 74 to determine
the maximum setting of the CO
2
sensor. For example, an 1100
ppm setpoint relates to a 15 cfm per person design. Use the 1100
ppm curve on Fig. 74 to find the point when the CO
2
sensor output
will be 6.7 volts. Line up the point on the graph with the left side
of the chart to determine that the range configuration for the CO
2
sensor should be 1800 ppm. The EconoMi$er IV controller will
output the 6.7 volts from the CO
2
sensor to the actuator when the
CO
2
concentration in the space is at 1100 ppm. The DCV setpoint
may be left at 2 volts since the CO
2
sensor voltage will be ignored
by the EconoMi$er IV controller until it rises above the 3.6 volt
setting of the minimum position potentiometer.
Once the fully occupied damper position has been determined, set
the maximum damper demand control ventilation potentiometer
to this position. Do not set to the maximum position, as this can re -
sult in over-ventilation to the space and potential high humidity
levels.
CO
2
SENSOR CONFIGURATION
The CO
2
sensor has preset standard voltage settings that can be se -
lected anytime after the sensor is powered up. See Table 21.
Use setting 1 or 2 for Carrier equipment. See Table 21.
1. Press Clear and Mode buttons. Hold at least 5 seconds
until the sensor enters the Edit mode.
2. Press Mode twice. The STDSET Menu will appear.
3. Use the Up/Down button to select the preset number. (See
Table 21.)
4. Press Enter to lock in the selection.
5. Press Mode to exit and resume normal operation.
* CRENTDIF004A00 and CRTEMPSN002A00 accessories are used
on many different base units. As such, these kits may contain parts that
will not be needed for installation.
† 33ZCSENCO2 is an accessory CO
2
sensor.
** 33ZCASPCO2 is an accessory aspirator box required for duct-
mounted applications.
†† CRCBDIOX005A00 is an accessory that contains both 33ZCSEN-
CO2 and 33ZCASPCO2 accessories.
The custom settings of the CO
2
sensor can be changed any time
after the sensor is energized. Follow the steps below to change the
non-standard settings:
1. Press Clear and Mode buttons. Hold at least 5 seconds
until the sensor enters the Edit mode.
2. Press Mode twice. The STDSET Menu will appear.
3. Use the Up/Down button to toggle to the NONSTD menu
and press Enter.
4. Use the Up/Down button to toggle through each of the
nine variables, starting with Altitude, until the desired set -
ting is reached.
5. Press Mode to move through the variables.
6. Press Enter to lock in the selection, then press Mode to
continue to the next variable.
DEHUMIDIFICATION OF FRESH AIR WITH DCV
(DEMAND CONTROLLED VENTILATION) CONTROL
If normal rooftop heating and cooling operation is not adequate for
the outdoor humidity level, an energy recovery unit and/or a dehu -
midification option should be considered.
ECONOMI$ER IV PREPARATION
This procedure is used to prepare the EconoMi$er IV for trouble
-
shooting. No troubleshooting or testing is done by performing the
following procedure.
NOTE: This procedure requires a 9-v battery, 1.2 kilo-ohm resis -
tor, and a 5.6 kilo-ohm resistor, which are not supplied with the
EconoMi$er IV.
1. Disconnect power at TR and TR1. All LEDs should be off.
Exhaust fan contacts should be open.
2. Disconnect device at P and P1.
3. Jumper P to P1.
4. Disconnect wires at T and T1. Place 5.6 kilo-ohm resistor
across T and T1.
5. Jumper TR to 1.
6. Jumper TR to N.
(T
O
x
OA
) + (T
R
x
RA
) = T
M
100 100
Table 21 — EconoMi$er IV Sensor Usage
APPLICATION
ECONOMI$ER IV WITH OUTDOOR-AIR
DRY BULB SENSOR
Accessories Required
Outdoor Air
Dry Bulb
None. The outdoor air dry bulb sensor
is factory installed.
Differential
Dry Bulb
CRTEMPSN002A00*
Single Enthalpy HH57AC078
Differential
Enthalpy
HH57AC078 and CRENTDIF004A00*
CO
2
for DCV
Control using a
Wall-Mounted
CO
2
Sensor
33ZCSENCO2
CO
2
for DCV
Control using a
Duct-Mounted
CO
2
Sensor
33ZCSENCO2† and
33ZCASPCO2**
OR CRCBDIOX005A00††
IMPORTANT: Be sure to record the positions of all poten -
tiometers before starting troubleshooting.