Sequence Of Operation - Bryant LEGACY 582K Product Data

Sequence of operation

General
The sequence below describes the sequence of operation for an
electro-mechanical unit with and without a factory-installed
EconoMi$er ® IV (W7212 controller) and X (W7220 control-
ler). For information regarding a direct digital controller, see
the start-up, operations, and troubleshooting manual for the
applicable controller.
Electro-mechanical units with no economizer
Cooling (single stage units)
When the thermostat calls for cooling, terminals G and Y1 are
energized. The indoor fan will run at the user set fan speed and
the compressor contactor (CC) is energized causing the com-
pressor and outdoor fan to run.
When the thermostat removes the call for Y1, the compressor
contactor will de-energize shutting down the compressor and
the outdoor fan. When the thermostat removes the call for G,
the indoor fan will turn off after the specific unit fan off delay.
Cooling (two stage units)
When the thermostat calls for cooling, terminals G and Y1 are
energized. The indoor fan will run at the low fan speed and the
compressor contactor (CC) is energized causing the compres-
sor and outdoor fan to run. The low indoor fan speed is 66% of
the user set fan speed and the compressor will run at partial
capacity.
If additional cooling is needed, the thermostat will add the call
for Y2. This will increase the indoor fan speed to the user set
fan speed and energize the compressor loader for full compres-
sor capacity. The outdoor fan is the same speed for Y1 and Y2.
When the thermostat removes the call for Y2 but leaves the Y1,
the indoor fan will reduce speed to 66% of the user set fan
speed, the compressor loader will turn off, and the outdoor fan
will remain on. When the thermostat removes the call for Y1
the compressor contactor will de-energize shutting down the
compressor and the outdoor fan. When the thermostat removes
the call for G, the indoor fan will turn off after the specific unit
fan off delay.
NOTE: Per ASHRAE 90.1-2016 and IECC-2018 standards,
during the first stage of cooling operation the Unit Control
Board (UCB) will adjust the fan motor speed to provide 66% of
the total cfm established for the unit.
Gas heating (582K units)
NOTE: Legacy™ Line units have either 1 or 2 stages of gas
heat.
When the thermostat calls for heating, power is sent to W on
the Integrated Gas Controller (IGC) board. An LED (light-
emitting diode) on the IGC board turns on and remains on
during normal operation. A check is made to ensure that the
roll-out switch and limit switch are closed. If the check was
successful, the induced-draft motor is energized, and when its
speed is satisfactory, as proven by the flue gas pressure switch,
the ignition activation period begins. The burners will ignite
within 5 seconds. If the burners do not light, there is a 22 sec-
ond delay before another 5 second attempt. This sequence is
repeated for 15 minutes or until the burners light. If, after the
15 minutes, the burners still have not lit, heating is locked out.
To reset the control, break 24 V power to the thermostat.
130
When ignition occurs, the IGC board will continue to monitor
the condition of the roll-out switch, the limit switches, the flue
gas pressure switch, as well as the flame sensor. 45 seconds
after ignition occurs, assuming the unit is controlled through a
room thermostat set for fan auto, the indoor-fan motor will
energize (and the outdoor-air dampers will open to their mini-
mum position). If, for some reason, the over-temperature limit
opens prior to the start of the indoor fan blower, the unit will
shorten the 45 second delay to 5 seconds less than the time
from initiation of heat to when the limit tripped. Gas will not be
interrupted to the burners and heating will continue. Once the
fan-on delay has been modified, it will not change back to 45
seconds until power is reset to the control. On units with
2 stages of heat, when additional heat is required, W2 closes
and initiates power to the second stage of the main gas valve.
When the thermostat is satisfied, W1 and W2 open and the gas
valve closes, interrupting the flow of gas to the main burners. If
the unit is controlled through a room thermostat set for fan
auto, the indoor-fan motor will continue to operate for an addi-
tional 45 seconds then stop. A LED indicator is provided on the
IGC to monitor operation.
Electric heating (559K units)
NOTE: 559K units are sold as cooling only. If electric heaters
are required, use only factory-approved heaters. They will
operate as follows.
Units have either 1 or 2 stages of electric heat. When the ther-
mostat calls for heating, power is applied to G and the W1 ter-
minals at the unit. The unit control will energize the indoor fan
contactor and the first stage of electric heat. On units with two-
stage heating, when additional heating is required, the second
stage of electric heat (if equipped) will be energized when
power is applied at the W2 terminal on the unit.
IMPORTANT: The thermostat must be configured for Elec-
tric Heat so it will energize G with the W1 call.
Electro-mechanical units with factory-installed
EconoMi$er
When free cooling is not available, the compressors will be
controlled by the zone thermostat. When free cooling is avail-
able, the outdoor-air damper is modulated by the EconoMi$er
IV and X control to provide a 50°F (10°C) to 55°F (13°C)
mixed-air temperature into the zone. As the mixed air tempera-
ture fluctuates above 55°F (13°C) or below 50°F (10°C) damp-
ers will be modulated (open or close) to bring the mixed-air
temperature back within control. If mechanical cooling is uti-
lized with free cooling, the outdoor-air damper will maintain its
current position at the time the compressor is started. If the
increase in cooling capacity causes the mixed-air temperature
to drop below 45°F (7°C), then the outdoor-air damper position
will be decreased to the minimum position. If the mixed-air
temperature continues to fall, the outdoor-air damper will
close. Control returns to normal once the mixed-air tempera-
ture rises above 48°F (9°C). The power exhaust fans will be
energized and de-energized, if installed, as the outdoor-air
damper opens and closes.
If field-installed accessory CO
EconoMi$er IV and X control, a demand controlled ventilation
strategy will begin to operate. As the CO
increases above the CO set-point, the minimum position of the
2
sensors are connected to the
2
level in the zone
2