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After the 15-second pre-purge period, the SureLight
®
ig-
nitor warms up for 20 seconds after which the gas valve
opens for a 4-second trial for ignition. The ignitor remains
energized during the 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(including 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.
NOTE -
During abnormal conditions such as low supply
voltage or low outdoor temperatures and the low fire pres
-
sure switch does not close, the combustion air inducer will
switch to high speed. After the low & high pressure switch
close, the unit will proceed with a 15 sec pre-purge, fol-
lowed by a 20 sec ignitor warm up, then ignition on high-
fire. After 10 to 20 seconds of high fire operation the unit
will switch to low fire.
Two Stage Operation / Thermostat Selection DIP
Switch
The control can be utilized in two modes: SINGLE-STAGE
thermostat or TWO-STAGE thermostat. The thermo
-
stat selection is made using a DIP switch and must be
positioned for the particular application. DIP switch 1,
labeled T”STAT HEAT STAGE is factory-set in the OFF
position for use with a two-stage thermostat. Move the
DIP switch to ON for use with a single stage thermostat.
While in the single-stage thermostat mode, the burn
-
ers will always 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 after a “recog
-
nition period”. DIP switch 2, labeled SECOND STAGE
DELAY, is factory set in the OFF position for a 7 minute
recognition period. The switch can be moved to the ON
position for a 12 minute recognition period, after which
time the unit will switch to second-stage heat. While in the
two-stage thermostat mode, the burners will fire on first-
stage heat. The combustion 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 oper
-
ation. See Sequence of Operation flow charts in the back
of this manual for more detail.
TABLE 1
SureLight
®
Control 5 Pin Terminal Designation
Pin #
Function
1
Ignitor
2
Combustion Air Inducer High Speed
3
Combustion Air Inducer Low Speed
4
Combustion Air Inducer Neutral
5
Ignitor Neutral
TABLE 2
SureLight
®
Control 12 Pin Terminal Designation
Pin #
Function
1
Gas Valve Second Stage
2
Pressure Switch Second Stage
3
Rolout Switch
4
Ground
5
24V Hot
6
Primary Limit In
7
Gas Valve First Stage
8
Gas Valve Common
9
24V Neutral
10
Ground
11
Primary Limit Out
12
Pressure Switch First Stage
