Lennox International Inc 110V60C Troubleshooting Heating Sequence of Operation, Thermostat, Page

Troubleshooting: Heating Sequence of Operation

IGNITION AND CALL FOR LOW FIRE WITH TWO−STAGE

1 THERMOSTAT

Safety

Check

Verify There
Is No Main Burner
Flame
	Indoor blower OFF	After
	Heat OFF Delay		YES
	(Low Heat Speed)

Limit

Switch NO

Closed?

YES

Rollout

Circuit NO

Closed?

L

I

GYES

H

T

De−Energize Gas Valve

De−Energize Gas Valve

Combustion Air

Inducer On

(100% rate

speed)

Combustion Air Inducer On (100% rate speed)

Indoor Blower

ON (70%)

Error Code	Indoor Blower		Limit
			Closes Within 3		NO
Flashes	ON (100%)
			Minutes?
				Indoor Blower OFF
				After Heat OFF Delay
				(High Heat Speed)
		Rollout	YES		Soft Lockout:
Error Code					Error Code
		Circuit				1
Flashes					Flashes
		Closes?
	NO		Combustion Air
			Inducer OFF
			After Post−Purge

OLow

F	Pressure	NO
F	Switch
	Open?

	High
Error Code Flashes	Pressure
After 5 Seconds	Switch
	Open?

	Error Code Flashes	Indoor Blower OFF After
NO
	After 5 Seconds	Heat OFF Delay

C A L L

F O R

1 S T

S T A G

Low Pressure

High Pressure

Switch Opens

YES

Switch Opens

YES

Combustion Air

Inducer ON at 70%

Rate Speed

YES

Low

4

Pressure Switch

NO

Pressure Switch

Calibration

NO

Calibrations

YES

Closed Within 150

Calibration

Successful?

Attempted?

Seconds?

NO

YES

Wait

5 minutes

Pre−Purge

15 Seconds

Ignitor ON

Interpurge

20 Seconds

(15 Seconds)

Gas Valve

Energized

NO

Ignition Trial Begins

Indoor Blower Delay

(Ignitor ON)

Timer Started

Gas Valve

Flame

De−energized

5th

Post−Purge

Sensed Within

NO

Unsuccessful

YES

(20Seconds)

4 seconds?

Ignitor OFF

Trial?

Hard Lockout:
Error Code
Flashesfl	2

Call
For	NO
Heat?	NO
YES
Soft Lockout:	Call For
Error Code	Heat
Flashes	Ends?
	YES
	Indoor
	Blower
	ON?

YES NO

Indoor blower OFF

After Heat OFF Delay

1

Combustion	Soft Lockout:
Air Inducer	Error Code	1
OFF	Flashes

E

H E A T

YES

Ignitor OFF

Wait For Ignition

Stabilization Delay

1SOFT LOCKOUT IS RESE T AUTOMATICALLY AFTER ONE HOUR WITH A CALL FOR HEAT ACTIVE,

	Set Target Firing Rate		OR BY CYCLING THE CALL FOR HEAT, OR BY CYCLING POWER TO THE CONTROL.
	Based on Thermostat		2 HARD LOCKOU T IS RESE T BY CYCLING POWER TO THE CONTROL.
	Signals Present
	OR
2		3A

Call For 2nd Stage Heat Call For Heat Satisfied

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