69-2088—01 - S9240F1004 Modulating Hot Surface Ignition ... · S9240F1004 MODULATING HOT SURFACE IGNITION INTEGRATED FURNACE CONTROL 3 69-2088—01 INSTALLATION When Installing

INSTALLATION INSTRUCTIONS

69-2088-01

®Automatic Ignition SystemsANSI Z21.20

S9240F1004 Modulating Hot SurfaceIgnition Integrated Furnace Control

APPLICATIONThe S9240F1004 Integrated Furnace Control (IFC) is designed specifically to work with a Lennox G71MPP variable firing rate, high efficiency furnace. It provides gas ignition, safety shutoff, and variable speed fan control with multi-firing rate gas heating and up to 2-stage electric cooling applications.

FEATURESThe S9240F1004 provides the following features:• Monitors a single stage or 2-stage conventional low

voltage thermostat for requests for heat, cool, or fan.• Monitors an input provided for connection to a

thermostat with a dehumidification output or Harmony III Zone Control.

• Provides three stage furnace input rate control when operating with a conventional single stage thermostat.

• Provides 2-stage or modulating furnace input rate control based on field selected option when operating with a conventional 2-stage thermostat.

• Manages ignition of a main burner flame up to 400,000 BTU per hour using a 95 V hot surface igniter.

• Monitors the appliance pressure, limit, and rollout switches and generate control actions as programmed.

• Controls the 24 Vac Honeywell amplified gas/air gas valve.

• Controls a 3-phase 120 Vac inducer motor (Fasco Model 92B1 or other with identical voltage/frequency curve) and blower assembly based on heat demand and other parameters.

• Controls the Regal Beloit 3.0 ECM circulator motor and blower based on defined appliance CFM profiles and/or a discharge air sensor signal.

• Controls single stage or 2-stage cooling equipment. The outdoor unit is controlled directly by the 24 Vac conventional thermostat inputs. The IFC manages the circulator speed based on cool demand and other parameters.

• Controls a 120 Vac humidifier output and a 120 Vac EAC output.

• Operates with 120 Vac single phase, 60 Hz power supply.

• Uses a 7-segment LED display to communicate error code and status information. A single on board button is provided to generate the desired information display.

• Provides field selectable DIP switches to select field specific control operating parameters such as type of thermostat, delay timings, and fan operating parameters.

• Provides on-board jumpers that can be clipped to permanently enable 2-stage cooling, heat pump compatibility, dehumidification sequences, and define appliance characteristics for field replacement purposes.

• Provides Field Test Mode and Diagnostic Recall Mode to assist the installation/service technician.

• Stores the 10 most recent error codes, which are accessible by the service technician in Diagnostic Recall Mode.

S9240F1004 MODULATING HOT SURFACE IGNITION INTEGRATED FURNACE CONTROL

69-2088—01 2

SPECIFICATIONS

Electrical RatingsLine Voltage Supply: 97-120 Vac, 58-62 Hz; single phase (132 Vac and 62 Hz maximum)

Input Voltage: 18-24 Vac (30 Vac maximum)

Input Current: 500 mA (control only)

Current Draw: 0.5A Input Current plus valve load and optional 24 VAC humidifier load at 24Vac

Igniter Current: 1.0A resistive at 95 Vac output

Induced Draft Blower: 33-110 Vac; 45-180 Hz; 1.1 A at 110 Vac 3-phase (full load)

Gas Valve: 1.5 A at 30 Vac; Inrush current 3.0 A at 30 Vac; Inrush duration 16 ms

Line Voltage Humidifier: 1A resistive load maximum at 120 Vac

Electronic Air Cleaner: 1A resistive load maximum at 120 Vac

Gas Control: Honeywell VK8105R variable firing rate, 24 Vac valve

Cooling Contactor: Any 24 Vac contactor rated at 1.0A or less

TimingsPrepurge: 15 seconds

HSI Warm-up: 20 seconds

Trial for Ignition: 4 seconds

Ignition Stabilization Period: 10 seconds

Flame Failure Response Time: 2 seconds maximum

Gas Valve Sequence Period: 20 seconds

Postpurge: 20 seconds (15 seconds at current fire rate and 5 seconds at 40% fire rate)

Interpurge: 15 seconds

Auto Restart Delay: 60 minutes (after Soft Lockout)

Ignition Trials: Five total; four retries if flame is not sensed on the first trial

Ignition Recycles: 4 total; 3 recycles if flame lost on first trial

Second Stage Recognition Delay: 30 seconds (only on First Call for High Fire on a Call for Heat)

Second Stage ON Delay: 7 or 12 minutes - when used with a single stage thermostat (see Table 5 on page 8); default is 7 minutes

Third Stage ON Delay: 10 minutes - when used with a single stage thermostat

Fan Delays:Heat Fan ON Delay: 45 secondsHeat Fan OFF Delay: 60, 90, 120, or 180 seconds; default

90 seconds; see Table 5 on page 8Cool Fan ON Delay: 2 seconds plus selected Cooling Pro-

file; see Table 6 on page 9Cool Fan OFF Delay: selected Cooling Profile; see Table 6

on page 9

Circulator Speeds:Heat: various settings available; see Table 7 on page 10Cool: low, medium-low, medium-high, and high speeds

available; see Table 6 on page 9Fan - Thermostat “G”: low, medium-low, medium-high, and

high speeds available; see Table 5 on page 8

LEDThe 7-segment LED communicates:• System status• Error codes• Enables, via a pushbutton, alternate modes (Idle,

Diagnostic, and Field Test) of operation

OperatingOperating Temperature: -40°F to +175°F (-40°C to +79°C)

Storage Temperature: -40°F to +185°F (-40°C to +85°C)

Relative Humidity: 0% to 95% non condensing

ApprovalsCSAANSI Z21.20


3 69-2088—01

INSTALLATIONWhen Installing This Product…

1. Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condi-tion.

2. Check the ratings given in these instructions to make sure the integrated furnace control is suitable for your application.

3. Installer must be a trained, experienced service techni-cian.

4. After installation is complete, check out operation as provided in these instructions.

WARNINGFire or Explosion Hazard.Can cause severe injury, death or property damage.1. The integrated furnace control can malfunction if it

gets wet, leading to accumulation of explosive gas.— Never install where water can flood, drip or

condense on the IFC.— Never try to use an integrated furnace control

that has been wet—replace it.2. Liquefied petroleum (LP) gas is heavier than air

and will not naturally vent upward.— Do not operate electric switches, lights, or

appliances until you are sure the appliance area is free of gas.

WARNINGElectrical Shock Hazard.Can cause severe injury, death or property damage.Disconnect power supply before beginning wiring or making wiring connections to prevent electrical shock or equipment damage.

CAUTIONEquipment Damage Hazard.Water can cause equipment damage or malfunction.If the integrated furnace control must be mounted near water or moisture, provide suitable waterproof enclosure.

LocationThe integrated furnace control is mounted on a panel within the circulator compartment of the furnace. The location must provide:— Access to the field wiring terminals.— Operating ambient temperatures between -40°F and 175°F

(-40°C and 79°C).— Relative humidity below 95% non condensing.— Protection from water, steam or corrosive chemicals that

are used to clean the appliance.— Protection from dripping water, such as from an overfilled

humidifier or from condensation.— Protection from dust or grease accumulation.

MountingThe integrated furnace control is designed to snap into the appliance mounting panel.

1. While holding the controller board with the thermostat terminals (E7) at the bottom, insert the two left-side hooks on the board into the holes in the mounting panel. See Fig. 1 on page 5.

2. Press the board into the mounting panel’s right-side holes until it snaps into place.

WiringCheck the wiring diagrams furnished by the appliance manufacturer, if available, for circuits differing from the general hookup shown. Carefully follow any special instructions affecting the general procedures outlined below.

All wiring must comply with local codes and ordinances.

See Table 1, Table 2, Table 3, and Fig. 1 beginning on page 4 for typical connections, but refer to furnace manufacturer instructions, if available.

See Fig. 2 on page 6 for a typical wiring diagram.


69-2088—01 4

Table 1. Wiring Connections - Class 2 - Low Voltage.

Terminal Type Connection/LabelBoard label(see Fig. 1) Connects S9240F to:

12-position screw terminal block(#5 screw)

W1

E7

Thermostat 1st stage heat input

W2 Thermostat 2nd stage heat input

G Thermostat continuous fan input

Y2 Thermostat 2nd stage cool input

Y1 Thermostat 1st stage cool input

C 24 Volt ground (connected to transformer and chassis ground)

R 24 Volt hot

DH Not used

H - (optional) If used: 24V humidifier output

L Not used

O - (optional) If used: Thermostat signal to heat pump reversing valve input

DS - (optional) If used: Thermostat Dehumidification or Harmony Zoning input

4-position screw terminal block (#5 screw)

Outdoor SensorE4

Not used

Discharge Air Sensor - (optional)

If used: Discharge air sensor

Straight Spade Quick Connect Flame Sense E42 Flame signal input

12-pin connector (male terminals) Main Harness J2 Main valve, pressure switches, rollout, limit, chassis ground, and 24 Vac

6-pin connector (male terminals) Circulator Motor P79 Motor serial control interface and furnace size select input

Table 2. Wiring Connections - Class 1 - Line Voltage.

