Honeywell S8700 Series, Installation Instructions Manual

S8700B,D-F,J-M DIRECT SPARK IGNITION CONTROLS

7

69-1299

Fig. 5. S8700E,F,L,M retry sequence of operation.

WARNING

High Voltage Hazard. 
Shock can cause personal injury.
To prevent electric shock, do not allow fingers to 
touch the stripped end of the jumper or the 
spark terminal. 

4.

Perform this test immediately upon energizing the 
system, before the S8700 goes into lockout and 
interrupts the spark circuit. Touch one end of the 
jumper firmly to the S8700 GND terminal. Do not 
remove the existing ground lead. Slowly move the 
other end of the jumper wire toward the spark ter-
minal on the control to establish a spark. Pull the 
wire away from the spark terminal and note the 
length of the gap at which the spark discontinues. 

5.

A spark length of 1/8 in. (3 mm) or more indicates 
satisfactory voltage output. If no arc can be 
established or the maximum spark is less than 1/8 
in. (3 mm) and power to the S8700 input terminals 
was proved, replace the S8700.

Ignition Cable 

Check the electrical continuity of the ignition cable and 
make certain that the cable is not in contact with metal 
surfaces. The total cable length should not exceed 6 ft 
(1.8m). Check connection to the spark terminal on the 
S8700 and the boot connection to the igniter/sensor. 
Make certain they are clean and tight.

Grounding Connections

A common ground is required for the main burner, spark 
igniter mounting bracket or igniter sensor mounting 
bracket, and the GND (burner) terminal of the S8700. If 
the common ground connections are poor or erratic, 
safety shutdown can occur occasionally even though 
operation is normal at time of checkout. Therefore, if 
nuisance shutdowns have been reported, be sure to 
check ground connections. 

Electrical ground connections at the spark igniter or 
igniter sensor and the S8700 must be clean and tight. If 
leadwire is damaged or deteriorated, use only a No. 14 
or No. 18 gauge, moisture resistant, thermoplastic 
insulated wire with 221

°

F (105

°

C) minimum rating as a 

replacement.

Flame Sensor Circuit

The S8700 provides ac voltage to the flame sensor. 
When a flame of sufficient size is present, the ac 
voltage is rectified and sensed as a dc flame current by 
the S8700. The S8700 will operate with a steady 1.0 µA 
dc flame current. However, reliable appliance operation 
requires at least 2.0 µA flame current (measured with  
an analog dc microammeter during worst case appli-
ance checkout.).

CALL FOR HEAT (24 VAC INPUT TO 24 VAC TERMINAL).

SAFE START CHECK. FLAME DETECTED?
(LED BLINKS RAPIDLY).

PREPURGE (L AND M MODELS).

SPARK GENERATOR POWERED; MAIN VALVE OPENS.

MAIN BURNER LIGHTS AND FLAME SENSED 
DURING TRIAL FOR IGNITION?

NORMAL MAIN BURNER OPERATION.

FLAME SIGNAL LOST?

CALL FOR HEAT ENDS (24 VAC INPUT REMOVED
FROM 24 VAC TERMINAL).

MAIN BURNER OFF.

MAIN VALVE STAYS OPEN; 
SPARK GENERATOR POWERED.

1 HOUR AUTO RESET TIME.

START

SAFE START
CHECK/
PREPURGE

TRIAL FOR
IGNITION

MAIN
BURNER
OPERATION

END

NO

NO

NO

NO

YES

NO

YES

YES

NO

YES

YES

M16530

WAIT 4 SEC. FLAME
STILL DETECTED?

YES

LOCKOUT WITH
LED ON STEADY.

MAIN VALVE CLOSES;
SPARK GENERATOR OFF.
LOCKOUT WITH LED ON STEADY

MAIN BURNER LIGHTS AND FLAME
SENSED DURING TRIAL FOR IGNITION?

NOTES:
— WHEN CONTROL IS IN LOCKOUT, ALARM OUTPUT (IF PROVIDED) IS ENERGIZED.
— LED FLASHES AT HEARTBEAT SPEED DURING ALL NORMAL OPERATION.

RETRY COUNT
LESS THAN 2?

30 SEC. BETWEEN
TRIAL PURGE.