Bryant 800SB Operating Instructions Manual page 41

800SB/801SB: Installation, Start–Up, Operating and Service and Maintenance Instructions
e. Blower-ON Delay – If the burner flame is proven, the blower
motor is turned on at HEAT speed 25 sec after the gas valve GV
is energized.
Simultaneously, the electronic air cleaner terminal EAC-1 is
energized and remains energized as long as the blower motor
BLWM is energized.
f. Heat-OFF Delay – When the thermostat is satisfied, the R-to-W
circuit is opened, de-energizing the gas valve GV, stopping gas
flow to the burners, and de-energizing the 24-V humidifier
terminal 24VAC HUM. The inducer motor IDM will remain ON
for a 5-second post-purge period. Then turn off the inducer motor
and HUM (115-V) humidifier terminal. The blower motor
BLWM and air cleaner terminal EAC 1 will remain energized for
90, 120, 150, or 180 seconds (depending on the HEAT-OFF delay
selection). The furnace control CPU is factory-set for a
120-second Heat-Off Delay.
2. Cooling Mode
(See Fig. 29 for thermostat connections.) The thermostat closes the
R-to-Y circuits. The R-to-Y circuit starts the outdoor unit, and the
R-to-Y circuits start the furnace blower motor BLWM on COOL
speed. The electronic air cleaner terminal EAC-1 is energized with
115 vac when the blower motor BLWM is operating. When the
thermostat is satisfied, the R-to-Y circuits are opened. The outdoor
unit will stop, and the furnace blower motor BLWM will continue
operating on the COOL speed for an additional 5, 30, or 90 seconds
(depending on the cooling blower-OFF delay selection). The
furnace CPU is factory set for a 90 second cooling blower-OFF
delay (see Fig. 28).
3. Continuous Fan Mode
When the R-to-G circuit is closed by the thermostat, the blower
motor BLWM will operate at the continuous-blower speed selected.
Terminal EAC-1 is energized as long as the blower motor BLWM is
ON.
During a call for heat, the blower BLWM will stop during igniter
warm-up (17 sec), ignition, and blower-ON delay (25 sec), allowing
the furnace heat exchangers to heat up more quickly, then restarts at
the end of the blower-ON delay period at HEAT speed.
When the thermostat "calls for cooling", the blower motor BLWM
will continue to operate at COOL speed. When the thermostat is
satisfied, the blower motor BLWM will continue to operate on
COOL speed based on the cooling blower-OFF delay setting before
reverting back to continuous fan speed.
When the R-to-G circuit is opened, the blower motor BLWM will
continue operating for an additional 5 sec, if no other function
requires blower motor BLWM operation.
4. Heat Pump
When installed with a heat pump, the furnace control automatically
changes the timing sequence to avoid long blower off times during
demand defrost cycles.
R-to-W-and-Y-and-G circuits are energized the furnace control
CPU will continue to turn on the blower motor BLWM at HEAT
speed, and begin a heating cycle. The blower motor BLWM will
remain on until the end of the prepurge period, then shut off for 24
sec then come back on at HEAT speed. When the W input signal
disappears, the furnace control begins a normal inducer post-purge
period and the blower switches to COOL speed after a 3 sec delay.
If the R-to-W-and-Y-and-G signals disappear at the same time, the
blower motor BLWM will remain on for the selected blower- OFF
delay period. If the R-to-W-and-Y signals disappear, leaving the G
signal, the blower motor BLWM will continue running the blower
motor at CONTINUOUS FAN speed after the selected heating
blower-OFF delay period is completed.
Wiring Diagram
Fig. 46 shows a schematic for the furnace wiring diagram.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
When the R-to-W-and-Y
Troubleshooting
Refer to the service label (see
Fig. 51) can be a useful tool in isolating furnace operation problems.
Beginning with the word "Start," answer each question and follow the
appropriate arrow to the next item. The Guide will help to identify the
problem or failed component. After replacing any component, verify
correct operation sequence.
or
41
Fig. 45). The Troubleshooting Guide (see