Bryant DuraPac 558F Installation & Service Instructions Manual page 16

F. Mechanical Cooling Lockout
Determine the outdoor-air temperature at which the
mechanical cooling (compressors) will be disabled. Locate the
mechanical cooling lockout (MECH CLG LOCKOUT) poten-
tiometer. To disable this feature, turn the potentiometer
counterclockwise (CCW) to the OFF position. Otherwise, set
the value between 10 and 60 F. Mechanical cooling will not
operate when the outdoor air temperature is below this
value. See Fig. 17.
G. Dry Bulb Changeover Set Up
Determine the dry bulb changeover set point from Table 5.
The settings are A, B, C and D. Locate the ECON SP potenti-
ometer and set the dry bulb changeover set point. See
ECONOMI$ER SWITCHOVER STRATEGY
Dry Bulb
Single Enthalpy
Differential Temperature
Differential Enthalpy*
*Must be selected manually.
Table 5 — Changeover Set Points
SETTINGS
Dry Bulb (°F)
Single Enthalpy* (Btu/lb)
Differential Temperature*
(°F, Not Adjustable)
Differential Enthalpy*
(Btu/lb, Not Adjustable)
*Field-installed accessory.
CLG — Cooling
COM — Common
DAT — Discharge Air Thermistor
DM — Damper Motor
GND — Ground
LED — Light-Emitting Diode
*OAT sensor shipped with economizer option. OAH, RAT, RAH and CO
Table 4 — EconoMi$er Switchover Control Strategy
Outdoor Air Temperature
X
X
A B C D
73 69 66 63
27 25 24 22
2 2 2 2
1 1 1 1
LEGEND
OAH — Outdoor-Air Enthalpy Sensor
OAT — Outdoor-Air Temperature Sensor
POT — Potentiometer
RAH — Return-Air Enthalpy Sensor
RAT — Return-Air Temperature Sensor
REM — Remote
are field-installed accessories.
2
Fig. 24 — Typical EconoMi$er Sensor Wiring
— 16
Fig. 17. When the OAT is above this set point, the damper is
limited to minimum position setting.
If a potentiometer fails, its setting will default to the values
in Table 6.
H. Ventilation Air (Minimum Position Set Up)
If ventilation air is not required, skip this section. If ventila-
tion air is required, perform the following:
1. The indoor fan must be on to set the ventilation air.
Either put the thermostat in the continuous fan mode
or jumper the R and G terminals at the rooftop unit
connection board.
SENSORS REQUIRED
Outdoor Air Enthalpy Return Air Temperature
X
X
Table 6 — Default Potentiometer Settings
POTENTIOMETER
CO SP (PPM)
2
MECH CLG LOCKOUT
ECON SP
MIN POS (%)
—
Return Air Enthalpy
X
X
DEFAULT SETTING
1,000
50 F
D
20