S9200U1000 UNIVERSAL HOT SURFACE IGNITION INTEGRATED FURNACE CONTROL
13
69-2075EF—01
CHECKOUT
Check out the control system:
— At initial installation of the appliance.
— As part of regular maintenance procedures.
— As the first step in troubleshooting.
— Any time work is done on the system.
LED Indicators
The S9200U1000 provides three indicating LEDs; see
Fig. 4 on page 9 for location on board:
—
Flame - Amber:
indicates flame status
—
Status - Red:
indicates general system status and
error codes.
—
E-COM - Green:
indicates EnviraCOM™ bus
activity
See “Troubleshooting” on page 19 for information about
specific flash codes as referenced in the checkout
procedures.
Use the following procedures only for the integrated
furnace control; see individual component instructions for
additional checkout procedures.
I. CHECK NORMAL
OPERATION
Check Conventional 24 Vac
Thermostat
1.
Turn on power to the appliance.
2.
After power is switched on, the furnace control can
accept a W request after approximately 20 sec-
onds, and Y and G requests after approximately 10
seconds.
3.
Set the thermostat to call for heat. Make sure the
S9200U1000 control sequences the system as indi-
cated in Fig. 9 on page 17.
4.
Set the thermostat below the room temperature to
end the call for heat. The burner should go out; the
induced draft fan should provide Postpurge time (15
seconds); and after the delay time, the indoor fan
should stop.
There are three modes of operation. They are discussed
in this next section in the following order:
1.
Normal Heat Mode
2.
Normal Cooling Mode – see page 14
3.
Fan Mode – see page 14
Normal Heat Mode
Refer to Fig. 9 on page 17 for the Heat Mode control
sequence diagram. The following describes the operation
during a call for heat and the heat cycle.
Call for Heat
A call for heat is signaled by the thermostat closing the
contacts between R/2 and W or an EnviraCOM™ heat
demand. Requests for heat are ignored if there is a call for
cooling at the Y terminal.
Upon a call for heat:
— The S9200U1000 conducts a safe start check that
consists of an internal hardware/software self-
check and verification there is no main burner
flame present.
— The S9200U1000 verifies the Limit and Rollout
switch circuits are closed.
— The S9200U1000 verifies the pressure switch cir-
cuit is open.
— The S9200U1000 energizes the inducer.
— After the Pressure Switch closes, Prepurge
begins.
— After the completion of Prepurge, the HSI is ener-
gized for the Igniter Warm-up Period.
— When the Igniter Warm-up Period expires, the gas
valve is energized and the Trial for Ignition begins.
— During the Ignition Activation Period, both the HSI
element and the gas valve remain energized.
— After Ignition Activation, the HSI is de-energized
and the gas valve remains energized for the
Flame Recognition Period.
— The Heat Fan On Delay is started upon entering
Trial for Ignition.
— When flame is sensed during Trial for Ignition, the
S9200U1000 de-energizes the HSI and proceeds
to normal run mode operation.
— Once the Heat Fan On Delay has expired, the cir-
culator is energized on heat speed.
Call for Heat Satisfied
When the call for heat has ended:
— The gas valve is de-energized.
— The Postpurge and circulator fan off delay timings
begin when the loss of flame is detected.
— The inducer is de-energized when the Postpurge
Period is completed.
— The circulator is de-energized when the circulator
fan off delay has expired.
Ignition Retry
When flame is not sensed during the Trial for Ignition or is
lost less than 10 seconds after exiting Trial for Ignition:
— The gas valve is de-energized.
— The inducer remains energized during the Inter-
purge Period.
— When the Interpurge Period expires, a new Trial
for Ignition is started again for up to a maximum of
two additional trials.
— After the third Trial for Ignition has failed to light
the burner, the S9200U1000 proceeds to the Inter-
purge Period followed by the Soft Lockout, where
it remains for the Auto Restart Delay before begin-
ning another set of ignition sequences.
— The retry count is cleared if flame is sensed for
longer than 10 seconds after exiting Trial for Igni-
tion.
Ignition Recycle
When flame is established during Trial for Ignition,
maintained for at least 10 seconds, and then lost:
— The gas valve is de-energized.
— The inducer remains energized during the Inter-
purge Period.
— A new Trial for Ignition is started when the Inter-
purge Period expires.
— A maximum of three recycles are allowed on a sin-
gle call for heat before the control proceeds to Soft
Lockout. The recycle count is not cleared until the
current demand for heat is satisfied or the
S9200U1000 has just exited Soft Lockout or the
S9200U1000 is in run mode continuously for one
hour.
