14
OPERATION
Module operation can be conveniently divided into two
phases for S8610 and three for S8670. The phases are:
•
Prepurge (S8670 only)
•
T
rial for ignition (all models)
•
Main burner operation (all models)
Figs. 12 and 13 summarize the normal operating se-
quences of the modules.
PREPURGE (S8670 ONLY)
On proof of airflow, the air proving switch closes and
energizes the S8670. When the module is used in an
atmospheric system, the call for heat energizes the module.
In either case, the module first initiates a 45 second.
delay to allow system prepurge. After prepurge, the module
starts the pilot ignition sequence.
Fig. 12—S8610 normal operating sequence.
START
THERMOSTAT (CONTROLLER)
CALLS FOR HEAT
SPARK GENERATOR POWERED
First valve (pilot) operator opens
PILOT BURNER OPERATION
Pilot burner lights.
Module senses
flame current.
Pilot burner does not light.
Module Response
Shutoff/lockout timing is stamped on modulea
Ignition spark continues, pilot
valve remains open until system
is reset
S8610A,F
S8610B,H
a
STAGE 1
TRIAL FOR
IGNIITION
STAGE 2
MAIN BURNER
OPERATION
END
MAIN BURNER OPERATION
Module monitors pilot flame
current.
THERMOSTAT (CONTROLLER)
SATISFIED
Valves close, pilot and main
burners are off.
POWER INTERRUPTION
System shuts off, restarts when power is
restored.
PILOT FLAME FAILURE
Main valve closes.
Module starts trial for ignition.
1
FLAME CURRENT SENSED
Spark generator off.
Second valve operator (main)
opens.
•
•
2
3
4
5
6
1
OR
After 15 or 90 seconds
maximum system locks out;
must be manually reset.
M549
13
69-0523
CHECKOUT
Check out the gas control system:
•
A
t initial installation of the appliance.
•
As part of regular maintenance procedures. Mainte-
nance intervals are determined by the application.
See PLANNING THE INSTALLATION, page 1, for
more information.
•
As the first step in troubleshooting.
•
Any time work is done on the system.
WARNING
FIRE OR EXPLOSION HAZARD
MAY CAUSE PROPERTY DAMAGE, SEVERE
INJURY, OR DEATH
1.
If you smell gas or suspect a gas leak, turn off
gas at manual service valve and evacuate the
building. Do not try to light any appliance, do
not touch any electrical switch or telephone in
the building until you are sure no spilled gas
remains.
2.
Gas leak test must be done as described in
Steps 1 and 5 below on initial installation and
any time work is done involving the gas pip-
ing.
STEP 3: Reset the Module.
■
Turn the thermostat to its lowest setting.
■
Wait one minute.
As you do Steps 4 and 5, watch for points where operation
deviates from normal. Refer to Troubleshooting Chart to
correct problem.
STEP 4: Check Safety Shutoff Operation.
This step applies to lockout and continuous retry modules
only.
■
Turn gas supply off.
■
Set thermostat or controller above room temperature to
call for heat.
■
Watch for spark at pilot burner either immediately or
following prepurge. See device label.
■
Time spark from start to shutoff. See device label.
Ignition sequence should start again followed by shutoff
after 90 seconds maximum.
■
Open manual gas control knob and make sure no gas is
flowing to pilot or main burner.
■
Set thermostat below room temperature and wait one
minute before continuing.
STEP 5: Check Normal Operation.
■
Set thermostat or controller above room temperature to
call for heat.
■
Make sure pilot lights smoothly when gas reaches the
pilot burner.
■
Make sure main burner lights smoothly without flash-
back.
■
Make sure burner operates smoothly without floating,
lifting, or flame rollout to the furnace vestibule or heat
buildup in the vestibule.
■
If gas line has been disturbed, complete gas leak test.
GAS LEAK TEST: Paint gas control gasket edges and all
pipe connections downstream of gas control, including
pilot tubing connections, with rich soap and water solu-
tion. Bubbles indicate gas leaks. Tighten joints and
screws or replace component to stop gas leak. Recheck
with soap and water.
■
Turn thermostat or controller below room temperature.
Make sure main burner and pilot flames go out.
STEP 1: Perform Visual Inspection.
■
With power off, make sure all wiring connections are
clean and tight.
■
Turn on power to appliance and ignition module.
■
Open manual shutoff valves in the gas line to the
appliance.
■
Do gas leak test ahead of gas control if piping has been
disturbed.
GAS LEAK TEST: Paint gas control gasket edges and all
pipe connections downstream of gas control, including
pilot tubing connections, with rich soap and water solu-
tion. Bubbles indicate gas leaks. Tighten joints and
screws or replace component to stop gas leak. Recheck
with soap and water solution.
STEP 2: Review Normal Operating Sequence and Module
Specifications.
■
See OPERATION, page 13, and APPLICATION,
page 1.
