Product Overview

BAC-1xx36/1xxx36 Series (3 Relays and 6 Analog Outputs) Section 63 Application Guide S
Economizer Control
If the economizer option is enabled, the economizer mode is determined
by comparing outside air temperature (OAT) to the economizer enable
temperature. The economizer mode is enabled if the OAT is 1.0° F (0.56°
C) below the economizer enable temperature and disabled if the OAT is
1.0° F (0.56° C) above the econ enable temp.
If the application is congured for econ enable/disable, the economizer
mode is determined as above. Any time the econ mode is enabled, the
econ output is energized at 100% (12vdc). If the econ mode is disabled,
the econ output is deenergized.
If the application is congured for modulating operation, the following
sequence is used:
During occupied mode, if the economizer mode is enabled, the OA
damper will open to the greater of the minimum damper position set-
ting (adjustable, for ventilation) or the mixed air temperature PI loop.
The mixed air temp loop will modulate from 0% to 100% as the mixed
air temp rises above the mixed air temp setpoint.
During occupied mode, the mixed air temp setpoint is determined based
on a reset schedule. If the space temperature is at or below the active
cooling setpoint, the mixed air temp setpoint is 68.0° F (20.0° C). If the
space temperature is 2.0° F (1.1° C) above the active cooling setpoint, the
mixed air temp setpoint will be 53.0° F (11.7° C). The mixed air setpoint
will vary linearly in between.
During unoccupied mode, if the space temp exceeds the cooling setback
setpoint by cooling proportional band and the econ mode is enabled,
the OA damper shall open as called for by the mixed air temp loop. The
OA damper shall modulate to maintain 53.0° F (11.7° C) until the space
temp reaches the cooling setback setpoint at which point it shall close. If
at any time during unoccupied mode the economizer mode is disabled
based on OAT, the outside air damper will close.
If the system mode is set to “heating” during occupied mode, the
damper will open to minimum position when the fan is on. If the system
mode is set to “heating” during unoccupied mode or is set to “o” in
any occupancy mode, the outside damper will close. If at any time there
is a fan alarm, the OA damper shall shut.
If the mixed air temp drops below the low limit alarm temp, a low limit
alarm is generated and the outside air damper will close. Other safety
actions are taken and described in their respective sections of the se-
quence.
Dehumidification
If the dehumidication sequence is enabled on models BAC-
10136C/11136C, the dehumidication mode is started and stopped as
described in the Common Features section. Upon activation of the dehu-
midication mode, the cooling valve is opened 100%. The heating valve
then reheats the space as called for in a modied heating sequence to
maintain the active cooling setpoint. Upon termination of the dehumidi-
cation mode, the valves return to their normal sequence.