Bryant Preferred Series Service And Maintenance Instructions page 52

the equipment, the maximum ventilation rate must be evaluated
for design conditions. The maximum damper position must be cal-
culated to provide the desired fresh air.
Typically the maximum ventilation rate will be about 5 to 10%
more than the typical cfm required per person, using normal out-
side air design criteria.
A proportional anticipatory strategy should be taken with the fol-
lowing conditions: a zone with a large area, varied occupancy, and
equipment that cannot exceed the required ventilation rate at de-
sign conditions. Exceeding the required ventilation rate means the
equipment can condition air at a maximum ventilation rate that is
greater than the required ventilation rate for maximum occupancy.
A proportional-anticipatory strategy will cause the fresh air sup-
plied to increase as the room CO
CO setpoint has not been reached. By the time the CO
2
reaches the setpoint, the damper will be at maximum ventilation
and should maintain the setpoint.
In order to have the CO sensor control the EconoMi$er damper in
2
this manner, first determine the damper voltage output for mini-
mum or base ventilation. Base ventilation is the ventilation re-
quired to remove contaminants during unoccupied periods. The
following equation may be used to determine the percent of
outside air entering the building for a given damper position. For
best results, there should be at least a 10 degree difference in out-
side-air and return-air temperatures.
OA
(T x ) + (T
O
100
T = Outdoor-Air Temperature
O
OA = Percent of Outdoor Air
T = Return-Air Temperature
R
RA = Percent of Return Air
T = Mixed-Air Temperature
M
Once base ventilation has been determined, set the minimum
damper position potentiometer to the correct position.
The same equation can be used to determine the occupied or max-
imum ventilation rate to the building. For example, an output of
3.6 volts to the actuator provides a base ventilation rate of 5% and
an output of 6.7 volts provides the maximum ventilation rate of
20% (or base plus 15 cfm per person). Use Fig. 68 to determine
the maximum setting of the CO
1100 ppm setpoint relates to a 15 cfm per person design. Use the
SETTING EQUIPMENT
1
Interface with
Standard
2
Building
Control System
3
4
5
Economizer
6
7
Health and
8
Safety
Parking/Air
Intakes/Loading
9
Docks
level increases even though the
2
RA
x ) = T
R M
100
sensor. For example, an
2
Table 22 — CO
VENTILATION
OUTPUT RATE
(cfm/PERSON)
Proportional
Proportional
Exponential
Proportional
Proportional
Exponential
Exponential
Proportional
Proportional
1100 ppm curve on Fig. 68 to find the point when the CO
output will be 6.7 volts. Line up the point on the graph with the
left side of the chart to determine that the range configuration for
the CO sensor should be 1800 ppm. The EconoMi$er IV control-
2
ler will output the 6.7 volts from the CO
when the CO
2
DCV setpoint may be left at 2 volts since the CO
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 controlled ventilation potentiome-
ter 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.
level
CO SENSOR CONFIGURATION
2
2
The CO sensor has preset standard voltage settings that can be se-
2
lected anytime after the sensor is powered up. See Table 22 and
Fig. 69.
Use setting 1 or 2 for Bryant equipment. See Table 22.
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 22.)
4. Press Enter to lock in the selection.
5. Press Mode to exit and resume normal operation.
Sensor Standard Settings
2
ANALOG
OUTPUT
0-10V
Any
4-20mA
2-10V
Any
4-20mA
0-10V
Any
4-20mA
0-10V
15
4-20mA
0-10V
20
4-20mA
0-10V
15
4-20mA
0-10V
20
4-20mA
0-10V
—
4-20mA
0-10V
—
4-20mA
52
2
concentration in the space is at 1100 ppm. The
clear mode
enter
Fig. 69 — CO Sensor
2
OPTIONAL
CO CONTROL RELAY
2
RANGE (ppm) SETPOINT
(ppm)
0-2000 1000
0-2000 1000
0-2000 1100
0-1100 1100
0-900 900
0-1100 1100
0-900 900
0-9999 5000
0-2000 700
sensor
2
sensor to the actuator
sensor voltage
2
RELAY
HYSTERESIS
(ppm)
50
50
50
50
50
50
50
500
50