L.B. White AD250(Spark Ignition) - Manual (Page 20)

SPARK IGNITION OPERATION SEQUENCE:
— Line Voltage is Sent to Transformer and to Ignition
Control
— 24 V.A.C. is sent from Transformer to the Thermostat
— A call for Heat Occurs
— Thermostat Returns 24 VAC to Ignition Control
— Red Light on Ignition Control is Illuminated
— Ignition Control Module Performs an Internal Safe Start
Check
-- Internal Components are Tested
-- Voltage is sent to Flame Sensor from Ignition
Control to Start Flame Proving Process.
-- Air Proving Switch Circuit Receives 24 Volts from
Ignition Control.
— Ignition Control Module Begins Safety Lockout Timing
— Ignition Control Module Starts Fan Motor for Prepurge
-- Air Proving Switch is Checked for Proper Operation.
-- Air Proving Switch closes and 24 Volts is returned
to Ignition Control.
— Ignition Control Powers the Igniter and Igniter Sparks.
— Ignition Control Sends 24 Volts to Gas Control through
High Limit Switches.
— Ignition Occurs
-- Igniter Continues to Spark until Flame Proving
Occurs.
-- Igniter Spark is Discontinued
-- Gas Valve Stays Open
— Room Warms to Desired Temperature
-- Thermostat is Satisfied
-- Heater Shuts Down
— Process Begins Again on Call for Heat
MULTIPLE IGNITION TRIAL SEQUENCE
— First Trial for Ignition Takes Approximately 10 Seconds
— Two More Trials for Ignition will Occur
-- Second and Third Trial Follow Immediately if First
Trial Fails
— Module Starts a 15 Minute “Wait” Period to Allow
Ignition Interruption to Pass
— Ignition Control Repeats 3 Ignition Attempts After 15
Minute Wait Period
— If Ignition Control Module Does Not Prove Flame After
Third Trial, the Module Goes into Safety Lockout (3 Flash
Pattern)
-- Igniter Shuts Down
-- Fan Motor Stops
-- Gas Valve Closes
— To Manually Reset the Ignition System
-- Unplug the Heater and Plug it back in
-- OR --
-- On heaters so equipped, turn power supply switch
to “Off” and then to “On”
-- OR --
-- Turn Thermostat to “Off” or “No Heat” and Then
Back to Above Room Temperature
Troubleshooting Instructions
19