Ignition And Call For Low Fire With Single-Stage Thermostat - Lennox G71MPP SERIES Unit Information

IGNITION AND CALL FOR LOW FIRE WITH SINGLE−STAGE THERMOSTAT
4
Safety
Check
Verify There
Is No Main Burner
Flame
Limit
NO
Switch
Closed?
YES
Rollout
NO
Circuit
Closed?
L
I
G
YES
H
T
O
Low
F
Pressure
NO
F
Switch
Open?
YES
Combustion Air Inducer ON at
Ignition at 70% rate speed
Low
Pressure Switch
NO
Closed Within 150
Seconds?
YES
Pre−Purge
15 Seconds
Ignitor ON
20 Seconds
Gas Valve
Energized
Ignition Trial Begins
Indoor Blower On
C
Ignitor ON Delay Timer Started
A
L
L
F
Flame
O
Sensed Within NO
R
4 seconds?
H
E
A
T
YES
Ignitor OFF
Wait For Ignition
Stabilization Delay
Set to
Low Firing Rate
Move to Mid Firing Rate
and High Firing Rate after
2nd and 3rd Stage Delays
(based on DI P Switch selections)
Indoor Blower OFF After
Heat OFF Delay
(Low Heat Speed)
De−Energize
Combustion Air
Gas Valve
Inducer ON
(100%)
Combustion Air
Inducer ON
(100%)
De−Energize
Gas Valve
Indoor Blower
ON
(70%)
High
Error Code Flashes
Pressure
After 5 Seconds Switch
Open?
Low Pressure
Switch Opens
YES
YES
Pressure Switch Calibration
NO
Calibration Successful?
Wait
5 minutes
Interpurge
(15 Seconds)
NO
Gas Valve
De−energized 5th
Unsuccessful
Trial?
Ignitor OFF
1
SOF T LOCKOUT IS RESE T AUTOMATICAL LY AFTER ONE HOUR WITH A CALL FOR HEAT ACTIVE,
OR BY CYCLINGTHE CAL L FOR HEAT, OR BY CYCLING POWER TO THE CONTROL.
2 HARD LOCKOU T IS RESE T BY CYCLING POWER TO THE CONTROL.
Call For Heat Satisfied
3B
Page 59
YES
Indoor Blower
Error Code ON
Closes Within 3
Flashes
(100% Speed)
Rollout
Error Code
Circuit
Flashes
Closes?
NO
Combustion Air Inducer
OFF After Post−Purge
Indoor Blower OFF After
Error Code Flashes
NO
After 5 Seconds Heat OFF Delay
High Pressure
Hard Lockout:
Switch Opens
Error Code
4
Soft Lockout:
Calibrations
YES Error Code
Attempted?
Flashes
NO
Post−Purge Combustion Air
YES
(20 Seconds)
Inducer OFF
Limit
NO
Minutes?
Indoor Blower OFF
After Heat OFF Delay
(High Heat Speed)
Soft Lockout:
Error Code
1
Flashes
YES
2
Flashes
flashes
Call
For NO
Heat?
NO
YES
Call For
Heat
Ends?
YES
Indoor
Blower On?
YES
Indoor Blower OFF
After Heat OFF Delay
1
Soft Lockout:
Error Code
1
Flashes
NO