Troubleshooting: Heating Sequence Of Operation - Lennox SIGNATURE SLP99UHV070XV36B Installation Instructions Manual

Troubleshooting: Heating Sequence of Operation

1
Safety
Check
Verify There
Is No Main Burner
Flame
Limit
Switch
Closed?
YES
Rollout
Circuit
Closed?
L
I
G
YES
H
T
O
Low
F
Pressure
F
Switch
Open?
YES
Combustion Air
Inducer ON at 70%
Rate Speed
Low
Pressure Switch
Closed Within 150
Seconds?
YES
Pre-Purge
15 Seconds
Ignitor ON
20 Seconds
Gas Valve
C
Energized
A
L
L
Ignition Trial Begins
F
(Ignitor ON)
O
R
1
S
Flame
T
Sensed Within
S
4 seconds?
T
A
G
E YES
H
E
Ignitor OFF
A
T
Wait For Ignition
Stabilization Delay
Set Target Firing Rate
Based on Thermostat
Signals Present
OR
2
Call For 2nd Stage Heat Call For Heat Satisfied
IGNITION AND CALL FOR LOW FIRE WITH TWO-STAGE
Combustion Air
De-Energize
NO Inducer On
Gas Valve
(100% rate
speed)
Combustion
Air Inducer
On (100%
rate speed)
De-Energize
NO
Gas Valve
Indoor Blower
ON (70%)
Error Code Flashes
NO
After 5 Seconds
Low Pressure
Switch Opens
Pressure Switch Calibration
NO
Calibration Successful?
5 minutes
(15 Seconds)
Indoor Blower Delay
Timer Started
Gas Valve
De-energized
NO
Ignitor OFF
3A
THERMOSTAT
After
Indoor blower OFF
Heat OFF Delay
(Low Heat Speed)
Error Code Indoor Blower
Flashes
ON (100%)
Error Code
Flashes
Closes?
NO
High
Pressure
Error Code Flashes
NO
Switch
After 5 Seconds
Open?
High Pressure
Switch Opens
YES
YES
4
Calibrations
NO YES
Attempted?
NO
Wait
Interpurge
NO
5th
Post-Purge
Unsuccessful YES
(20Seconds)
Trial?
SOFT LOCKOU T IS RESE T AUTOMATICALLY AFTER ONE HOUR WITH A CALL FOR HE AT ACTIVE,
1
OR BY CYCLING THE CALL FOR HE AT, OR BY CYCLING POWER TO THE CONTROL.
HARD LOCKOU T IS RESE T BY CYCLING POWER TO THE CONTROL.
2
Page 64
YES
Limit
NO
Closes Within 3
Minutes?
Indoor Blower OFF
After Heat OFF Delay
(High Heat Speed)
Soft Lockout:
Rollout
YES
Error Code
Circuit
Flashes
Combustion Air
Inducer OFF
After Post-Purge
Indoor Blower OFF After
Heat OFF Delay
Hard Lockout:
Error Code
2 2
Flashes
flashes
Call
For
NO
Heat?
YES
Soft Lockout:
Error Code
Flashes
Soft Lockout:
Combustion
Error Code
Air Inducer
Flashes
OFF
1
NO
Call For
Heat
Ends?
YES
Indoor
Blower
ON?
YES NO
Indoor blower OFF
After Heat OFF Delay
1
1