Economi$Er Iv Standard Sensors - Bryant Preferred 551J Service And Maintenance Instructions

EconoMi$er IV Standard Sensors

Table 9 provides a summary of EconoMi$er IV Logic. A function-
al view of the EconoMi$er is shown in Fig. 45. Typical settings,
sensor ranges, and jumper positions are also shown. An
EconoMi$er IV simulator program is available from Bryant to
help with EconoMi$er IV training and troubleshooting.
INPUTS
Demand
Controlled
Outdoor
Ventilation (DCV)
High (Free
Cooling LED off)
Below set
(DCV LED off)
Low (Free
Cooling LED on)
High (Free
Cooling LED off)
Above set
(DCV LED on)
Low (Free
Cooling LED on)
*For single enthalpy control, the module compares outdoor enthalpy to
the ABCD set point.
†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.
Table 9 — EconoMi$er IV Input/Output Logic
Enthalpy*
Y1 Y2
Return Stage 1 Stage 2
On On
Low On Off
Off Off
On On
High On Off
Off Off
On On
Low On Off
Off Off
On On
High On Off
Off Off
Fig. 45 — EconoMi$er IV Functional View
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$er IV system can be used for free cooling. The sensor is
factory-installed on the EconoMi$er IV in the outdoor airstream.
(See Fig. 46.) The operating range of temperature measurement is
40°F to 100°F (4°C to 38°C). See Fig. 47.
Compressor
Occupied
On On
On Off Minimum position
Off Off
On Off
Modulating** (between min.
position and full-open)
Off Off
Off Off Minimum position
On On
Modulating†† (between min.
On Off
position and DCV maximum)
Off Off
On Off
Off Off Modulating***
Off Off
*** 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).
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OUTPUTS
N Terminal†
Unoccupied
Damper
Closed
Modulating** (between closed
and full-open)
Closed
Modulating†† (between closed
and DCV maximum)
Modulating†††