Lennox SIGNATURE SLP99DFV User Manual

Page 62
Troubleshooting: Heating Sequence of Operation
IGNITION AND CALL FOR LOW FIRE WITH TWO-STAGE
THERMOSTAT
Call For 2nd Stage Heat Call For Heat Satisfied
Limit
Switch
Closed?
Limit
Closes Within 3
Minutes?
NO
Soft Lockout:
Error Code
Flashes
flashes
YES
Rollout
Circuit
Closed?
Low
Pressure
Switch
Open?
Low
Pressure Switch
Closed Within 150
Seconds?
High
Pressure
Switch
Open?
YES
NO
NO
NO
NO
YES
NO
De-Energize
GasValve
De-Energize
GasValve
Error Code
Flashes
Error Code
Flashes
Rollout
Circuit
Closes?
Hard Lockout:
Error Code
Flashes
Error Code Flashes
After 5 Seconds
Error Code Flashes
After 5 Seconds
L
I
G
H
T
O
F
F
Safety
Check
After
(Low Heat Speed)
Verify There
Is No Main Burner
Flame
YES
YES
Low Pressure
Switch Opens
High Pressure
Switch Opens
YES
NO
Pressure Switch
Calibration
Pre-Purge
15 Seconds
YES
GasValve
Energized
Flame
Sensed Within
4 seconds?
GasValve
De-energized
Interpurge
(15 Seconds)
5th
Unsuccessful
Trial?
Wait For Ignition
Stabilization Delay
Post-Purge
(20Seconds)
Soft Lockout:
Error Code
Flashes
YES
NO
NO
YES
Call For
Heat
Ends?
NO
YES
YES NO
C
A
L
L
F
O
R
1
S
T
S
T
A
G
E
H
E
A
T
3A2
1
1
OR
Call
For
Heat?
NO
4
Calibrations
Attempted?
Calibration
Successful?
Wait
5 minutes
NO
NO
Soft Lockout:
Error Code
Flashes
YES
YES
YES
2
1
1
2
SetTarget Firing Rate
Based on Thermostat
Signals Present
SOFT LOCKOUT IS RESET AUTOMATICALLY AFTER ONE HOUR WITH A CALL FOR HEAT ACTIVE,
OR BY CYCLING THE CALL FOR HEAT, OR BY CYCLING POWER TO THE CONTROL.
HARD LOCKOUT IS RESET BY CYCLING POWER TO THE CONTROL.
1
2
Indoor blower OFF
Combustion Air
Inducer On
(100% rate
speed)
Indoor Blower
ON (100%)
Heat OFF Delay
Indoor Blower OFF
After Heat OFF Delay
(High Heat Speed)
Combustion
Air Inducer
On (100%
rate speed)
Indoor Blower
ON (70%)
Combustion Air
Inducer OFF
After Post-Purge
Indoor Blower OFF After
Heat OFF Delay
Combustion Air
Inducer ON at 70%
Rate Speed
Ignitor ON
20 Seconds
Indoor
Blower
ON?
Indoor blower OFF
After Heat OFF Delay
Indoor Blower Delay
Timer Started
Ignition Trial Begins
(Ignitor ON)
Ignitor OFF
Ignitor OFF
Combustion
Air Inducer
OFF

Lennox SIGNATURE SLP99DFV Specifications

General

Brand	Lennox
Model	SIGNATURE SLP99DFV
Category	Furnace
Language	English