Bryant DURAPAC 579F Installation, Start-Up And Service Instructions Manual page 16

LEGEND
DCV — Demand Controlled Ventilation
IAQ — Indoor Air Quality
LALS — Low Temperature Compressor
Lockout Switch
OAT — Outdoor-Air Temperature
POT — Potentiometer
C. EconoMi$erIV Control Modes
Determine the EconoMi$erIV control mode before set up of the
control. Some modes of operation may require different sensors.
Refer to Table 11. The EconoMi$erIV is supplied from the fac-
tory with a supply air temperature sensor, a low temperature
compressor lockout switch, and an outdoor air temperature
sensor. This allows for operation of the EconoMi$erIV with out-
door air dry bulb changeover control. Additional accessories
can be added to allow for different types of changeover control
and operation of the EconoMi$erIV and unit.
Outdoor Dry Bulb Changeover
The standard controller is shipped from the factory config-
ured for outdoor dry bulb changeover control. The outdoor
air and supply air temperature sensors are included as
standard. For this control mode, the outdoor temperature is
compared to an adjustable set point selected on the control.
If the outdoor-air temperature is above the set point, the
EconoMi$erIV will adjust the outdoor-air dampers to mini-
mum position. If the outdoor-air temperature is below the set
point, the position of the outdoor-air dampers will be con-
trolled to provide free cooling using outdoor air. When in this
mode, the LED next to the free cooling set point potentiome-
ter will be on. The changeover temperature set point is con-
trolled by the free cooling set point potentiometer located on
the control. See Fig. 27. The scale on the potentiometer is A,
B, C, and D. See Fig. 28 for the corresponding temperature
changeover values.
Potentiometer Default Settings:
Power Exhaust Middle
Minimum Pos. Fully Closed
DCV Max. Middle
DCV Set Middle
Enthalpy C Setting
Fig. 26 — EconoMi$erIV Wiring
— 16
NOTES:
1. 620 ohm, 1 watt 5% resistor should be removed only when using differential
enthalpy or dry bulb.
2. If a separate field-supplied 24 v transformer is used for the IAQ sensor power
supply, it cannot have the secondary of the transformer grounded.
3. For field-installed remote minimum position POT, remove black wire jumper
between P and P1 and set control minimum position POT to the minimum
position.
Differential Dry Bulb Control
For differential dry bulb control the standard outdoor dry
bulb sensor is used in conjunction with an additional acces-
sory return air sensor (part number CRTEMPSN002A00).
The accessory sensor must be mounted in the return
airstream. See Fig. 29.
In this mode of operation, the outdoor-air temperature is
compared to the return-air temperature and the lower tem-
perature airstream is used for cooling. When using this
mode of changeover control, turn the free cooling/enthalpy
set point potentiometer fully clockwise to the D setting. See
Fig. 27.
Outdoor Enthalpy Changeover
For enthalpy control, accessory enthalpy sensor (part num-
ber HH57AC078) is required. Replace the standard outdoor
dry bulb temperature sensor with the accessory enthalpy
sensor in the same mounting location. See Fig. 24. When the
outdoor air enthalpy rises above the outdoor enthalpy
changeover set point, the outdoor-air damper moves to its
minimum position. The outdoor enthalpy changeover set
point is set with the outdoor enthalpy set point potentiome-
ter on the EconoMi$erIV controller. The set points are A, B,
C, and D. See Fig. 30. The factory-installed 620-ohm jumper
must be in place across terminals SR and SR+ on the
EconoMi$erIV controller. See Fig. 26 and 31.
—