Lennox G50UHi Unit Information page 11

®
5. SureLight Integrated Ignition Control
69M15 (A92)
The SureLight system consists of ignition control board (fi-
gue 9), ignitor (figure 11) and sensor (figure 12). The igni-
tion control and ignitor work in combination to ensure fur-
nace ignition and ignitor durability. The ignition control,
controls all major furnace operations. The ignition control
also features two LED lights (DS1 red and DS2 green) for
troubleshooting and two 120 volt accessory terminals
each rated at (1) one amp. A 24 volt accessory terminal
rated at 0.5 amps is also provided. Table 5 shows 24 volt
and 120 volt control terminal designations. Tables 6 and 7
show jack plug terminal designations. See table 4 for trou-
bleshooting diagnostic codes. Units equipped with the
SureLight system can be used with either electronic or
electro−mechanical thermostats without modification.
Each time power is applied to the furnace, the ignition con-
trol performs a selfcheck. The SureLight ignitor is made of
durable silicon−nitride. Ignitor longevity is also enhanced
by voltage ramping by the control board. The ignition con-
trol finds the lowest ignitor temperature which will suc-
cessfully light the burner, thus increasing the life of the ig-
nitor.
TABLE 5
IGNITION CONTROL 69M15 TERMINAL DESIGNATIONS
COOL Blower − Cooling Speed (120V)
HEAT Blower − Heating (120V)
PARK Unused blower lead not energized
FAN Continuous Low Blower Speed
EAC Accessory Terminal (120V)
XFMR
LINE
HUM Heat Only Accessory (120V)
5 Terminals
FS
24V HUM Heat Only Accessory (24V)
TABLE 6
IGNITION CONTROL 69M15 TERMINAL DESIGNATIONS
PIN #
1 Combustion Air Inducer Line Voltage
2
3 Combustion Air Inducer Neutral
4
Transformer (120V)
Input (120V)
120 Volt Neutral
Flame Sensor
FUNCTION
Ignitor Voltage
Ignitor Neutral
Page 11
INTEGRATED IGNITION CONTROL 69M15
FIGURE 9
P r o v e S w i t c h a n d L i m i t O u t
I G N I T I O N C O N T R O L 6 9 M 1 5 T E R M I N A L D E S I G N A T I O N S