Bryant 548J Service And Maintenance Instructions page 49

INPUTS
Demand Control
Ventilation (DCV)
Outdoor
(Free Cooling LED Off)
Below set
(DCV LED Off)
(Free Cooling LED On)
(Free Cooling LED Off)
Above set
(DCV LED On)
(Free Cooling LED On)
* For single enthalpy control, the module compares outdoor enthalpy to the ABCD setpoint.
† Power at N terminal determines Occupied/Unoccupied setting: 24 vac (Occupied), no power (Unoccupied).
** Modulation is based on the supply-air sensor signal.
†† Modulation is based on the DCV signal.
*** Modulation is based on the greater of DCV and supply-air sensor signals, between minimum position and either maximum position (DCV)
or fully open (supply-air signal).
††† Modulation is based on the greater of DCV and supply-air sensor signals, between closed and either maximum position (DCV) or fully
open (supply-air signal).
EconoMi$er IV
Table 21 provides a summary of EconoMi$er IV.
Troubleshooting instructions are enclosed.
A functional view of the EconoMi$er is shown in Fig. 70.
Typical settings, sensor ranges, and jumper positions are
also shown.
EconoMi$er IV Standard Sensors
Outdoor Air Temperature (OAT) Sensor
The outdoor air temperature sensor (HH57AC074) is a 10
to 20 mA device used to measure the outdoor-air
Table 21 – EconoMi$er IV Input/Output Logic
Enthalpy*
Y1
Return
On
High
Low On
Off
On
Low
High On
Off
On
High
Low On
Off
On
Low
High On
Off
Fig. 70 - - EconoMi$er IV Functional View
Compressor
Y2 Occupied
Stage Stage
1 2
On On On
Off On Off Minimum position
Off Off Off
On On Off
Modulating** (between min.
position and full-open)
Off Off Off
Off Off Off Minimum position
On On On
Modulating†† (between min.
Off On Off position and DCV
maximum)
Off Off Off
On On Off
Off Off Off Modulating***
Off Off Off
temperature. The outdoor-air temperature is used to
determine when the EconoMi$er IV can be used for free
cooling. The sensor
EconoMi$er IV in the outdoor airstream. (See Fig. 66.)
The operating range of temperature measurement is 40_ to
100_F (4_ to 38_C). See Fig. 73.
Supply Air Temperature (SAT) Sensor
The supply air temperature sensor is a 3 K thermistor
located at the inlet of the indoor fan. (See Fig. 71.) This
sensor is factory installed. The operating range of
temperature measurement is 0° to 158_F (- - 18_ to 70_C).
See Table 15 for sensor temperature/resistance values.
49
OUTPUTS
N Terminal†
Unoccupied
Damper
Closed
Modulating** (between
closed and full-open)
Closed
Modulating†† (between
closed and DCV
maximum)
Modulating†††
is factory-installed
C06053
on the