Terminal Type Connection/LabelBoard label(see Fig. 1) Connects S9240F to:

2 pin connector (male terminals) Igniter P77 – HSI Igniter interface

3-pin connector (male terminals) CAI Connector J3 – CAI 3-phase AC power

Straight Spade Quick-connect Humidifier HUM Humidifier 120 Vac output

EAC EAC Electronic air cleaner 120 Vac output

Neutrals E36, E37,E38, E39,and E40

Any neutral connector can be used for:• 120 Vac Input neutral• Transformer neutral• Electronic air cleaner neutral• Circulator neutral• Humidifier neutral


5 69-2088—01

.

Fig. 1. Typical wiring connections and component locations for S9240F1004 Integrated Furnace Control(minor components removed for clarity).

Table 3. Jumpers.

JumperBoard label(see Fig. 1) Action:

W915 - 2-Stage Compressor W915 UNCUT: Single stage compressor (factory default)CUT: 2-stage compressor

W951 - Heat Pump W951 UNCUT: Compressor heating disabled (factory default)CUT: Compressor heating enabled

W914 - Dehumidifier or Harmony III W914 UNCUT: Harmony III and dehumidifying operation disabled(factory default)

CUT: Harmony III and dehumidifying operation enabled

M28148

EAC HUM

HS

I3 1

17

410

69

312

1517

1614

1819

L1

1

119

810

1312

4

36

1

P80

12

34

56

7

2

NEUTRALS

RC

I –I +

FLAM

ES

EN

SE

OUTDOORSENSOR

DISCHARGEAIR SENSOR

I+

W914

DE

HU

MO

RH

AR

MO

NY

W951

HE

ATP

UM

P

W915

2 STA

GE

CO

MP

R

CU

T FOR

OP

TION

SE

LEC

TION

W1

W2

GY

2Y

1D

HH

OD

SC

OU

TDO

OR

EQ

UIP

ME

NT

IND

OO

RE

QU

IPM

EN

T

R

R

RC

I –I +

LR

I –

TEMPERATURE SENSORS – E4

LED

E7

L1P79CIRCULATOR

MOTORHARNESS

J2MAIN

HARNESS

NEUTRALS E36, E37, E38, E39, AND E40

HUMEACW914DEHUM

ORHARMONY

W951HEATPUMP

W9152-STAGECOMPR

P77HSI

ON

ON

ON

FACTORY USE ONLY.1

1

W1

W2

G

Y2

Y1

C

R

DH

H

L

50029412-001 Rev. A

SIDE HOOK (X2)FOR

PANEL MOUNTING

S3 S2 S1 PUSH BUTTON E42 – FLAME SENSE J3 – CAI


69-2088—01 6

Fig. 2. Typical wiring diagram for S9240F1004 Integrated Furnace Control.

21

31 2 435 11 6 121 8 472 10 9

21 3

5 6

M28147

120 V / 60 HZAC MAINS

3 PHASE COMBUSTIONAIR INDUCER

95V HSI

FLAME RODDISCHARGE AIR SENSOR(OPTIONAL)

FLAME SENSE

HUM

EAC

LINE VOLTAGEHUMIDIFIER(OPTIONAL)

ELECTRONICAIR CLEANER(OPTIONAL)

REGALBELOIT

ECM 3.0INDOOR

AIR BLOWER

24 VAC

MAINVALVE

LOWPRESSURESWITCH

HIGHLIMIT

SWITCH

ROLLOUTSWITCH

HIGHPRESSURESWITCH

W951

W914

W915

24VHUMIDIFIER(OPTIONAL)

L1

L2

1

2P77

P79

J3

J2

E7

E4

M

W1

G

Y2

Y1

C

R

DH

H

L

O

DS

W2

FURNACE SIZEIDENTIFIER

L2 L1

M


7 69-2088—01

SETTINGS AND ADJUSTMENTS

JumpersThree jumpers are located on the S9240 board. The jumpers are all ON (uncut) from the factory. To change any jumper, first disconnect the power, then cut the desired jumper.

Fig. 3. Jumper locations.

DIP SwitchesThere are three DIP switch blocks on the S9240F (see Fig. 4):• S1 – see “DIP Switch S1 Settings”• S2 – see “DIP Switch S2 Settings – Cooling Airflow” on

page 9.• S3 – see “DIP Switch S3 Settings – Heating Airflow” on

page 10.

Fig. 4. DIP Switch locations (S1, S2, and S3).

DIP Switch S1 SettingsFive parameters may be set with this 7-position DIP switch. Refer to Fig. 4 for location of DIP switch S1.

The default factory settings (all OFF) are shown in Fig. 5 and indicated in Bold in Table 5 on page 8.

To change any setting, first disconnect the power, then set SW1 through SW7 according to Table 5 on page 8.

.

Fig. 5. DIP Switch S1 - shown with factory default settings; all OFF.

SW1: STAGE SELECTIONThe stage selection is factory-set (OFF) to a 2-stage thermostat with the 2nd and 3rd stage On Delays disabled.

The ON position configures the IFC for a single stage thermostat with the 2nd and 3rd stage On Delays enabled.

NOTE: Selection of the single stage position (ON) allows three stage operation with a single stage thermostat.

SW2: SEQUENCEThe sequence is factory-set (OFF) to respond to a thermostat as dictated by the SW1 selection.

The ON position configures the IFC for the Lennox modulating firing state sequence with 2-stage thermostat.

NOTE: SW2 position is ignored if SW1 is ON.

SW3: 2ND STAGE ON DELAYThe On Delay timing applies to systems configured only with single stage thermostats. It is the length of time operating in normal low fire mode before switching to high fire mode. The timing is factory-set (OFF) to 7 minutes.

The ON position configures the 2nd stage On Delay for 12 minutes.

NOTE: SW3 position is ignored if SW1 is OFF.

SW4-5: HEAT FAN OFF DELAYThe Heat Fan Off Delay is the period between the loss of supervised main burner flame after the call for heat has ended and the deactivation of the blower motor at the low heat speed. The timing is factory-set (all OFF) to 90 seconds. See Table 5 on page 8 for other timing settings.

SW6-7: FAN SPEED – THERMOSTAT “G”The fan speed is factory-set (all OFF) to Medium-low. See Table 5 on page 8 for other speed settings.

Table 4. Jumper Conditions - Defaults in Bold.

Description

Jumper

W915 W951 W914

Single stage compressor Uncut

2-stage compressor Cut

Disable compressor heating Uncut

Enable compressor heating Cut

Disable Harmony III and dehumidifying operation

Uncut

Enable Harmony III and dehumidifying operation

Cut

M28149

W915 - 2 STAGE COMPRW914 - DEHUM/HARMONYW951 - HEAT PUMP

M28150

S2S3 S1

DIP SWITCH S1

M28151

HEAT FAN OFF DELAY

2ND STAGE ON DELAY

SINGLE OR 2-STAGE THERMOSTATSELECTION

ON 1

24

35

76

FAN SPEED - THERMOSTAT “G”

CONVENTIONAL 2-STAGE OR LENNOX MODULATING SEQUENCE


69-2088—01 8

Table 5. DIP Switch S1 Settings - Defaults in Bold.

Description

Individual Switches

SW1 SW2a SW3b SW4 SW5 SW6 SW7

2-Stage Thermostat: 2nd and 3rd stage On Delay disabled OFF

Single Stage Thermostat: 2nd and 3rd stage On Delay enabled ON

Conventional 2-stage sequence with 2-stage thermostat OFF

Lennox modulating sequence with 2-stage thermostat ON

2nd Stage On Delay - 7 minutes OFF

2nd Stage On Delay - 12 minutes ON

Heat Fan Off Delay - 60 seconds OFF ON

Heat Fan Off Delay - 90 seconds OFF OFF

Heat Fan Off Delay - 120 seconds ON OFF

Heat Fan Off Delay - 180 seconds ON ON

Low fan speed (fan only operation) OFF ON

Medium-low fan speed (fan only operation) OFF OFF

Medium-high fan speed (fan only operation) ON OFF

High fan speed (fan only operation) ON ON

a Switch 2 is ignored if switch 1 is in the ON position.b Switch 3 is ignored if switch 1 is in the OFF position.


9 69-2088—01

DIP Switch S2 Settings – Cooling AirflowDIP Switch S2 is used to adjust the cooling speed and profile. Refer to Fig. 4 on page 7 for location of DIP switch S2.

The default factory settings (all OFF) are shown in Fig. 6 and indicated in Bold in Table 6.

To change any setting, first disconnect the power, then set SW8 through SW13 according to Table 6.

.


SW8-9: COOLING FAN SPEEDThe fan speed during cooling is factory-set to High.

