Bryant Preferred Series Service And Maintenance Instructions page 51

control, turn the enthalpy setpoint potentiometer fully clockwise to
the D setting.
INDOOR AIR QUALITY (IAQ) SENSOR INPUT
The IAQ input can be used for demand controlled ventilation con-
trol based on the level of CO
duct.
Mount the accessory IAQ sensor according to manufacturer speci-
fications. The IAQ sensor should be wired to the AQ and AQ1 ter-
minals of the controller. Adjust the DCV potentiometers to corre-
spond to the DCV voltage output of the indoor air quality sensor at
the user-determined setpoint. See Fig. 68.
If a separate field-supplied transformer is used to power the IAQ
sensor, the sensor must not be grounded or the EconoMi$er IV
control board will be damaged.
When using demand ventilation, the minimum damper position
represents the minimum ventilation position for VOC (volatile or-
ganic compounds) ventilation requirements. The maximum de-
mand ventilation position is used for fully occupied ventilation.
When demand controlled ventilation is not being used, the mini-
mum position potentiometer should be used to set the occupied
ventilation position. The maximum demand ventilation position
should be turned fully clockwise.
CO SENSOR MAX RANGE SETTING
2
6000
5000
4000
3000
2000
1000
0
2 3 4
DAMPER VOLTAGE FOR MAX VENTILATION RATE
Fig. 68 — CO Sensor Maximum Range Settings
2
EXHAUST SETPOINT ADJUSTMENT
The exhaust setpoint will determine when the exhaust fan runs
based on damper position (if accessory power exhaust is in-
stalled). The setpoint is modified with the Exhaust Fan Setpoint
(EXH SET) potentiometer. See Fig. 63. The setpoint represents
the damper position above which the exhaust fans will be turned
on. When there is a call for exhaust, the EconoMi$er IV controller
provides a 45 ± 15 second delay before exhaust fan activation to
allow the dampers to open. This delay allows the damper to reach
the appropriate position to avoid unnecessary fan overload.
MINIMUM POSITION CONTROL
There is a minimum damper position potentiometer on the
EconoMi$er IV controller. See Fig. 63. The minimum damper po-
sition maintains the minimum airflow into the building during the
occupied period.
When using demand ventilation, the minimum damper position
represents the minimum ventilation position for Volatile Organic
Compound (VOC) ventilation requirements. The maximum de-
mand ventilation position is used for fully occupied ventilation.
When demand controlled ventilation is not being used, the mini-
mum position potentiometer should be used to set the occupied
ventilation position. The maximum demand ventilation position
should be turned fully clockwise.
Adjust the minimum position potentiometer to allow the mini-
mum amount of outdoor air, as required by local codes, to enter
measured in the space or return air
2
800 ppm
900 ppm
1000 ppm
1100 ppm
5 6 7 8
the building. Make minimum position adjustments with at least
10°F temperature difference between the outdoor and return-air
temperatures.
To determine the minimum position setting, perform the following
procedure:
1. Calculate the appropriate mixed air temperature using the
following formula:
OA
(T x )
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
As an example, if local codes require 10% outdoor air during oc-
cupied conditions, outdoor-air temperature is 60°F, and return-air
temperature is 75°F.
(60 x 0.10) + (75 x 0.90) = 73.5°F
2. Disconnect the supply air sensor from terminals T and T1.
3. Ensure that the factory-installed jumper is in place across
terminals P and P1. If remote damper positioning is being
used, make sure that the terminals are wired according to
Fig. 58 and that the minimum position potentiometer is
turned fully clockwise.
4. Connect 24 vac across terminals TR and TR1.
5. Carefully adjust the minimum position potentiometer until
the measured mixed air temperature matches the calcu-
lated value.
6. Reconnect the supply air sensor to terminals T and T1.
Remote control of the EconoMi$er IV damper is desirable when
requiring additional temporary ventilation. If a field-supplied re-
mote potentiometer (Honeywell part number S963B1128) is
wired to the EconoMi$er IV controller, the minimum position of
the damper can be controlled from a remote location.
To control the minimum damper position remotely, remove the
factory-installed jumper on the P and P1 terminals on the
EconoMi$er IV controller. Wire the field-supplied potentiometer
to the P and P1 terminals on the EconoMi$er IV controller. (See
Fig. 66.)
DAMPER MOVEMENT
Damper movement from full open to full closed (or vice versa)
takes 2 1 / minutes.
2
THERMOSTATS
The EconoMi$er IV control works with conventional thermostats
that have a Y1 (cool stage 1), Y2 (cool stage 2), W1 (heat stage 1),
W2 (heat stage 2), and G (fan). The EconoMi$er IV control does
not support space temperature sensors. Connections are made at
the thermostat terminal connection board located in the main con-
trol box.
OCCUPANCY CONTROL
The factory default configuration for the EconoMi$er IV control
is occupied mode. Occupied status is provided by the black jump-
er from terminal TR to terminal N. When unoccupied mode is de-
sired, install a field-supplied timeclock function in place of the
jumper between TR and N. When the timeclock contacts are
closed, the EconoMi$er IV control will be in occupied mode.
When the timeclock contacts are open (removing the 24-v signal
from terminal N), the EconoMi$er IV will be in unoccupied
mode.
DEMAND CONTROLLED VENTILATION (DCV)
When using the EconoMi$er IV for demand controlled ventila-
tion, there are some equipment selection criteria which should be
considered. When selecting the heat capacity and cool capacity of
51
RA
+ (T x ) = T
R
100
M