Operation And Service - Dunkirk D247 Installation Instructions Manual

OPERATION AND SERVICE
S8600 FUNCTIONS AND OPERATION
The S8600 control module performs the following basic
functions:
SYSTEM TROUBLESHOOTING
Start the system by setting the thermostat or controller
above room temperature and observe the system response.
1 . Opens and closes the first (pilot) operator of the gas
valve.
2. Provides a spark for igniting pilot burner.
3. Senses the pilot burner flame.
4. Shuts off the spark after pilot flame is lit.
5. Opens and closes the second (Main) operator.
These functions occur in two stages - trial for pilot ignition
and main burner operation as described below.
TRIAL FOR PILOT IGNITION
On every call for heat (System start), the $8600 performs
an internal safe-start check. Ifa flame simulating condition
is present, the system will not start.
Establish the type of system malfunction or deviation from
normal operation by using the $8600 Intermittent Pilot
System Troubleshooting Table, page 23.
Use the table by following the questions in the boxes. If the
condition is true (answer is yes), go down to next box. If
the condition is not true (answer is no), go to the box
alongside.
Continue checking and answering conditions in each box
until a problem and/or the repair is explained. Use the
Component Checks section, see below, as necessary, to
perform system checks.
After any maintenance or repair, the troubleshooting
sequence should be repeated until the procedure ends with
normal system operation.
During a normal start, the $8600 opens the first (pilot) valve
operator of the gas control, which allows gas to flow to the
pilot burner. At the same time, the electronic spark
generator in the $8600 produces a 15,000 volt spark pulse
output (open circuit). This voltage produces a spark at the
igniter sensor rod which ignites the pilot burner. If the pilot
flame does not light or the presence of the pilot flame is not
detected back through the flamerod, the $8600 will not open
the second (Main) valve operator of the gas control. The
$8600F will continue to try to ignite the pilot burner until
either a flame is detected or the thermostat (controller) is
set down below a call for heat.
COMPONENT CHECKS
CHECK SPARK IGNITION CIRCUIT
The Electronic module and step-up transformer in the
$8600 provides spark ignition at 15,000 V (open circuit).
This circuit can be checked at the $8600 module as follows:
.
2.
Turn off manual gas cock to prevent the flow of gas.
Disconnect the ignition cable at the $8600 stud ter
minal to isolate the circuit from the pilot burner/
igniter-sensor, and prepare a short jumper lead using
heavily insulated wire, such as ignition wire.
MAIN BURNER OPERATION
When the pilot flame is established, a flame rectification
circuit is completed to the burner ground. The $8600 flame
sensing circuit detects the flame current, shuts off the spark
generator and opens the second (Main) valve operator to
allow gas to flow to the main burners. The pilot flame ignites
the main burner conventionally.
IMPORTANT
The electronic $8600 control module cannot be repaired.
If the troubleshooting procedure indicates a malfunction in
the $8600, the S8600 must be replaced. Intermittent Pilot
systems should be serviced only by trained, experienced
service technicians.
.
Energize the $8600 and touch one end of the jumper
firmly to the $8600 ground terminal (GND). (Do not
disconnect the existing ground lead.) Move the free
end slowly toward the stud terminal to establish a spark
and then pull the lead wire slowly away from the stud.
Not the length of the gap at which arcing discontinues.
An arc length of 1/8 inch (3.2 mm) or more indicates
satisfactory voltage output. If no arc can be established
or the maximum gap is less than 1/8 inch (3.2 ram)
fuse was okay, and power to the S8600 input terminal
was proved, replace the $8600.
PRELIMINARY CHECK
The following visual checks should be made before
troubleshooting and after maintenance.
1. Check power switch.
2. Manual shutoff cocks in the gas line to the boiler must
be open.
CAUTION
DO NOT TOUCH EITHER END OF JUMPER
OR STUD TERMINAL. THIS IS A VERY
HIGH VOLTAGE CIRCUIT AND
ELECTRICAL SHOCK CAN RESULT.
3. Make sure all wiring connections are clean and tight.
4. Review the $8600 normal sequence of operation.
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