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Outdoor
Dry Bulb Changeover
The standard
controller
is shipped
from the factory
configured
for
outdoor
dry bulb changeover
control.
The outdoor
air and mixed
air temperature
sensors
are included
as standard.
For this control
mode,
the outdoor
temperature
is compared
to an adjustable
set
point
selected
on the control.
If the outdoor-air
temperature
is
above the set point, the EconoMi$er
IV will adjust the outdoor-air
dampers
to minimum
position.
If the outdoor-air
temperature
is
below the set point, the position
of the outdoor-air
dampers
will be
controlled
to provided
free cooling
using outdoor
air. When in this
mode, the LED next to the free cooling
set point potentiometer
will
be on. The changeover
temperature
set point
is controlled
by the
free cooling
set point
potentiometer
located
on the control.
The
scale on the potentiometer
is A, B, C, and D. See Fig. 21 for the
corresponding
temperature
changeover
values.
Differential
Dry Bulb Control
For differential
dry bulb
control
the standard
outdoor
dry bulb
sensor is used in coniunction
with an additional
accessory
dry bulb
sensor
(part number
CRTEMPSN002A00).
The accessory
sensor
nmst be mounted
in the return airstream.
Wiring is provided
in the
EconoMiSer
IV wiring
harness.
(See Fig. 22.)
In this mode of operation,
the outdoor-air
temperature
is compared
to the return air temperature
and the lower temperature
airstream
is
used for cooling.
When
using
this mode
of changeover
control,
turn the enthalpy
set point
potentiometer
fully clockwise
to the D
setting.
Outdoor
Enthalpy
Changeover
For
enthalpy
control,
accessory
enthalpy
sensor
(part
number
HH57AC078)
is required.
Replace
the standard
outdoor
dry bulb
temperature
sensor with the accessory
enthalpy
sensor in the same
mounting
location.
When the outdoor
air enthalpy
rises above the
outdoor
enthalpy
changeover
set point,
the outdoor-air
damper
moves
to its minimum
position.
The outdoor
enthalpy
changeover
set point is set with the outdoor
enthalpy
set point potentiometer
on
the EconoMi$er
IV controller.
The set points
are A, B, C, and D.
(See Fig. 23.) The factory-installed
620-ohm
jumper
must be in
place across
ternfinals
SR and + on the EconoMi$er
IV controller.
(See Fig. 22.)
Differential
Enthalpy
Control
For differential
enthalpy
control,
the EconoMi$er
IV controller
uses
two
enthalpy
sensors
(HH57AC078
and
CRENTDIF004A00),
one in the outside
air and one in the return
air duct. The EconoMi$er
IV controller
compares
the outdoor
air
enthalpy
to the return
air enthalpy
to deternfine
EconoMi$er
IV
use.
The
controller
selects
the
lower
enthalpy
air
(return
or
outdoor)
for cooling.
For example,
when
the outdoor
air has a
lower
enthalpy
than
the return
air, the EconoMi$er
IV opens
to
bring in outdoor
air for free cooling.
Replace the standard outside air dry bulb temperature sensor with
the accessory enthalpy
sensor in the same mounting location.
Mount the return air enthalpy sensor in the return air duct. Wiring
is provided in the EconoMiSer
IV wiring harness. (See Fig. 22.)
The outdoor enthalpy changeover set point is set with the outdoor
enthalpy set point potentiometer on the EconoMi$er IV controller.
When using this mode of changeover control, turn the enthalpy set
point potentiometer fully clockwise to the D setting. (See Fig. 24.)
Indoor Air Quality (IAQ) Sensor Input
The IAQ input can be used for demand control ventilation control
based on the level of CO2 measured in the space or return air duct.
Mount
the optional
IAQ
sensor
according
to manufacturer
specifications.
The IAQ sensor should be wired to the AQ and
AQI
terminals
of the controller.
Adjust
the DCV (demand
controlled ventilation) potentiometers
to correspond
to the DCV
voltage
output
of
the
indoor
air
quality
sensor
at the
user-deternfined
set point. (See Fig. 25.)
If a separate field-supplied
transformer is used to power the IAQ
sensor, the sensor must not be grounded or the EconoMi$er
IV
control board will be damaged.
Exhaust Set Point Adjustment
The exhaust set point will deternfine when the exhaust fan runs
based on damper position (if accessory power exhaust is installed).
The set point is modified with the Exhaust Fan Set Point (EXH
SET) potentiometer. (See Fig. 24.) The set point represents the
damper position above which the exhaust fans will be turned on.
When there is a call for exhaust, the EconoMi$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.
Minimum Position Control
There is a minimum
damper
position
potentiometer
on the
EconoMi$er
IV controller. (See Fig. 24.) The nfininmm 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
compounds)
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. 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.
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