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Reset From Lockout
Manual reset of the S8921D lockout can be accomplished
at any time by manually cycling the system thermostat (or
controller) or by cycling power to the appliance. The
S8921D also has an automatic recycle feature that
reinitiates a normal ignition cycle (five trials for ignition) one
hour after lockout, as long as the initial call for heat
continues. All safety and timing functions are in place
during the repeated ignition cycle.
MAINTENANCE
WARNING
Fire Or Explosion Hazard.
Can Cause Property Damage,
Severe Injury, Or Death.
Do not attempt to take apart the module or to clean
it. Improper assembly and cleaning can cause
unreliable operation.
Regular preventive maintenance is important in applica-
tions that place a heavy load on system controls such as
those used in the commercial cooking and agricultural
and industrial industries because:
• In many such applications the equipment operates
100,000 to 200,000 cycles per year. Such heavy
cycling can wear out the gas control in one to two
years.
• Exposure to water, dirt, chemicals and heat can
damage the gas control and shut down the control
system. A NEMA 4 enclosure can reduce exposure to
environmental contaminants. See Electronic Ignition
Service manual, 70-6604.
The maintenance program should include regular
checkout of the system as outlined in the Startup and
Checkout section, and checkout of the control system as
described in the appliance manufacturer literature.
Maintenance frequency must be determined individually
for each application. Some considerations are:
• Cycling frequency. Appliances that may cycle 20,000
times annually should be checked monthly.
• Intermittent use. Appliances that are used seasonally
should be checked before shutdown and again before
the next use.
• Consequence of unexpected shutdown. Where the
cost of an unexpected shutdown would be high, the
system should be checked more often.
• Dusty, wet, or corrosive environment. Since these
environments can cause the gas control to deteriorate
more rapidly, the system should be checked more
often.
S8921D HOT SURFACE IGNITION MODULE
Any control should be replaced if it does not perform
properly on checkout or troubleshooting. In addition,
replace any module if it is wet or looks like it has ever been
wet. Protective enclosures, as described in the Planning
the Installation section, are recommended regardless of
checkout frequency.
TROUBLESHOOTING
IMPORTANT:
1.
The following service procedures are
provided as a general guide. Follow appli-
ance manufacturer service instructions if
available.
2.
Meter readings between gas control and
ignition module must be taken within the trial
for ignition period. Once the ignition module
shuts off, wait for retry or reset at the
thermostat.
3.
If any component does not function properly,
make sure it is correctly installed and wired
before replacing it.
4.
The ignition module cannot be repaired. If it
malfunctions, replace it.
5.
Only trained, experienced service techni-
cians should service hot surface ignition
systems.
6.
After servicing, verify proper system
operation.
Perform the checkout steps in the Startup and Checkout
section as the first step in troubleshooting. Then check the
troubleshooting sequence (Fig. 4) to pinpoint the cause of
the problem.
After troubleshooting, perform the checkout procedure
again to be sure the system is operating normally.
7
69-0924—2
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