Lennox G60UH Service Manual page 13

onds. After a total of five trials for ignition (including the ini-
tial 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 pro-
longs the life of the ignitor. After a successful ignition, the
SureLight control utilizes less power to energize the ignitor
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. 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.
Two Stage Operation / Thermostat Selection Jumper
The control can be utilized in two modes: SINGLE−STAGE
thermostat or TWO−STAGE thermostat. The thermostat
selection jumper E20, located just below dip switches 1
through 4 (figure 4), must be positioned for the particular
application. The jumper is factory set on TWO" for use
with a two−stage thermostat with two stage heat. Re−posi-
tion jumper to SINGLE" for use with a single stage thermo-
stat with two stage heat.
While in the single−stage thermostat mode (single jumper
setting), the burners will always fire on first−stage heat. The
combustion air inducer will operate on low speed and in-
door blower will operate on low heat speed. After a 10 min-
ute recognition period, the unit will switch to second stage
heat. While in the two−stage thermostat mode (two jumper
setting) the burners will fire on first−stage heat. The com-
bustion air inducer will operate on low speed and indoor
blower will operate on low heat speed. The unit will switch
to second−stage heat on call from the indoor thermostat. If
there is a simultaneous call for first and second stage heat,
the unit will fire on first stage heat and switch to second
stage heat after 30 seconds of operation. See Sequence of
Operation flow charts in the back of this manual for more
detail.
Dip Switch Settings
Dip Switches 1 and 2 − Heating Fan off Delay − The fan on
time of 45 seconds is not adjustable. Fan off time (time that
the blower operates after the heat demand has been satis-
fied) can be adjusted by flipping the dip switches 1 and 2
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. For customized comfort, monitor the supply
air temperature once the heat demand is satisfied. Note the
supply air temperature at the instant the blower is de−ener-
gized. Adjust the fan−off delay to achieve a supply air tem-
perature between 90° − 110° at the instant the blower is de−
energized. (Longer delay times allow for lower air tempera-
ture, shorter delay times allow for higher air temperature).
See table 1 for dip switch settings.
Delay (Seconds)
60
90
120
180
Switch 3 − Second Stage Delay (Used with Single−Stage
Thermostat Only) −− This switch is used to determine the
second stage on delay when a single−stage thermostat is
being used. The switch is factory−set in the ON position,
which provides a 10−minute delay before second−stage
heat is initiated. If the switch is toggled to the OFF position,
it will provide a 15−minute delay before second−stage heat
is initiated. This switch is only activated when the thermo-
stat selector jumper is positioned for SINGLE−stage ther-
mostat use.
Switch 4 − Cooling Fan off Delay − The fan on delay time
of 2 seconds is not adjustable. Fan off time (time that the
blower operates after the cool demand has been satisfied)
can be adjusted by flipping dip switch 4. The unit is shipped
with a factory fan off setting of 45 seconds. Fan off time will
affect comfort and is adjustable to satisfy individual ap-
plications. See table 2 for cool fan off time settings.
Delay (Seconds)
2
45
Diagnostic LED's (DS1 and DS2)
Two diagnostic LED'S are located on the two−stage inte-
grated control board. See figure 4. These light flashes cor-
respond with the codes detailed in table 6.
Factory Installed Jumper Y1 to Y2
A factory−installed jumper from Y1 to Y2 terminals on the
integrated control board terminal strip must be clipped for
two−stage cooling.
Page 13
TABLE 1
Heating Fan Off Delay
Switch 1
Off
Off
On
On
TABLE 2
Cooling Fan Off Delay
Switch 4
Off
On
Switch 2
Off
On
Off
On