19
INDOOR AIR QUALITY (IAQ) SENSOR INPUT
The IAQ input can be used for demand control ventilation control
based on the level of CO
2
measured in the space or return air duct.
Mount the accessory IAQ sensor according to manufacturer
specifications. The IAQ sensor should be wired to the AQ and
AQ1 terminals of the controller. Adjust the DCV voltage output of
the indoor air quality sensor at the user-determined set point. (See
Fig. 43.)
If a separate field-supplied transformer is used to power the IAQ
sensor, the sensor must not be grounded or the EconoMi$er IV
control board will be damaged.
Fig. 42 — Return Air Temperature or Enthalpy Sensor
Mounting Location
EXHAUST SET POINT ADJUSTMENT
The exhaust set point will determine when the exhaust fan runs
based on damper position (if accessory power exhaust is installed).
The set point is modified with the Exhaust Fan Set Point (EXH
SET) potentiometer. (See Fig. 44.) The set point represents the
damper position above which the exhaust fans will be turned on.
When there is a call for exhaust, the EconoMi$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.
Fig. 43 — CO
2
Sensor Maximum Range Setting
MINIMUM POSITION CONTROL
There is a minimum damper position potentiometer on the
EconoMi$er IV controller. (See Fig. 44.) The minimum damper
position maintains the minimum airflow into the building during
the occupied period.
When using demand ventilation, the minimum damper position
represents the minimum ventilation position for VOC (volatile
organic compound) ventilation requirements. The maximum
demand ventilation position is used for fully occupied ventilation.
When demand ventilation control is not being used, the minimum
position potentiometer should be used to set the occupied
ventilation position. When not using a CO
2
sensor, the DCV MAX
potentiometer must be fully closed (CCW) for the Minimum
Position potentiometer to function correctly.
Adjust the minimum position potentiometer to allow the
minimum amount of outdoor air, as required by local codes, to
enter the building. Make minimum position adjustments with at
least 10°F temperature difference between the outdoor and
return-air temperatures.
To determine the minimum position setting perform the following
procedure:
1. Calculate the appropriate mixed air temperature using the
following formula:
T
O
= Outdoor-Air Temperature
OA = Percent of Outdoor Air
T
R
= Return-Air Temperature
RA = Percent of Return Air
T
M
= Mixed-Air Temperature
2. Disconnect the supply air sensor from terminals T and T1.
3. Ensure that the factory-installed jumper is in place across
terminals P and P1. If remote damper positioning is being
used, make sure that the terminals are wired according to
Fig. 15 and that the minimum position potentiometer is
turned fully clockwise.
4. Connect 24 vac across terminals TR and TR1.
5. Carefully adjust the minimum position potentiometer until
the measured mixed-air temperature matches the calculated
value.
6. Reconnect the supply air sensor to terminals T and T1.
Remote control of the EconoMi$er IV damper is desirable when
requiring additional temporary ventilation. If a field-supplied
remote potentiometer 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$er IV controller. (See
Fig. 15.)
DAMPER MOVEMENT
Damper movement from full open to full closed (or vice versa)
takes 2-1/2 minutes.
THERMOSTATS
The EconoMi$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
control box.
Return AiR
Sensor
Return Duct
(Field-provided)
0
1000
2000
3000
4000
5000
6000
2345678
RANGE CONFIGURATION (ppm)
DAMPER VOLTAGE FOR MAX VENTILATION RATE
CO SENSOR MAX RANGE SETTING
2
800 ppm
900 ppm
1000 ppm
1100 ppm
T
O
x OA + (T
R
x RA ) = T
M
100 100
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