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The same equation can be used to determine the occupied
or maximum 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. 72 to det ermine 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. 72 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 confi guration for the CO
2
sensor should be 1800
ppm. T he EconoMi$er IV controller will output the 6.7
volts from the CO
2
sensor to the actuator when the CO
2
conce ntration in the space is at 1100 ppm. The DCV
setpoint may be left at 2 volts since the CO
2
sensor
voltage will be ignored by the EconoMi$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 result 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 selected anytime after the sensor is powered up.
(See Table 23.)
Use setting 1 or 2 for Bryant equipment. (See Table 23.)
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.
Table23–CO
2
Sensor Standard Settings
SETTING EQUIPMENT OUTPUT
VENTILATION
RATE
(cfm/Person)
ANALOG
OUTPUT
CO
2
CONTROL
RANGE
(ppm)
OPTIONAL
RELAY SETPOINT
(ppm)
RELAY
HYSTERESIS
(ppm)
1
Interface w/Standard
Building Control System
Propor tional Any
0 --- 10V
4 --- 20mA
0---2000 1000 50
2 Propor tional Any
2 --- 10V
7 --- 20mA
0---2000 1000 50
3 Exponential Any
0 --- 10V
4 --- 20mA
0---2000 1100 50
4
Economizer
Propor tional 15
0 --- 10V
4 --- 20mA
0---1100 1100 50
5 Propor tional 20
0 --- 10V
4 --- 20mA
0 --- 900 900 50
6 Exponential 15
0 --- 10V
4 --- 20mA
0---1100 1100 50
7 Exponential 20
0 --- 10V
4 --- 20mA
0 --- 900 900 50
8 Health & Safety Propor tional —
0 --- 10V
4 --- 20mA
0---9999 5000 500
9
Parking/Air Intakes/
Loading Docks
Propor tional —
0 --- 10V
4 --- 20mA
0---2000 700 50
580J