Bryant 548J - Manual (Page 49)

49
Table 21 – EconoMi$er IV Input/Output Logic
INPUTS OUTPUTS
Demand Control
Ventilation (DCV)
Enthalpy*
Y1 Y2
Compressor N Terminal†
Outdoor Return
Stage
1
Stage
2
Occupied Unoccupied
Damper
Below set
(DCV LED Off)
High
(Free Cooling LED Off)
Low
On On On On
Minimum position Closed On Off On Off
Off Off Off Off
Low
(Free Cooling LED On)
High
On On On Off Modulating** (between min.
position and full-open)
Modulating** (between
closed and full-open) On Off Off Off
Off Off Off Off Minimum position Closed
Above set
(DCV LED On)
High
(Free Cooling LED Off)
Low
On On On On Modulating†† (between min.
position and DCV
maximum)
Modulating†† (between
closed and DCV
maximum)
On Off On Off
Off Off Off Off
Low
(Free Cooling LED On)
High
On On On Off
Modulating*** Modulating††† On Off Off Off
Off Off Off Off
* For single enthalpy control, the module compares outdoor enthalpy to the ABCD setpoint.
† Power at N terminal determines Occupied/Unoccupied setting: 24 vac (Occupied), no power (Unoccupied).
** Modulation is based on the supply-air sensor signal.
†† Modulation is based on the DCV signal.
*** Modulation is based on the greater of DCV and supply-air sensor signals, between minimum position and either maximum position (DCV)
or fully open (supply-air signal).
††† Modulation is based on the greater of DCV and supply-air sensor signals, between closed and either maximum position (DCV) or fully
open (supply-air signal).
C06053
Fig. 70 -- EconoMi$er IV Functional View
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
temperature. The outdoor-air temperature is used to
determine when the EconoMi$er IV can be used for free
cooling. The sensor is factory-installed on the
EconoMi$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.
548J