SW10-11: COOLING FAN SPEED ADJUSTMENT (CFM)The fan CFM during cooling is factory-set to normal (Base Tap).

SW12-13: COOLING PROFILEThe fan profile during cooling is factory-set to 30 seconds at 50%, 7.5 minutes at 82%, run at 100%, and with a 30 second Off delay at 50%. Fig. 7 illustrates the factory-set cooling profile. The fan speed ramps up and down during speed changes.

.

Fig. 7. Fan cooling speed ramp up and ramp down profile (factory default shown).

DIP SWITCH S2

M28152

COOLING PROFILE

COOL SPEED

89

1110

1213

COOL SPEED ADJUSTMENT

ON

M28161

30

TIME (SECONDS)

FAN

SPEED

50%

82%

100%

30

1

1 FAN SPEED AS A PERCENT OF MAXIMUM.

450

Table 6. DIP Switch S2 Settings – Cooling Airflow.

Description

Individual Switches

SW8 SW9 SW10 SW11 SW12 SW13

High Cool Speed (circulator) OFF OFF

Medium-low Cool Speed (circulator) OFF ON

Medium-high Cool Speed (circulator) ON OFF

Low Cool Speed (circulator) ON ON

Normal CFM - Base tap OFF OFF

Decrease Cool speed CFM by 10% OFF ON

Increase Cool speed CFM 10% ON OFF

ECM Test Mode (motor slew rates disabled) ON ON

Cooling Profile - On: 30 seconds at 50%, 7.5 minutes at 82%, then run at 100%Off: 30 second Off Delay at 50%

OFF OFF

Cooling Profile -On: No On Delay (run at 100%)Off: 60 second Off Delay at 100%

OFF ON

Cooling Profile - On: 7.5 minutes at 82%, then run at 100%Off: no Off Delay

ON OFF

Cooling Profile - no On or Off Delays ON ON


69-2088—01 10

DIP Switch S3 Settings – Heating AirflowDIP Switch S3 is used to adjust the heating airflow (CFM). Refer to Fig. 4 on page 7 for location of DIP switch S3.

The LOW heat CFM setting adjusts the heating CFM that corresponds to the lowest firing rate of the appliance. The HIGH heat CFM setting adjusts the heating CFM that corresponds to the highest firing rate of the appliance. The CFMs between these two points are interpolated linearly.

The default factory settings (all OFF) are shown in Fig. 8 and indicated in Bold in Table 7.

To change any setting, first disconnect the power, then set SW14 through SW19 according to Table 7.

.


.

DIP SWITCH S3

M28153

1415

1716

1819

LOW HEAT CFM CHANGE (7% OR 15%)

LOW HEAT CFM (NORMAL/MODIFIED)

LOW HEAT CFM (INCREASE/DECREASE)

HIGH HEAT CFM CHANGE (7% OR 15%)

HIGH HEAT CFM (NORMAL/MODIFIED)

HIGH HEAT CFM (INCREASE/DECREASE)

ON

Table 7. DIP Switch S3 Settings – Heating Airflow.

Description

Individual Switches

SW14 SW15a

a Switch 15 is ignored if switch 14 is in the OFF position.

SW16b

b Switch 16 is ignored if switch 14 is in the OFF position.

SW17 SW18c

c Switch 18 is ignored if switch 17 is in the OFF position.

SW19d

d Switch 19 is ignored if switch 17 is in the OFF position.

Normal Low Heat CFM OFF

Modified Low Heat CFM ON

Increase Low Heat CFM OFF

Decrease Low Heat CFM ON

Change Low Heat CFM by 7% OFF

Change Low Heat CFM by 15% ON

Normal High Heat CFM OFF

Modified High Heat CFM ON

Increase High Heat CFM OFF

Decrease High Heat CFM ON

Change High Heat CFM by 7% OFF

Change High Heat CFM by 15% ON


11 69-2088—01

CHECKOUTCheck out the integrated furnace control system:— At initial installation of the IFC.— As part of regular maintenance procedures.— As the first step in troubleshooting.— Any time work is done on the system.

Use the following procedures only for the integrated furnace control; see individual component instructions for additional checkout procedures.

Check Normal Operation1. Turn on power to the appliance.

NOTE: Powering up or cycling power will generate the Pressure Switch Calibration sequence prior to responding to the call for heat.

2. Reset the IFC by turning the thermostat to its lowest setting and waiting five seconds.

3. Set the thermostat to call for 1st stage heat. Make sure the integrated furnace control sequences the system as indicated in Fig. 9 on page 19 (Fig. 12 on page 22 for single stage thermostat).

4. Set the thermostat below the room temperature to end the call for heat. The burner should go out; the induced draft fan should provide postpurge time (20 seconds); and after the delay time, the circulator should stop.

There are several modes of operation. They are discussed in this section in the following order:

1. “Pressure Switch Calibration”2. “Light Off”3. Heat Mode:

a. “Normal Heat Mode - Conventional 2-Stage Ther-mostat (standard 2-stage operation selected)” on page 12, or

b. “Lennox Modulating Mode - Conventional 2-Stage Thermostat (special Lennox sequence selected)” on page 12, or

c. “Normal Heat Mode - Conventional Single Stage Thermostat” on page 13

4. “Cooling Mode” on page 135. “Fan Mode” on page 13

NOTE: Compressor heat, Ignition, Retry, Rollout circuit, Limit switch, Pressure switches, HSI, Humidity control, and Electronic air cleaner operation are discussed beginning on page 13.

Pressure Switch CalibrationA system calibration sequence is required prior to normal use and after AC power is cycled off then on. This process establishes furnace operating parameters in the specific installation and provides data to support robust system operation. The calibration sequence may be repeated at other times as required to help assure optimum performance.

Calibration is required during the initial start up of the furnace installation in the field. All fuel, electrical, venting, condensate drain piping (trap primed), combustion air supplies, as well as conditioned air ducts and returns should be connected prior to calibration.

NOTE: The calibration process takes 60 to 120 seconds to complete successfully. The LED flashes “C A L” during a the calibration cycle.

Successful Calibration Calibration data is stored in volatile memory and is used to determine furnace operation and control parameters in heating mode. The IFC will not perform additional calibrations unless required by changes in the appliance’s operating conditions, if requested by the installer/service person, or by cycling the power to the furnace.

Unsuccessful CalibrationIf the inducer speed limits are reached, and calibration is unsuccessful, the IFC proceeds to a 5 minute delay and flashes the appropriate LED error code. The IFC repeats the calibration sequence four times with a 5 minute delay in between each try, and if still unsuccessful, the IFC moves to Soft Lockout.

Calibration InitiationCalibration initiates by:• The IFC, on the initial call for heat after power-up.• The installer/service person as part of the Field Test Mode.

See “Field Test Mode” on page 26.• The IFC, whenever a venting condition change is detected

including:— Low pressure switch fails to close during the wait for

low pressure switch to close time. Calibration takes place immediately.

— Low pressure switch opens for longer than two seconds during the heating cycle. Heating cycle includes prepurge, HSI warm up, trial for ignition, flame stabilization, and run states. Calibration takes place immediately.

— High Pressure Switch fails to close or open during the heating cycle at 100% firing rate operation. Calibration takes place on the next call for heat.

— Ramp down low fire switch check fails. Calibration takes place on the next call for heat.

The calibration process does not generate any error codes other than the inducer or pressure switch calibration failures. However, If either pressure switch closes before the calibration starts and while the inducer RPM is zero (0), the pressure switch error is generated.

At the end of a successful calibration, if a call for heat is still present, the IFC skips the Prepurge and goes straight into HSI warm-up. This speeds up the heating process and reduces the excess purge.

Light OffRefer to Fig. 9 on page 19 (Fig. 12 on page 22 for single stage thermostat), for the operating sequence during light off. Light off occurs in the following manner for each call for heat and any other situation requiring light off.

The following describes the operation of the IFC during light off:

— The IFC conducts a safe start check that consists of an internal hardware/software self-check and verification there is no main burner flame present.


69-2088—01 12

— The IFC verifies the limit and rollout switch circuits are closed.

— The IFC verifies the low and high pressure switch circuits are open.

— The IFC energizes the inducer and adjusts to the ignition firing rate speed.

— When the low pressure switch closes, Prepurge begins.

— After the completion of Prepurge, the HSI energizes for the Igniter Warm-up Period.

— When the Igniter Warm-up Period expires, the gas valve energizes, the Inducer remains at the ignition firing rate, gas flow begins, and the Trial for Ignition (TFI) begins. • During TFI, the HSI remains energized.

• After TFI, the HSI de-energizes, the gas valve remains energized, and the Inducer remains at the ignition firing rate for the flame recognition period.

— The heat fan on delay is started upon entering Trial for Ignition.

— When flame is sensed during Trial for Ignition, the IFC de-energizes the HSI.

— When the ignition stabilization delay expires, the IFC moves to the ignition firing rate.

— After successful lightoff, the IFC moves to the target firing rate (see note below) based on the current thermostat inputs and the selected operating sequence.

