Page 8
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 thermostat
selection is made using a DIP switch and must be posi
-
tioned 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 burners
will always fire on first-stage heat. The combustion air in
-
ducer will operate on low speed and indoor blower will
operate on low heat speed. The unit will switch to second
stage heat after a “recognition period”. DIP switch 2, la
-
beled 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 op
-
erate 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 sec
-
onds of operation. 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
