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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 modi-
fied with the Exhaust Fan Set Point (EXH SET) potentiometer.
See Fig. 32. 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$er IV controller provides a 45 ± 15
second delay before exhaust fan activation to allow the damp-
ers to open. This delay allows the damper to reach the appro-
priate position to avoid unnecessary fan overload.
Minimum Position Control
— There is a minimum damper
position potentiometer on the EconoMi$er IV controller. See
Fig. 32. The minimum damper position maintains the mini-
mum airflow into the building during the occupied period.
When using demand ventilation, the minimum damper po-
sition represents the minimum ventilation position for VOC
(volatile organic compound) ventilation requirements. The
maximum demand ventilation position is used for fully occu-
pied ventilation.
When demand ventilation control is not being used, the
minimum position potentiometer should be used to set the oc-
cupied ventilation position. The maximum demand ventilation
position should be turned fully clockwise.
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
As an example, if local codes require 10% outdoor air
during occupied conditions, outdoor-air temperature is
60 F, and return-air temperature is 75 F.
(60 x .10) + (75 x .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. 26 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$er IV damper is desirable
when requiring additional temporary ventilation. If a
field-supplied remote potentiometer (Honeywell part number
S963B1128) is wired to the EconoMi$er IV controller, the
minimum position of the damper can be controlled from a re-
mote location.
To control the minimum damper position remotely, remove
the factory-installed jumper on the P and P1 terminals on the
EconoMi$er IV controller. Wire the field-supplied potentiome-
ter to the P and P1 terminals on the EconoMi$er IV controller.
See Fig. 36.
Damper Movement
— Damper movement from full open to
full closed (or vice versa) takes 2
1
/
2
minutes.
Thermostats
— The EconoMi$er IV control works with con-
ventional thermostats that have a Y1 (cool stage 1), Y2 (cool
stage 2), W1 (heat stage 1), W2 (heat stage 2), and G (fan). The
EconoMi$er IV control does not support space temperature
sensors. Connections are made at the thermostat terminal con-
nection board located in the main control box.
Occupancy Control
— The factory default configuration for
the EconoMi$er IV control is occupied mode. Occupied status
is provided by the black jumper from terminal TR to terminal
N. When unoccupied mode is desired, install a field-supplied
timeclock function in place of the jumper between TR and N.
See Fig. 26. When the timeclock contacts are closed, the
EconoMi$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 ventilation, there are
some equipment selection criteria which should be considered.
When selecting the heat capacity and cool capacity of 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 outside air design criteria.
A proportional anticipatory strategy should be taken with
the following conditions: a zone with a large area, varied occu-
pancy, and equipment that cannot exceed the required ventila-
tion rate at design conditions. Exceeding the required ventila-
tion 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 supplied to increase as the room CO
2
level increases even though the CO
2
set point has not been
reached. By the time the CO
2
level reaches the set point, the
damper will be at maximum ventilation and should maintain
the set point.
In order to have the CO
2
sensor control the economizer
damper in this manner, first determine the damper voltage out-
put for minimum or base ventilation. Base ventilation is the
ventilation required to remove contaminants during unoccu-
pied 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 outside 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 mini-
mum damper position potentiometer to the correct position.
The same equation can be used to determine the occupied or
maximum ventilation rate to the building. For example, an out-
put of 3.6 volts to the actuator provides a base ventilation rate
of 5% and an output of 6.7 volts provides the maximum venti-
lation rate of 20% (or base plus 15 cfm per person). Use Fig. 37
to determine the maximum setting of the CO
2
sensor. For ex-
ample, a 1100 ppm set point relates to a 15 cfm per person de-
sign. Use the 1100 ppm curve on Fig. 37 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
(T
O
x
OA
)+(TRx
RA
)=T
M
100 100
(T
O
x
OA
)+(TRx
RA
)=T
M
100 100