NOTES: Unless the special Lennox modulating sequence is selected (SW1 is OFF and SW2 is ON), there are three target firing rates:

1. Low Fire Rate, which is about 40% of appliance full rate.

2. Mid Fire Rate, which is about 70% of appliance full rate.

3. High Fire Rate, which is about 100% of appliance full fire rate.

Normal Heat Mode - Conventional 2-Stage Thermostat (standard 2-stage operation selected)Refer to Fig. 9-14 beginning on page 19 for the operating sequence diagrams.

Call for Stage 1 HeatA call for 1st stage heat is signaled by the thermostat closing the contacts between R and W1.

Upon a call for 1st stage heat:— After a successful Light Off and expiration of the

ignition stabilization period, the Inducer adjusts to the mid firing rate speed.

— After expiration of the heat fan on delay, the IFC adjusts the circulator to the appropriate speed (CFM).

— If a discharge air sensor is present, the circulator adjusts to maintain the target discharge air temperature.

— The IFC remains in this state until the thermostat generates a 2nd stage call for heat or the 1st stage call for heat is removed.

Call for Stage 2 HeatA call for 2nd stage heat is signaled by the thermostat simultaneously closing the contacts R, W1, and W2.

On the first call for 2nd stage heat, the request is ignored until the 2nd stage recognition delay expires.

When a 2nd stage recognition delay expires (and on subsequent calls for 2nd stage heat in the same heating cycle), the following occurs:

— The Inducer adjusts to the high firing rate speed.— The IFC adjusts the circulator speed to the appropriate

speed (CFM).— If a discharge air sensor is present, the circulator

adjusts to maintain the target discharge air temperature.

— The IFC remains in this state until the 2nd stage call for heat or the 1st stage call for heat is removed.

2nd Stage Heat Satisfied, Call for 1st Stage Heat RemainsWhen the 2nd stage heat request is removed and there is still a demand for heat on the 1st stage, the following occurs:

— The Inducer adjusts to the mid firing rate speed.— The IFC adjusts the circulator speed to the appropriate

speed (CFM).— If a discharge air sensor is present, the circulator


— The IFC remains in this state until the thermostat generates a 2nd stage call for heat or the 1st stage call for heat is removed.

Call for 1st Stage Heat SatisfiedWhen the 1st stage is satisfied:

— The gas valve de-energizes.— When the loss of flame is detected, the Postpurge and

circulator fan off delay timings begin.— When the Postpurge time completes, the inducer

de-energizes.— When the circulator fan off delay expires, the circulator

de-energizes.

1st and 2nd Stages Satisfied SimultaneouslyWhen both 1st and 2nd stages are satisfied simultaneously:

— The gas valve de-energizes.— When the loss of flame is detected, the Postpurge and

circulator fan off delay timings begin.— When the Postpurge time completes, the inducer

de-energizes.— When the circulator fan off delay expires, the circulator

de-energizes.

Lennox Modulating Mode - Conventional 2-Stage Thermostat (special Lennox sequence selected)The Lennox modulating firing rate is proprietary to Lennox. Contact your Lennox representative for specific details.


13 69-2088—01

Normal Heat Mode - Conventional Single Stage ThermostatRefer to Fig. 12 on page 22 for the operating sequence diagram.

Call for HeatA call for heat is signaled by the thermostat closing the contacts between R and W1.

Upon a call for heat, the following occurs:— After a successful Light Off and expiration of the

ignition stabilization period, the Inducer adjusts to the low firing rate speed.

— After expiration of the heat fan on delay, the IFC adjusts the circulator to the appropriate speed (CFM).

— If a discharge air sensor is present, the circulator adjusts to maintain the target discharge air temperature.

— The IFC remains in this state until the selected 2nd stage on delay expires or the call for heat is removed.

When the 2nd stage on delay expires:— The Inducer adjusts to the mid firing rate speed.— The IFC adjusts the circulator to the appropriate speed

(CFM).— If a discharge air sensor is present, the circulator


— The IFC remains in this state until the selected 3rd stage on delay expires or the call for heat is removed.

When the 3rd stage on delay expires:— The Inducer adjusts to the high firing rate speed.— The IFC adjusts the circulator to the appropriate speed

(CFM).— If a discharge air sensor is present, the circulator


— The IFC remains in this state until the call for heat is removed.

Cooling ModeRefer to Fig. 13 on page 23 for the operating sequence diagram.

NOTES:1. If a call for heat and a call for cool are present

simultaneously, the call for heat is serviced. 2. The circulator runs at the highest speed per the

thermostat request.

Single Stage CoolingA call for cooling is signaled by:

— The shorting of R to Y1.— The shorting of R to Y1 and G simultaneously.

Upon a call for cooling:— The compressor and condenser fan energize directly

from the Y1 terminal pass-through signal from the thermostat.

— The IFC does not directly control the compressor and does not provide short cycle protection.

— The circulator energizes two seconds after the cool request.

— The circulator starts according to one of the selectable ramping profiles.

When the cool request is satisfied, the circulator de-energizes per one of the selectable ramping profiles.

Two Stage CoolingThe two stage cooling jumpera on the IFC must be clipped to enable two stage cooling control.

A call for 1st stage cooling is signaled by:— The shorting of R to Y1.— The shorting of R to Y1 and G simultaneously.

A call for 2nd stage cooling is signaled by:— the shorting of R to Y2 while a valid call for first stage

cooling exists.

Upon a call for two stage cooling:— The compressor and condenser fan energize directly

from the Y1 and Y2 terminals pass-through signal from the thermostat.

— The IFC does not directly control the compressor and does not provide short cycle protection.

— The circulator energizes at the low cooling speed two seconds after the 1st stage cool request is detected and switches to high cooling speed immediately after the 2nd stage cool request is detected.

— The circulator starts and operates according to the selected ramping profile.

— When the cool requests are satisfied, the circulator de-energizes per the selected ramping profile.

Fan ModeRefer to Fig. 14 on page 24 for the operating sequence diagram.

— If the IFC is not currently servicing another circulator request, the circulator energizes at the fan speed when R is shorted to G and de-energizes when the request is removed.

— The circulator speed is determined by the dip switch settings. See “DIP Switches” on page 7.

— If the IFC is servicing a fan request and a call for heat or a call for cooling occurs, the circulator remains energized at the continuous fan speed until it is requested to move to the speed required by the heat or cool demand.

Call for Compressor HeatRemoving the “O” jumperb indicates that the IFC is being used in a heat pump system. The thermostat generates the “O” signal. No signal on “O” with 24 Vac on Y1 or Y1+Y2 from the thermostat indicates a call for compressor heat for stage 1 or stage 2 respectively.

These 24 Vac signals directly control a one or two stage heat pump.

— No heat fan on delay is present for compressor heat.— The circulator energizes without delay when

compressor low or high heat is requested.— Compressor heat calls and fossil fuel calls can be

serviced simultaneously. The circulator energizes at the speed requested by the compressor or fossil fuel heat sequence, whichever is higher.

a See jumper W915 in Table 4 on page 7.b See jumper W951 in Table 4 on page 7.


69-2088—01 14

Ignition RetryWhen flame is not sensed during the Trial for Ignition or is lost less than 10 seconds after exiting Trial for Ignition:

— The gas valve is de-energized.— The inducer remains energized at the ignition speed

and holds for the Interpurge Period.— When the Interpurge Period expires, a new trial for

ignition is started again for up to a maximum of four additional trials. After the fifth Trial for Ignition has failed to light the burner the IFC proceeds to Soft Lockout where it remains for the Auto Restart Delay before beginning another set of ignition sequences. The retry count is cleared if flame is sensed for longer than 10 seconds after exiting Trial for Ignition (low fire operation).

Ignition RecycleWhen flame is established during Trial for Ignition, maintained for at least 10 seconds, and then lost:

— The gas valve is de-energized.— The inducer remains energized at the ignition speed

and holds for the Interpurge Period.— When the Interpurge Period expires, a new trial for

ignition is started. A maximum of three recycles are allowed on a single call for heat before the IFC proceeds to Soft Lockout. The recycle count is not cleared until the current demand for heat is satisfied or the IFC has just exited Soft Lockout.

See Table 12 on page 27 for LED error code and lockout information.

Rollout Circuit Operation (during heat cycle)If the rollout circuit opens during a heating cycle:

— The gas valve immediately de-energizes.— The inducer energizes at maximum allowed RPM.

If the switch opens during vent calibration, calibration stops and inducer is run at maximum allowed RPM.

— The circulator energizes at mid heat speed.— The IFC flashes an LED error code indicating the

rollout circuit has opened.— Thermostat requests for heat are ignored.

The IFC remains in this state until the rollout circuit closes.

When the rollout circuit closes:— The inducer de-energizes after the postpurge period. — The circulator de-energizes after the selected heat off

delay.— The LED continues to flash the rollout switch error code.— Thermostat requests for heat are still ignored.

The IFC remains in this state until power is cycled or a thermostat reset at which time the IFC resumes normal operation.


