508146-01
Issue 2051
Page
68
of 7
0
Figure 57. Ignition and Call for Low Fire with Single-Stage Thermostat
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
Gas Valve
De−Energize
Gas Valve
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
Verify There
Is No Main Burner
Flame
YES
YES
Low Pressure
Switch Opens
High Pressure
Switch Opens
YES
NO
Pre−Purge
15 Seconds
YES
Gas Valve
Energized
Ignition Trial Begins
Flame
Sensed Within
4 seconds?
Gas Valve
De−energized
Interpurge
(15 Seconds)
5th
Unsuccessful
Trial?
Wait For Ignition
Stabilization Delay
Post−Purge
(20 Seconds)
Soft Lockout:
Error Code
Flashes
YES
NO
NO
YES
Call For
Heat
Ends?
NO
YES
YES
NO
C
A
L
L
F
O
R
H
E
A
T
3B
1
4
Move to Mid Firing Rate
and High Firing Rate after
2nd and 3rd Stage Delays
(based on DI P Switch selections)
Pressure Switch
Calibration
Call
For
Heat?
NO
4
Calibrations
Attempted?
Calibration
Successful?
Wait
5 minutes
NO
NO
Soft Lockout:
Error Code
Flashes
YES
YES
YES
SOFT LOCKOUT IS RESE T AUTOMATICALLY AFTER ONE HOUR WITH A CALL FOR HEAT ACTIVE,
OR BY CYCLINGTHE CALL FOR HEAT, OR BY CYCLING POWER TO THE CONTROL.
HARD LOCKOUT IS RESE T BY CYCLING POWER TO THE CONTROL.
1
2
1
2
1
Set to
Low Firing Rate
Indoor Blower OFF After
Heat OFF Delay
(Low Heat Speed)
Combustion Air
Inducer ON
(100%)
Indoor Blower
ON
(100% Speed)
Indoor Blower OFF
After Heat OFF Delay
(High Heat Speed)
Combustion Air
Inducer ON
(100%)
Indoor Blower
ON
(70%)
Combustion Air Inducer
OFF After Post-Purge
Indoor Blower OFF After
Heat OFF Delay
Combustion Air Inducer ON at
Ignition at 70% rate speed
Indoor
Blower On?
Indoor Blower OFF
After Heat OFF Delay
Ignitor ON
20 Seconds
Ignitor ON
Indoor Blower On
Delay Timer Started
Ignitor OFF
Combustion Air
Inducer OFF
Ignitor OFF