Bryant 574D----A, Руководство по установке

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6000
5000
4000
3000
2000
1000
0
2 3 4 5 6 7 8
800 ppm
900 ppm
1000 ppm
1100 ppm
A09713
Fig. 43 -- CO
2
Sensor Maximum Range Setting
TR TR1
24
Vac
HOT
24 Vac
COM
1 2
5
4 3
EF1 EF
C
10V
DCV
DCV
Max
DCV
D A
B
Set
2V
10V
10V
Min
Pos
2V
2V
Free
Cool
SR
SO
SO+
AQ+
T1
T
P
P1
N1
N
AQ
SR+
Open
EXH
Set
EXH
A09712
Fig. 44 -- Economizer Controller
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 Economizer
controller. The set points are A, B, C, and D. See Fig. 42. The
factory--installed 620--ohm jumper must be in place across terminals
SR and SR+ on the Economizer controller. See Fig. 44 and Fig. 45.
DIFFERENTIAL ENTHALPY CONTROL — For differential
enthalpy control, the Economizer controller uses two enthalpy
sensors (HH57AC078 and CRENTDIF004A00), one in the outside
air and one in the return airstream. The Economizer controller
compares the outdoor air enthalpy to the return air enthalpy to
determine Economizer 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 and is below the set point, the
Economizer 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. See Fig. 41. When using this
mode of changeover control, turn the enthalpy set point poten-
tiometer fully clockwise to the D setting.
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 potentiometers to correspond to 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
Economizer control board will be damaged.
EXHAUST SET POINT ADJUSTMENT— The exhaust set point
will determine when the exhaust fan runs based on damper position
(if power exhaust is installed). The set point is modified with the
Exhaust Fan Set Point (EXH SET) potentiometer. See Fig. 45 for
Wiring Diagram. The set point represents the damper position above
which the exhaust fans will be turned on. When there is a call for
exhaust, the Economizer 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 Economizer controller. See
Fig. 39 and Fig. 45. 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 DCV Max potentiometer
must be fully closed (CCW) to allow the minimum position
potentiometer to function correctly.
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 (12.2
_
C) 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
x OA/100) + (T
R
x RA/100) = T
M
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 (15.6
_
C), and return--air temperature is 75
_
F
(23.9
_
C). (60 x .10) + (75 x .90) = 73.5
_
F (23.1
_
C)
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. 45 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 Economizer damper is desirable when
requiring additional temporary ventilation. If a field--supplied
remote potentiometer (Honeywell part number S963B1128) is
wired to the Economizer 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 Economizer controller.
Wire the field--supplied potentiometer to the P and P1 terminals on
the Economizer controller. See Fig. 44 and Fig. 45.
574D
--
--
A