Limit Switch Circuit Operation (during heat cycle)NOTE: If the limit switch circuit opens in any mode other

than heat, it is ignored.

If the limit switch circuit opens during a heating cycle: — The gas valve immediately de-energizes.— The inducer de-energizes after the postpurge period.— The IFC flashes an LED error code indicating the limit

circuit is open.— The circulator immediately energizes at high speed.

The IFC remains in this state until the limit switch circuit closes.

When the limit switch circuit closes:— If the limit switch was open for less than three minutes,

a new ignition sequence starts and the circulator remains energized for the selected fan off delay. If the burner lights before expiration of the selected fan off delay, the fan off timing is stopped and the circulator remains energized.

— If the limit switch was open for longer than three minutes, the circulator remains energized at high heat speed for the selected heat off delay, the error code flashes, and (after the heat fan off delay expires) the IFC proceeds to Soft Lockout where it remains for the Auto Restart Delay.


Low Pressure Switch Operation (during heat cycle)

— If a call for heat exists and the low pressure switch is already closed (before the ignition sequence begins), the IFC waits five seconds. • After five seconds, and if the low pressure switch is

still closed, the IFC flashes an LED error code indicating the low pressure switch is stuck closed.

• The IFC remains in this state until the low pressure switch opens or the call for heat ends.

• As soon as the pressure switch opens the error code clears and the ignition sequence proceeds as normal.

— If the ignition sequence has begun and the low pressure switch fails to close within 150 seconds of energizing the inducer:• The IFC de-energizes the inducer and then

attempts a pressure switch calibration routine.

• The IFC flashes (until calibration completes successfully) an LED error code indicating indicating a failed pressure switch.

• If the calibration is unsuccessful, the IFC flashes an LED error code indicating an unsuccessful calibration and begins a five minute delay.

• The IFC attempts the calibration routine three more times (four total) before entering a one hour Soft Lockout.


15 69-2088—01

• This process repeats until the calibration routine is successful or the call for heat ends.

— If the low pressure switch opens for less than two seconds during Prepurge or Igniter warm-up:• The IFC completes the ignition sequence.

• If the appliance fails to light after the maximum number of retries has been exceeded, the IFC proceeds to Soft Lockout and attempts the pressure switch calibration routine.

— If the low pressure switch opens for longer than two seconds during Trial for Ignition or normal operation (Run Mode):• The IFC proceeds to Postpurge followed by the

vent calibration sequence, before attempting the ignition sequence again.

• The IFC flashes an LED error code indicating the pressure switch failed open until the vent calibration sequence begins.


High Pressure Switch Operation (during heat cycle)The high pressure switch determines the inducer speed required to achieve the high firing rate of the appliance. The determination is made by the IFC during the calibration process.

The high fire pressure switch should remain closed during high fire operation.

— If it opens during high fire operation, the IFC increases the inducer speed, up to the maximum allowed RPM, in an attempt to re-close the high pressure switch.

— If the high pressure switch re-closes successfully, the IFC completes the Heat mode, and performs the vent calibration on the next call for heat.

— If the high pressure switch remains open, the IFC ends the call for heat and performs the pressure switch calibration routine.

The high pressure switch check takes place during calibration. If the switch is stuck open or closed, calibration will not be completed and the IFC flashes an error code.


Hot Surface Igniter (HSI) ControlThe Hot Surface Igniter is voltage controlled to maintain 95V +/- 5% over a range of 98 to 132V line input. The HSI warm up time is fixed for all ignition trials. Both the continuity of the igniter and the ability of the triggering circuit to energize the igniter are continuously monitored during the Igniter Warm-up and Ignition Activation periods. If a problem is detected, the IFC flashes an LED error code.


Humidity ControlHumidity control is available via line voltage or low voltage operation.

Line Voltage HumidifierThe line voltage humidifier output is energized when either of the following conditions are met:

— Anytime both the inducer and circulator are energized and there is no cool request present.

— A request for compressor heat is active.

Low Voltage HumidifierThe H terminal on the thermostat blocka is available for connection to a 24 volt humidifier. The 24 Vac power is supplied by the system transformer.

The IFC energizes the H terminal with 24 volts when either of the following conditions are met:

— Anytime both the inducer and circulator are energized and there is no cool request present.

— A request for compressor heat is active.

Standard Dehumidification The dehumidification jumperb must be clipped to enable standard dehumidification.

The DS terminal on the thermostat block must connect to the dehumidification output on a conventional thermostat or to the DS output of a Harmony Zoning Control.

The IFC varies circulator speed operation based on the DS signal from the thermostat or Harmony Zoning Control. Refer to the “Harmony III Operation” for operation with Harmony.

Harmony III OperationThe dehumidification jumperb must be clipped for operation with the Harmony III zone control. Once this jumper is clipped, the presence of a Harmony system versus a standard dehumidification control is automatically detected by the IFC.

When the IFC is properly connected to a Harmony III zone control operation is as follows:

— Switches 1 and 2 on DIP switch S1, which configure the IFC for operation with various types of thermostats, are ignored.

— The discharge air sensor is ignored.— Circulator fan speed is determined by the PWM signal

on the DS terminal.— Upon a call for heat with Harmony III present, the IFC

follows the proprietary Lennox modulating firing rate.

Electronic Air CleanerThe line voltage EAC output energizes anytime the circulator is energized, regardless of speed.

a See “Wiring Connections - Class 2 - Low Voltage.” on page 4.

b See jumper W914 in Table 4 on page 7.


69-2088—01 16

Error ConditionsThe following section lists the IFC operating sequence for the stated error conditions.

Main Valve SensingThe IFC monitors the main valve output at all times.

— If the inducer is off and voltage is detected on the valve for longer than the fault debouncing time (e.g. miswire):• All outputs are turned off except for the inducer,

which energizes at low speed.

• The circulator energizes at the mid heat speed.

• If a call for cool occurs, the IFC energizes the circulator at the correct cool speed.

• The IFC flashes an LED error code indicating there is a hardware malfunction.

— If voltage is no longer detected on the valve for more than the fault debouncing time:• The IFC proceeds to Postpurge and de-energizes

the circulator after the selected heat off delay.

• After Postpurge the IFC proceeds to normal operation.

— If the inducer is energized and the main valve relay contacts are sensed closed even though the relay is not energized (welded contacts):• The IFC flashes an LED error code indicating there

is a hardware malfunction.

• The inducer immediately switches off in an attempt to open the pressure switch.

• If, after 5 seconds, flame is sensed or voltage is sensed on the main valve, the IFC energizes the inducer at ignition fire rate speed and the circulator on mid heat speed.

• If flame is not sensed and voltage on the main valve is no longer sensed, the IFC proceeds to a Soft Lockout where it remains for the Auto Restart Delay period.

— If voltage is not detected on the valve for longer than the fault debouncing time during a period when the valve is to be energized (contacts failed to make):• The IFC proceeds as if flame is not sensed.

• If Soft Lockout is entered due to this condition, the IFC flashes an LED error code indicating failed hardware.

Flame Out of SequenceThe IFC does not take action on flame sensed in Idle Mode when there is no call for heat present.

If the IFC is servicing a call for heat and flame is sensed when it is not expected to be present, the ignition and fan sequences are not allowed to progress and the IFC remains in its current state. The exception is Igniter Warm-up where the IFC proceeds to Prepurge.

If the sensed flame goes away before the Flame Debounce Period, the ignition sequence proceeds as normal. If however, the sensed flame lasts longer than the Flame Debounce Period:

— The igniter de-energizes.— The inducer energizes at ignition fire rate speed, and

the circulator energizes at mid heat speed. — The IFC flashes an LED error code indicating the

flame is sensed out of sequence.— Once the sensed flame goes away, the IFC proceeds

to Postpurge followed by Soft Lockout with a flashing LED error code. The Soft Lockout error code is cleared when Idle Mode is entered.

Line Voltage SensingLine voltage sensing is used only for HSI voltage regulation. Line voltage is measured between L1 and Neutral. The level of the line voltage input is monitored at all times.

— If line voltage is measured to be less than 90V RMS (+/- 5%):• The IFC proceeds to Soft Lockout and flashes an

LED error code indicating low line voltage.

• Calls for cooling and fan are serviced while low voltage is sensed.

— If line voltage is measured to be greater than 150V RMS (+/- 5%):• The IFC proceeds to Soft Lockout and flashes an

LED error code indicating high line voltage.

• Calls for cooling and fan are serviced while low voltage is sensed.

Cool and fan operation is not affected by low/high line voltage. In heating mode, if a high or low line voltage condition is detected, the heating cycle ends. If the circulator is running, it turns off after the heat off delay.

The presence of an earth ground or reversed line polarity has no effect on flame sensing. The IFC does require an electrical connection between the transformer common and the burner to ensure proper flame sensing. This electrical connection is to be provided in the appliance wiring harness and is not monitored by the IFC.

