56
AIR CONDITIONING AIRFLOW 070 MODEL 090 MODEL 110, 135,
TONS (12,000 BTU/HR) (CFM) & 155 MODELS
1-1/2 525 X X
2 700 X X X
2-1/2 875 X X X
3 1050 X X X
3-1/2 1225 X X X
4 1400 X X
5 1750 X
6 2100 X
X-INDICATES AN ALLOWABLE SELECTION.
AIR CONDITIONING (A/C) OR CONTINUOUS-FAN (CF) AIRFLOW SELECTION CHART
BASED ON 350 CFM/TON
SW1-5 OFF
MODEL
SIZE
070 DEF 525
2
700 875 1050
1
1225 1225 1225
090 DEF 525 700
2
875 1050 1225 1400
1
1400
110,135,155 DEF 700 875
2
1050 1225 1400 1750
1
2100
Cooling Tonnage vs. Airflow (CFM)
2
1
2
1
1
2
SWITCH SW3 POSITIONS
1.DEFAULT A/C AIRFLOW WHEN A/C SWITCHES ARE IN OFF POSITION (FACTORY SETTING)
2.DEFAULT CONT. FAN AIRFLOW WHEN CF SWITCHES ARE IN OFF POSITION (FACTORY SETTING)
3. SWITCH POSITIONS ARE ALSO SHOWN ON FURNACE WIRING DIAGRAM
BASED ON 400 CFM/TON
SW1-5 OFF
MODEL
SIZE
070 DEF 600
2
800 1000 1200
1
1400 1400 1400
090 DEF 600 800
2
1000 1200 1400 1600
1
1600
110,135,155 DEF 800 1000
2
1200 1400 1600 2000
1
2200
SWITCH SW3 POSITIONS
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
OFF
321
A03220
Fig. 63 -- Cooling (A/C) or Continuous--Fan (CF) Airflow Selection Chart
prepurge period after the low-- heat pressure switch LPS closes. If
the high--heat pressure switch HPS fails to close and the low--heat
pressure switch LPS closes, the furnace will operate at low--heat
gas flow rate until the high--heat pressure switch closes for a
maximum of 2 minutes after ignition.
b. Igniter Warm--Up -- At the end of the prepurge period,
the Hot--Surface Igniter HSI is energized for a
17-- second igniter warm--up period.
c. Trial-- For--Ignition Sequence --When the igniter
warm-- up period is completed the main gas valve relay
contact GVR closes to energize the gas valve solenoid
GV--M. The gas valve solenoid GV--M permits gas
flow to the burners where it is ignited by the HSI. Five
seconds after the GVR closes, a 2 --second flame
proving period begins. The HSI igniter will remain
energized until the flame is sensed or until the
2-- second flame proving period begins. If the furnace
control CPU selects high--heat operation, the high--heat
gas valve solenoid GV -- HI is also energized.
d. Flame--Proving -- When the burner flame is proved at
the flame-- proving sensor electrode FSE, the inducer
motor IDM switches to low--speed unless the furnace
is operating in high --heat, and the furnace control CPU
begins the blower--ON delay period and continues to
hold the gas valve GV--M open. If the burner flame is
not proved within two seconds, the control CPU will
close the gas valve GV--M, and the control CPU will
repeat the ignition sequence for up to three more
Trials--For--Ignition before going to Ignition--Lockout.
Lockout will be reset automatically after three hours,
by momentarily interrupting 115 vac power to the
furnace, or by interrupting 24 vac power at SEC1 or
SEC2 to the furnace control CPU (not at W/W1, G, R,
etc.). If flame is proved when flame should not be
present, the furnace control CPU will lock out of
Gas-- Heating mode and operate the inducer motor
IDM on high speed until flame is no longer proved.
e. Blower--On delay -- If the burner flame is proven the
blower--ON delays for low--heat and high--heat are as
315A
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