Spark Ignition Circuit - Honeywell S8700 Series Installation Instructions Manual

S8700B,D-F,J-M DIRECT SPARK IGNITION CONTROLS
— Make certain that the S8700 is not in safety lockout.
De-energize the system by moving the temperature
control setpoint below the room temperature or
remove power to the S8700 control. Wait at least five
seconds and reenergize the system by moving the
temperature control setpoint 5°F (3°C) above the
room temperature. Reapply 24 Vac power to the
S8700 control.
— Check the ceramic insulator on the flame sensor,
spark igniter or igniter/sensor. A cracked insulator
allows current to leak to ground. Replace the device
if the insulator is cracked.
— Check the flame sensor and its mounting bracket.
Flame sensor must be held firmly in place and be
positioned in the most flame per the appliance
manufacturer specifications. Repair or replace as
necessary. Correct the position if it is bent out of
shape.
— Review the S8700 normal sequence of operation.
See the Start System section.
START
CALL FOR HEAT (24 VAC INPUT TO 24 VAC TERMINAL).
SAFE START
SAFE START CHECK. FLAME DETECTED?
CHECK/
(LED BLINKS RAPIDLY).
PREPURGE
PREPURGE (J AND K MODELS)
TRIAL FOR
SPARK GENERATOR POWERED; MAIN VALVE OPENS.
IGNITION
MAIN BURNER LIGHTS AND FLAME SENSED
DURING TRIAL FOR IGNITION?
MAIN
NORMAL MAIN BURNER OPERATION.
BURNER
OPERATION
FLAME SIGNAL LOST?
CALL FOR HEAT ENDS (24 VAC INPUT REMOVED
FROM 24 VAC TERMINAL).
MAIN BURNER OFF.
END
NOTES:
— WHEN CONTROL IS IN LOCKOUT, ALARM OUTPUT (IF PROVIDED) IS ENERGIZED.
— LED FLASHES AT HEARTBEAT SPEED DURING ALL NORMAL OPERATION.
69-1299
NO
YES
NO
Fig. 4. S8700B,D,J,K one-trial sequence of operation.
S8700 COMPONENT CHECKS

Spark Ignition Circuit

The S8700 provides high voltage spark energy to light
the main burner. To check the spark ignition circuit, do
the following:
1. Shut off the gas supply to the gas control.
2. Be sure system power supply delivers proper volt-
age to the S8700 during the ignition cycle.
3. Disconnect the ignition cable at the S8700 spark
terminals to isolate the circuit from the spark igniter
or igniter sensor. Prepare a short jumper lead,
using heavily insulated wire such as ignition cable.
WAIT 4 SEC. FLAME
YES YES
STILL DETECTED?
NO
MAIN VALVE CLOSES;
NO
SPARK GENERATOR OFF.
LOCKOUT WITH LED ON STEADY.
MAIN VALVE STAYS OPEN;
YES
SPARK GENERATOR POWERED.
MAIN BURNER LIGHTS AND FLAME
SENSED DURING TRIAL FOR IGNITION?
NO
6
LOCKOUT WITH
LED ON STEADY.
YES
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