Weak Flame Sensing— After a successful Trial for Ignition, while operating at

any firing rate, if the IFC senses a weak flame signal for longer than the fault debouncing time:• the IFC flashes an LED error code indicating there

is a poor flame signal. A strong flame must be sensed for longer than the fault debouncing time or the heat demand must be removed to clear the error code.

Hot Surface Igniter (HSI) Sensing— If the HSI is open-circuited or the associated circuitry

is no longer capable of energizing the HSI:• the IFC flashes an LED error code indicating a

failed ignition circuit and proceeds to Soft Lockout where it remains for the Auto Restart Delay period.

• If the inducer is energized at the time the fault is detected, it remains on for a 15 second purge period before the IFC proceeds to Soft Lockout.


17 69-2088—01

— If the HSI triggering circuitry is sensed as shorted while waiting for the low pressure switch to close or during Prepurge:• the inducer immediately de-energizes

• The IFC flashes an LED error code indicating an internal error.

ResetsThe IFC is reset from Lockout by any one of the following three ways:

— Cycling power – Remove power for longer than 10 seconds.

— Thermostat Reset – Remove the call for heat for longer than three seconds but less than 20 seconds.

— Auto Restart (Soft Lockout only) – The IFC automatically exits Soft Lockout after the Auto Restart Delay expires (assuming the fault that sent the IFC to Soft Lockout has cleared).

Indoor Blower Motor FailureThe IFC monitors communication from the indoor blower motor and takes action for reduced airflow and failed motor conditions as described below.

1. Reduced circulating airflow operation (plugged filter, too small duct, etc.) with RBC 3.0 Indoor Air Blower (IAB) motor:

— In heating mode:• The IFC calls for the CFM required to match the

target heat input rate.

• The IFC monitors continuously status of the motor to insure adequate airflow for the target heating input rate.

• RBC 3.0 motor provides constant airflow for a given range of duct static pressure. When duct static pressure exceeds the capability of the motor (for example, due to a blockage), the motor enters a power limiting mode called “cutback”. This operation is internal to the motor logic and occurs when the RPM required to achieve the target CFM is higher than the motor’s capability.

• The IFC takes the following action when the RBC 3.0 motor reports the cutback mode operation:

(a) As soon as the motor enters cutback mode, the IFC flashes the appropriate LED error code.

(b) The IFC reduces the input rate by the decrease amount shown in Table 8 and adjusts the CFM to match. The appliance continues to run at the new rate for a mini-mum of one minute to allow the system to stabilize.- If the motor exits cutback mode, then the IFC maintains this input rate as the maxi-

mum for the duration of the heat cycle, and flashes the appropriate LED error code.- If the motor does not exit cutback mode, the IFC reduces the input rate by another step and adjusts the CFM to match. This sequence continues until the motor exits cut-back mode.

(c) If the IFC has reduced the input rate down to minimum (40%) and the RBC 3.0 motor is still in cutback mode, the IFC shuts down the furnace, activates the blower off delay, enters soft lockout, and flashes the appropri-ate LED error code.

— Cooling or Continuous Fan Mode:• The IFC calls for the CFM required for cool stage or

continuous fan operation.

• The IFC continuously monitors the status of the motor.

• The RBC 3.0 motor provides constant airflow for a given range of duct static pressure. When duct static pressure exceeds the capability of the motor, the motor enters a power limiting mode called “cutback”. This operation is internal to the motor logic.

• The IFC continues normal cooling or continuous fan operation but flashes an appropriate LED error code if the motor enters cutback mode. The LED error code displays for entire cycle, but is cleared upon completion of the thermostat call for cooling.

2. Failed RBC 3.0 Indoor Air Blower (IAB) motor (dead motor, no power to motor, stuck wheel, no communica-tions with motor, etc.)

— Standby Mode: • The IFC continuously monitors for motor issues,

and flashes appropriate LED error codes. The IFC takes no action on thermostat calls.

• The IFC clears the error code upon resolution of the motor issue and proceeds with normal operation.

— Heating Mode • Upon call for heat – The IFC will not initiate call for

heat if a motor issue exists. The IFC flashes an LED error code, and holds until the error clears.

• During call for heat – The IFC de-energizes the gas valve, immediately turns off the blower, proceeds to normal post purge, flashes an LED error code, and holds until the error clears. (If communication is down the motor may not receive the command.)

Inducer Motor FailureThe IFC constantly monitors the Inducer Motor current consumption.

If the current is out of acceptable range (too high), action is taken as follows:

— Over-current (current too high) – The IFC enters Soft lockout and flashes the appropriate LED error code.

— A new ignition sequence initiates after the auto reset from Soft Lockout.

NOTE: Under-current is not reported as an error.

Table 8. Indoor Blower Motor.

Motor HP Cutback RPMFiring Rate

Decrease Amount

1/2 1300 10%

1 1300 10%


69-2088—01 18

Check Safety Shutoff Operation1. Shut off the gas supply at the manual gas valve ahead

of the appliance.2. Set the thermostat to call for heat. System should oper-

ate as indicated in Fig. 9 on page 19 or Fig. 12 on page 22.

3. Following lockout, open the manual gas valve and make sure no gas is flowing to the burner.

Operating SequencesFigures 9 through 14 beginning on page 19 describe the various operating cycles (Light Off, Heat, Run, Cool, and Fan) of the S9240F1004 Integrated Furnace Control (IFC).


19 69-2088—01

Fig. 9. S9240F sequence on Light Off and Call for 1st Stage Heat cycle (2-stage thermostat).

1. Light Off and Call for 1st Stage Heat (2-Stage Thermostat)

M28154Call For 2nd Stage Heat Call For Heat Satisfied

LimitSwitch

Closed?Circulator OFF AfterHeat Fan OFF Delay(High Heat Speed)

LimitCloses Within 3

Minutes?NO

Soft Lockout:Error Code

Flashes

flashes

YES

Inducer ON(Max Speed)

RolloutCircuit

Closed?

LowPressureSwitchOpen?

LowPressure Switch

Closed Within 150Seconds?

HighPressureSwitchOpen?

YES

NO

NO

NO

NO

YES

NO

Circulator ON(Max Speed)

Inducer ON(Max speed)

Circulator ON(Mid Speed)

De-EnergizeGas Valve


Error CodeFlashes

Error CodeFlashes

RolloutCircuit

Closes?

Inducer OFF After Post-Purge

Circulator OFF AfterHeat Fan OFF Delay

Hard Lockout:Error Code

Flashes

Error Code FlashesAfter 5 Seconds


LIGHT

OFF

SafetyCheck


(Low Heat Speed)

Verify ThereIs No Main Burner

Flame

YES

YES

Low PressureSwitch Opens

High PressureSwitch Opens

YES

Inducer ONat Ignition

Firing Rate Speed

NO Pressure SwitchCalibration

Pre-Purge15 Seconds

YES

H.S.I. ON20 Seconds

Gas ValveEnergized

Ignition Trial Begins(H.S.I. ON)

Heat Fan On DelayTimer Started

FlameSensed Within

4 seconds?

H.S.I. OFF

Gas ValveDe-energized

H.S.I. OFF

Interpurge(15 Seconds)

5thUnsuccessful

Trial?

Wait For IgnitionStabilization Delay

Post-Purge(20Seconds) Inducer OFF


FlashesYES

NO

NO

YES

Call ForHeat

Ends?

NO


YES

CirculatorOn?

YES NO

CALL FOR

1ST

STAGE

HEAT

3A2

1

1

– OR –

CallFor

Heat?NO

4Calibrations Attempted?

CalibrationSuccessful?

Wait5 minutes

NO

NOSoft Lockout:Error Code

FlashesYES

YES

YES

2

1

1

2

Set Target Firing RateBased 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


69-2088—01 20

Fig. 10. S9240F IFC sequence on Call for 2nd Stage Heat cycle (2-stage thermostat).

2. Call for 2nd Stage Heat (2-Stage Thermostat)

M28155

1st Callfor High

Fire?

Wait for Call for Heat Satisfied

2 StageThermostat

2nd StageRecognition Delay

(30 Seconds)

YES

Inducer ON(High Fire Speed)

IncreaseInducer Speed

if Not at Maximum

HighPressure SwitchCloses Within10 Seconds?

NO Error CodeFlashes

NO

YES

Wait 5Minutes

3A

2

Adjust Circulator To Appropriate Speed

SYSTEM WILL ALWAYS LIGHT ON LOW FIRE, EVEN IF 2ND STAGE CALL FOR HEAT IS IN PLACE.

SPECIAL LENNOX MODULATING MODE HAS NOT BEEN SELECTED.

IF THE HIGH PRESSURE SWITCH DOES NOT CLOSE WITHIN 5 ATTEMPTS, THE SYSTEM WILL OPERATE AT LOW FIRE FOR THE REMAINDER OF THE CALL FOR HEAT REQUEST.

1

2

3

1

2

3


21 69-2088—01

Fig. 11. S9240F IFC sequence Call for Heat Satisfied (Run Mode) cycle.

