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TABLE 7
SureLight BOARD J156 (J2) TERMINAL
DESIGNATIONS
PIN # FUNCTION
1 Ignitor
2
Not Used
3
Ignitor Neutral
4
Combustion Air Blower Line Voltage
5
Not Used
6
Combustion Air Blower Neutral
TABLE 8
SureLight BOARD J58 (J1) TERMINAL
DESIGNATIONS
PIN # FUNCTION
1 Primary Limit In
2
Gas Valve Common
3
Roll Out Switch Out
4
Gas Valve 24V
5
Pressure Switch In
6
Pressure Switch and Primary Limit Out
7
Not Used
8
Roll Out Switch In
9
Ground
CAUTION
Electrostatic discharge can affect electronic
components. Take precautions during furnace
installation and service to protect the furnace’s
electronic controls. Precautions will help to
avoid control exposure to electrostatic dis-
charge by putting the furnace, the control and
the technician at the same electrostatic poten-
tial. Neutralize electrostatic charge by touching
hand and all tools on an unpainted unit surface,
such as the gas valve or blower deck, before per-
forming any service procedure.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
a-Electronic Ignition
On a call for heat the SureLight control monitors the com-
bustion air blower pressure switch. The control will not be-
gin the heating cycle if the pressure switch is closed (by-
passed). Once the pressure switch is determined to be
open, the combustion air blower is energized. When the
differential in the pressure switch is great enough, the
pressure switch closes and a 15-second pre-purge be-
gins. If the pressure switch is not proven within 2-1/2 min-
utes, the control goes into Watchguard-Pressure Switch
mode for a 5-minute re-set period.
After the 15-second pre-purge period, the SureLight igni-
tor warms up for 20 seconds after which the gas valve
opens for a 4-second trial for ignition. G23X units
equipped with board 24L85, 56L83 or 63K89: the ignitor
stays energized for the first second of the 4-second trial.
Units equipped with board 97L48: ignitor stays energized
duringthe trial until flame is sensed.If ignition is not proved
during the 4-second period, the control will try four more
times with an inter purge and warm-up time between trials
of 35 seconds. After a total of five trials for ignition (includ-
ing the initial trial), the control goes into Watchguard-
Flame Failure mode. After a 60-minute reset period, the
control will begin the ignition sequence again.
The SureLight control board has an added feature that
prolongs the life of the ignitor. After a successful ignition,
the SureLight control utilizes less power to energize the ig-
nitor on successive calls for heat. The control continues to
ramp down the voltage to the ignitor until it finds the lowest
amount of power that will provide a successful ignition. It
finds this by ramping down until the ignitor will not light,
then steps up the amount of power by three times. This
amount of power is used for 255 cycles. On the 256th call
for heat, the control will again ramp down until the lowest
power is determined and the cycle begins again.
b-Fan Time Control
The fan on time of 45 seconds is not adjustable. Fan off
time (time that the blower operates after the heat demand
has been satisfied) can be adjusted by flipping the dip
switches located on the SureLight integrated control. The
unit is shipped with a factory fan off setting of 90 seconds.
Fan off time will affect comfort and is adjustable to satisfy
individual applications. See figure 22.
FIGURE 22
FAN-OFF TIME ADJUSTMENT
To adjust fan-off timing, flip dip switch to desired setting.
60sec. 90sec. 120sec. 180sec.
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