LIAF300
ICM2 9 11
Direct Spark Ignition (DSI) control board
Features
Direct Spark Ignition (DSI) control board
Microprocessor-based
Monitorssystemtiming,trialforignition,systemswitches,amesensingand
lockout
100% lockout safety feature monitors for repeated over-temperature faults or
amelossesanddisablestheheatoperationforsafety.
Continuously monitors the gas valve output to verify the gas valve does not
turnonoroffincorrectly.
Compatible with LP or Natural Gas
LED indication for status and fault codes to aid in troubleshooting
Twinning feature allows two furnace boards to be controlled with a single
thermostat
Replaces
• Modine Spark Ignition Control 5H79749
ELECTRICAL SHOCK HAZARD!
Before installing this unit,
turn off power at the main service panel by removing the fuse or switching
theappropriatecircuitbreakertotheOFFposition.FollowallLocal,Stateand
NationalElectricalCodeswheninstallingthisdevice.
CAUTION!
Only trained personnel should install or service heating
equipment.Whenworkingwithheatingequipment,besuretoreadand
understand all precautions in the documentation, on labels, and on tags that
accompanytheequipment.Failuretofollowallsafetyguidelinesmayresultin
damagetoequipment,severepersonalinjuryordeath.
> > > CAUTION < < <
Remove Existing Control
CAUTION!
Toservicecontrol,andpriortodisconnection,labelallwires.
Failuretodosomayresultinwiringerrorsthatcancausedangerousoperation.
1. Turn thermostat to the OFF position or set it to the lowest possible setting.
2. Turn OFF the electrical supply to furnace.
3. Turn OFF the gas supply to furnace.
CAUTION!
Failure to turn off gas and electric supplies can result in explosion,
re,deathorpersonalinjury.
4. Remove the furnace blower and control access doors.
5. Disconnectthethermostatwiresandhumidierwires(ifequippedwithahumidier).
6. Disconnectthelinevoltage,blower,electronicaircleanerwires(ifequipped)and
transformer wires.
7. Remove screws and any other fasteners and the old circuit board.
8. Examine the control and the control box for water stains.
9. Makerepairsifanysourcesofwaterleakagearefound.Besuretocheckhumidiers,
evaporator coils and vent systems in the area of the control.
Install New Control
1. Ground yourself. When handling the circuit board; hold it by the edges.
2. Fasten the circuit board with the retaining screws.
3. Connect all line voltage, low voltage and accessory wires.
4.Verifythesequenceofoperation.
Sequence of Operation
When a call for heat is made by connecting the W and R terminals, the control runs through
thefollowingsequencetostartthefurnace:
• Control board ensures pressure switch is initially open
• The draft inducer motor is energized
•Theboardconrmsdraftpressurethroughclosureofthepressureswitch
• Inducer performs a 30-second pre-purge delay
• Following the inducer pre-purge delay, the gas valve & spark ignitor energize
•Gasowsintotheburnersandislitbythesparkigniter
•Theamesensorconrmsthepresenceofame
• The spark ignitor stops sparking and the gas stays on with the burners lit
•Athirty-second(30S)heatblowerpre-heatondelayisenactedtopre-heattheplenum
• Following the 30 second pre-heat delay, the heat blower turns on.
• Loss of the heat call deactivates the gas valve immediately and both the inducer and heat
blowers remain running
• The inducer performs a 60 second post–purge delay upon the loss of the heat call
• The heat blower performs a 90 second post purge following the loss of the heat call
Specifications
Input
• Line Voltage: 120 VAC, 50/60 HZ
• Control Voltage: 18 – 30 VAC, 50/60 HZ
Output
• Heat Blower: 15 FLA/30 LRA @ 120 VAC
• Inducer Fan:½HP,(9.8FLA/58.8LRA)@120VAC
• Gas Valve: 2.3A Pilot Duty @ 24 VAC
Environmental
• Operating Temperature:-40°Fto175°F(-40°Cto80°C),-40°Fto185°F(-40°Cto85°C)
Mechanical
• Dimensions: 6.0”L x 5.0”W x 3.0”D
Use caution when installing and servicing the furnace to avoid and control
electrostaticdischarge;ESDcanimpactelectroniccomponents.Theseprecautions
mustbefollowedtopreventelectrostaticdischargefromhandtoolsandpersonnel.
Following the precautions will protect the control from ESD by discharging static
electricitybuilduptoground.
1. Disconnect all power to the furnace. Do not touch the control or the wiring prior to
dischargingyourbody’selectrostaticchargetoground.
2. Togroundyourself,touchyourhandandtoolstoaclean,metal(unpainted)furnace
surface near the control board.
Electrostatic Discharge (ESD) Precautions
Flame Sense Diagnostics
Flame sensing – Thesystemwillusetheamerecticationmethodofamesensing;
usingaremoteamesensingelementconnectedtopin7oftheP1connector.Theame
sensecircuitrywilloperatecontinuously,providingignitionlockoutincaseameissensed
without the gas valve being energized.
Flame sense check – Thecontrolexpectsnormalametobewithin3-5microampsanda
sensedamesignalof1.1microampsorbelowasaweakame.Ifameissensedduring
the 7 second Ignition activation period, the spark ignitor will de-energized after 2 seconds.
Flame circuit is not sensing a ame signal – Ifthecontroldetectsaamesignalwhen
ameisnotexpected;thecontrolgoesintoa1-hourlockoutwhichengagestheinducer
and heat blowers.
Flame loss lockout – Ifatrialforignitionsucceedsandthentheamesensordetectsno
ameafterwards,thecontrolwillimmediatelyshutoffthegasvalveandactivatethemain
blower. If the pressure switch is still closed, the control will attempt another ignition trial
aftera30-secondpre-purgedelay.Ifameislost5timesinonecallforheat,thecontrol
will go into soft lockout. The inducer will turn off after a 60-second post-purge delay, and the
heat blower will turn off after 90 seconds. The status LED blinks code 7 for the duration of
lockout.
Test Mode Delay Duration (sec)
Inducer Pre-purge 5
Trial for Ignition 7
Blower-On Delay 10
Inducer Post-purge 60
Blower-Off Delay 10
5018419
3. Servicethefurnaceaftertouchingthechassis.Yourbodywillrechargewith
staticelectricityasyoushufeyourfeetormovearound,andyoumustreground
yourself.
4. Reground yourself if you touch ungrounded items.
5. Beforehandlinganewcontrol,regroundyourself,thiswillprotectthecontrol.Store
the used and new controls in separate; containers before touching ungrounded
objects.
6. ESDdamagecanalsobepreventedbyusinganESDservicekitfeetormove
around, and you must reground yourself.
Field Test Mode
Connecting the C terminal to the Test/Twin terminal and disconnecting it in less than
0.9secondsshallputthecontrolintoeldtestmode.Inthismode,pre-purgeandheat
blower delay times are reduced. Trial for ignition and inducer post-purge times remains
the same.