1st Stage Heat

2nd Stage Heat

RUN MODE (2-STAGE THERMOSTAT):1ST OR 2ND STAGE CALL FOR HEAT.

ALL INPUTS MONITORED (LIMIT, PRESSURE,CALL FOR HEAT/COOL, FLAME LEVEL).

3. Call for Heat Satisfied

2nd StageCall for Heat

satisfied?

NO

Inducer speed switchedto Mid speed

Adjust Circulator to appropriate speed

1st StageCall for Heat

satisfied?

Gas valveDe-Energized

Inducer OFFafter

20 second Post Purge

Circulator OFFafter OFF Delay

YES

M28156

NO

Wait for Call -2-Stage Thermostat

Wait for Call -Single Stage Thermostat

1 4

3A 3B RUN MODE (SINGLE STAGE THERMOSTAT):ALL INPUTS MONITORED (LIMIT, PRESSURE,CALL FOR HEAT/COOL, FLAME LEVEL).

– OR –

YES


69-2088—01 22

Fig. 12. S9240F IFC sequence on Light Off and Call for Heat cycle (single stage thermostat).

4. Light Off and Call for Heat (Single Stage Thermostat)

M28157

Call For Heat Satisfied

LimitSwitch

Closed?Circulator OFF AfterHeat Fan OFF Delay(High Heat Speed)

LimitCloses Within 3

Minutes?NO


Flashes

flashes

YES

Inducer ON(Max Speed)

RolloutCircuit

Closed?

LowPressureSwitchOpen?

LowPressure Switch

Closed Within 150Seconds?

HighPressureSwitchOpen?

YES

NO

NO

NO

NO

YES

NO

Circulator ON(Max Speed)

Inducer ON(Max speed)

Circulator ON(Mid Speed)



Error CodeFlashes

Error CodeFlashes

RolloutCircuit

Closes?

Inducer OFF After Post-Purge


Hard Lockout:Error Code

Flashes



LIGHT

OFF

SafetyCheck


(Low Heat Speed)

Verify ThereIs No Main Burner

Flame

YES

YES

Low PressureSwitch Opens

High PressureSwitch Opens

YES

Inducer ONat Ignition

Firing Rate Speed

NO

Pre-Purge15 Seconds

YES

H.S.I. ON20 Seconds

Gas ValveEnergized

Ignition Trial Begins(H.S.I. ON)

Heat Fan On DelayTimer Started

FlameSensed Within

4 seconds?

H.S.I. OFF

Gas ValveDe-energized

H.S.I. OFF

Interpurge(15 Seconds)

5thUnsuccessful

Trial?

Wait For IgnitionStabilization Delay

Post-Purge(20 Seconds) Inducer OFF


FlashesYES

NO

NO

YES

Call ForHeat

Ends?

NO


YES

CirculatorOn?

YES NO

CALL

FOR HEAT

3B

1

4

Move to Mid Firing Rateand High Firing Rate after 2nd and 3rd Stage Delays

(based on DIP Switch selections)

Pressure SwitchCalibration

CallFor

Heat?NO

4Calibrations Attempted?

CalibrationSuccessful?

Wait5 minutes

NO

NOSoft Lockout:Error Code

FlashesYES

YES

YES

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

1

2

1

Set to Low Firing Rate


23 69-2088—01

Fig. 13. S9240F IFC sequence Cooling Mode cycle.

1st Stage CoolingRequest Received

5. Call for Cooling

Energize 1st StageCooling Contactor

(Compressor & Fan)

Energize Circulator(Per Ramping Profile)

Circulator ON After2 Second Delay

2nd StageCooling

Request?

YES

2nd StageCooling Request

Still Active?

De-Energize 1stStage Cooling

Contactor(Compressor & Fan)

YES

1st StageCooling Request

Still Active?

NO

YES

YES

Energize 2nd StageCooling Contactor

(Compressor & Fan)

1st StageCooling Request

Still Active?

De-Energize 2ndStage Cooling

Contactor(Compressor & Fan)

Energize andMaintain Circulator atLow Cooling mode

Energize Circulator(High Cooling mode)

Maintain Circulator(High Cooling mode)

M28158

De-energize CirculatorPer Ramping Profile

NO

NO

YES

NO

5

2ND STAGE COOLING OPERATION REQUIRES A 2-STAGE THERMOSTAT, A 2-STAGECOOLING SYSTEM, AND JUMPER W915 MUST BE CUT. THE CONTROL WILL NOT RESPOND TO A 2ND STAGE COOLING REQUEST UNLESS A 1ST STAGE COOLING REQUEST IS ACTIVE.

CIRCULATOR LOW COOLING MODE AND HIGH COOLING MODE HAVE SPECIFIC ON, OFF, AND SPEED RAMPING PROFILES. THE SPECIFIC PROFILE IS SELECTED USING THEDIP SWITCHES ON THE CONTROL.

1

2

1

2

2

2

1


69-2088—01 24

Fig. 14. S9240F IFC sequence Fan Mode cycle.

Call for Fan

6. Call for Fan

Circulator ON(Speed Determined by

Dip Switch settings)

De-EnergizeCirculator Per

Ramping Profile

NO

Requestfor Heat

Received?

Requestfor CoolingReceived?

NO

YES

Call for FanRemoved?

YES

NO Maintain Circulator atset speed

Maintain Circulator atset speed

YES Maintain Circulator atset speed Go to Call for Cooling

M28159

Go to Call for Heat - 2 Stage Thermostat

Go to Call for Heat - Single Stage Thermostat

6

1

4

5

– OR –

CIRCULATOR LOW COOLING MODE AND HIGH COOLING MODE HAVE SPECIFIC ON, OFF, AND SPEED RAMPING PROFILES. THE SPECIFIC PROFILE IS SELECTED USING THEDIP SWITCHES ON THE CONTROL.

1

1


25 69-2088—01

TROUBLESHOOTING

WARNINGFire, Explosion, or Electrical Shock Hazard.Can cause severe injury, death or property damage.Do not attempt to modify the physical or electrical characteristics of this device in any way. Replace it if troubleshooting indicates a malfunction.

IMPORTANT1. The status codes outlined in Table 12 on page 27 are

a general guide. Follow appliance manufacturer service instructions when available.

2. Take all meter readings within the trial for ignition period. After the ignition period ends and before continuing, reset the system by turning down the thermostat for at least five seconds but for less than 20 seconds.

3. If any component does not function properly, make sure it is correctly installed and wired before replacing it.

4. Static discharge can damage the integrated furnace control. Touch an appliance metal surface to discharge static electricity before touching the furnace control.

5. The integrated furnace control cannot be repaired. If it malfunctions, replace it.

6. Only trained, experienced service technicians should service integrated furnace control systems. Perform the checkout steps listed in the Checkout system before beginning any troubleshooting procedure. After troubleshooting, check out the system again to be sure it is operating normally.

This section describes the LED user interface and the error codes generated by the S9240F control (see “LED Error Codes” on page 27).

LED User InterfaceThe LED user interface consists of a 7-segment LED and a pushbutton as shown in Fig. 15.

Fig. 15. Location of LED and pushbutton.

Single Digit, 7-segment LED displayThe 7-segment LED on the IFC communicates system status and error codes. Refer to Table 10–12 beginning on page 26.

PushbuttonThe pushbutton enables alternate modes of operation such as Field Test Mode and Diagnostic Recall mode. A simple, common use pattern is applied to maintain consistency.

By pressing and holding the pushbutton, The LED cycles through three menu options:• Idle• Diagnostic Recall• Field Test

Every 5 seconds a new menu item displays. If the button is released while that item is shown on the display it is “executed.” Once all items in the menu have been displayed, the menu resumes from the beginning (if the button is still held).

Menu OptionsRefer to the following items and Table 9:• Idle Menu Options

— These options display on the menu when the button is pressed during normal operation.

• Diagnostic Recall Menu Options— These options display when the button is used in

Diagnostic Recall mode.— Displays the 10 most recent error codes.

• Field Test Menu Options— These options display when the button is used in Field

Test mode.

M28160

LED PUSHBUTTON

Table 9. LED Menu Actions.

LED Display SequenceAction When Pushbutton Is

ReleasedIdle Menu Options

No changea

a No Change: The display continues to show whatever is currently being displayed for normal operation (blinking decimal, active error code, heat/cool state, etc.…).

Remain in idle mode

Solid “E” Enter diagnostic recall modeSolid “–” Enter field test mode

Diagnostic Recall Menu OptionsNo change (displaying error history)

Remain in diagnostic recall mode

Solid “≡” (3 horizontal bars) Exit diagnostic recall mode

Solid “C” (for 10 seconds) Clear error historyb

b Clear Error History: Once the button is released, a blinking “C” displays for up to 10 seconds. During this time you must press and release the button one additional time to confirm the action of deleting the error history.

NOTE: Once the error history is deleted, it cannot be recovered.

Field Test Menu OptionsNo change (blinking “–”) Remain in field test modeSolid “–” Exit field test modeSolid “C” Start pressure switch calibration


69-2088—01 26

Field Test ModeIn Field Test Mode you can:• Initiate furnace light-off sequence and move to and hold

low firing rate by applying a W1 signal.• Initiate furnace light-off sequence and move to and hold

high firing rate by applying a W1+W2 signal.• Initiate furnace light-off sequence and move to and hold

mid firing rate by applying a W2 signal.• Change the furnace firing rate between low, mid, and high

by applying and removing W1 and W2 signals.

NOTE: Removal of both W1 and W2 at the same time will cause furnace to shut down.

• Initiate the pressure switch calibration sequence regardless if thermostat signals are present. The furnace performs the low and high pressure switch calibrations and displays “C A L” on the LED. After calibration, the LED returns to the flashing “–” display.

No safety control or other safety related parameters are bypassed during Field Test Mode.

Normal routines (like changing CAI speed if the high pressure switch opens, etc.) are retained as active while in Field Test Mode.

Indoor blower performance and timings will match dip switch selections.

Error code recall and clearing is not available in Field Test Mode.

Field Test Mode is exited by: pressing the push button, cycling main power, or after 45 minutes in Field Test Mode.

Gas Heat Display – System Status

Table 10. Gas Heat LED Display.

DescriptionDisplay Examplea

(LED display in bold)

a The current display mode is immediately interrupted if the operating mode changes

Idle mode Only the decimal symbol blinks. There is no display in idle mode.

Pressure switch proving states, purge states, HSI warm-up, TFI, etc. (All transitional ignition states)

H

Heating stage:Shows what stage of furnace heating is currently operating. Shown only while heating is active and unit is set up to work as staged equipment (not modulating) The display example in this table shows the LED display when the 1st stage heat is active.

H 1 Pause; Display CFMPause; Repeat

Heating input (%):Shows what furnace input percent (40 to 100%) is currently operating. Shown only while heating is active and while unit is set up to work as modulating equipment (not staged). The display example in this table shows the LED display when the furnace input is at 40% heat

H 4 0Pause; Display CFMRepeat

CFM: Shows the current CFM demand of the main blower in actual CFM. The display example in this table shows the LED display when the CFM = 1600.

A 1 6 0 0Pause

Flame Current:Shows the current flame signal in 0.1 μA. The display example in this table shows the flame signal at 10.3 μA.

F 1 0 . 3Pause

Diagnostic recall:Shows the stored diagnostic codes. Diagnostic recall mode times out in 60 seconds. The display example in this table shows the LED display for error 250.

NOTE: A button press interrupts the current display pattern.

NOTE: E 0 0 0 flashes if there are no codes.

E 2 5 0PauseEPauseContinues for up to 10 codes. Pause for 3 seconds and start over.

Fault Memory is clear. 0 0 0 0Return to normal operation

Vent Calibration C A LPause

Field Test Mode - Idle “–” flashesField Test Mode - HeatingThe display example in this table shows furnace input at 40% Heat.

NOTE: The flame current displayed, is the value read when the push button was pressed at the beginning of the LED display sequence.

H 4 0Pause; Display CFMPause; Display Flame CurrentRepeat


27 69-2088—01

Compressor Heating/Cooling Display – System Status

LED Error CodesThere are four types of LED error codes:• Warning Only: IFC continues normal operation.• Wait for Recovery: IFC resumes normal operation after

fault recovers.• Soft Lockout: A state caused by failure internal to the

control or by a system fault such as loss of flame or pressure switch failure. Heating related functionality is

inhibited during Soft Lockout. Assuming the fault that sent the IFC to Soft Lockout has cleared, Soft Lockout exits after the Auto Restart Delay when a call for heat is active. The operator can cycle power to remove the Soft Lockout without waiting for the Auto restart Delay.

• Hard Lockout: A state caused by a failure internal to the control or by a system fault such as a flame rollout. Heating related functionality is inhibited during Hard Lockout. Hard Lockout can be exited only by cycling power to the IFC.

Table 11. Compressor Heating/Cooling LED Display.

DescriptionDisplay Examplea

(LED display in bold)

a The current display mode is immediately interrupted if the operating mode changes

Heating Stage: Shows what stage of furnace heating is currently operating. Shown only while heating is active and unit is set up to work as staged equipment (not modulating).The display example in this table shows the LED display when the 1st stage heat is active.

H 1PauseDisplay CFMRepeat

Dehumidification Mode:Shows that the unit is providing dehumidification instead of straight cooling.

DPauseDisplay CFMRepeat

Cooling Stage:Shows what stage of cooling is currently operating.The display example in this table shows the LED display when the 2nd stage cooling is active.

C 2PauseDisplay CFMRepeat

Defrost Mode:Shown only while in an active defrost(simultaneous Y, W, and O).

D FPauseDisplay CFMRepeat

Table 12. LED Status Codes.

Error/Fault Condition CodeError Handling

(in addition to displaying error code) ResultOutside air sensor out of range(open or no discharge air sensor is OK)

180 None

Warning Only

Low flame in run mode 240 NoneDischarge air sensor (DAS) out of range (open or no discharge air sensor is OK)

310 None

Firing rate reduced to match CFM 311 Reduce firing rate every 60 seconds to match available CFM.Restricted airflow cooling or continuous fan 312 None

Line voltage low 110 Resume normal operation after fault recovers.

Wait for Recovery

Line voltage high 113 Resume normal operation after fault recovers.Zero crossing not detected or frequency out of range

115 Resume normal operation after fault recovers.

Low 24 volts 115 Resume normal operation after fault recovers.Flame circuit check error 125a Resume normal operation 300 seconds after fault recovers.

Hardware failure 125a Resume normal operation 300 seconds after fault recovers.

Micro inter-communication failure 125a Resume normal operation 300 seconds after fault recovers.

Circulator communication failed 201 Resume normal operation after fault recovers.Gas valve miswire 204 Resume normal operation after fault recovers.Low pressure switch failed (stuck) Open 223 If longer than 300 seconds, start pressure switch calibration.


Automation and Control SolutionsHoneywell International Inc. Honeywell Limited-Honeywell Limitée1985 Douglas Drive North 35 Dynamic DriveGolden Valley, MN 55422 Toronto, Ontario M1V 4Z9customer.honeywell.com

® U.S. Registered Trademark© 2007 Honeywell International Inc.69-2088—01 M.S. 11-07

Low pressure switch failed (stuck) Closed 224 Resume normal operation after fault removed.

Wait for Recovery

High pressure switch failed (stuck) Open 225 Increase inducer RPM every few seconds. If upper limit reached, start pressure switch calibration.

High pressure switch failed (stuck) Closed 226 Wait for it to open, then start calibration.Low pressure switch opened in run or Trial for Ignition

227 Increment recycle/retry. Go to Soft Lockout if > maximum

Limit switch circuit open 250 Wait for Limit switch circuit to close. If closed in 3 minutes, resume operation, else enter Soft Lockout after close.

Valve relay contact failure 125a Soft Lockout after fault recovers.

SoftLockout

Inducer/pressure switch calibration failure 228 Retry after 5 minutes. If failed allowed times, go to Soft Lockout. Error counter cleared when exiting lockout.

Flame out of sequence while flame still present

241 Wait for flame loss, then go to Soft Lockout. Error counter cleared when exiting lockout.

Retry > maximum – last one due to no flame 270 Retry. If failed allowed times, go to Soft Lockout. Error counter cleared when exiting lockout.

Retry > maximum – last one due to low pressure switch open

271 Retry. If failed allowed times, go to Soft Lockout. Error counter cleared when exiting lockout.

Recycle > maximum – last one due to low pressure switch open


Recycle > maximum – last one due to flame lost in run mode


Limit switch open > 3 minutes 274 Soft Lockout. Error counter cleared when exiting lockout.Flame out of sequence and flame is gone 275 Soft Lockout. Error counter cleared when exiting lockout.Failed ignitor or trigger circuit 290 Soft Lockout. Error counter cleared when exiting lockout.Available CFM below minimum firing rate 291 Soft Lockout. Error counter cleared when exiting lockout.Circulator unable to start 292 Soft Lockout. Error counter cleared when exiting lockout.Circulator RPM out of range (failed wheel) 293 Soft Lockout. Error counter cleared when exiting lockout.Inducer over current 294 Soft Lockout. Send command to reset-motor. Error counter

cleared when exiting lockout.

Rollout open or previously opened 200 Wait for rollout switch to close, then enter Hard Lockout. All error counters cleared after reset. Hard

LockoutFurnace size select missing or mis-match with installed circulator motor

202 Hard Lockout. All error counters cleared after reset.

a Recycle furnace power and perform operational check. If error repeats, there may be a permanent failure on the control board.

Table 12. LED Status Codes. (Continued)

Error/Fault Condition CodeError Handling

(in addition to displaying error code) Result

Documents

69-2088—01 - S9240F1004 Modulating Hot Surface Ignition ... · S9240F1004 MODULATING HOT SURFACE IGNITION INTEGRATED FURNACE CONTROL 3 69-2088—01 INSTALLATION When Installing