Page 9
Once the rst stage prove switch is determined to be open,
the combustion air inducer is energized on low (rst stage)
heat speed. When the dierential in the prove switch is
great enough, the prove switch closes and a 15-second
pre-purge begins.
NOTE - During abnormal conditions such as low supply
voltage or low outdoor temperatures and the low re pres-
sure switch does not close, the combustion air inducer will
switch to high re. After a 15 second pre-purge the high
re pressure switch will close and the unit will begin op-
eration on high re. After 10 to 20 seconds of high re
operation the unit will switch to low re.
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 energiz-
es during the trial until ame 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 ve 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.
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 re on rst-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 secondstage
heat.
While in the two-stage thermostat mode (two DIP switch
setting) the burners will re on rst-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 rst and second stage
heat, the unit will re an rst stage heat and switch to sec-
ond stage heat after 30 seconds of operation. See Se-
quence of Operation ow 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 Combustuion Air Inducer
Neutral
5 Ignitor Neutral
TABLE 2
SureLight
®
Control 12 Pin Terminal Designation
PIN# Function
1 Gas Valve High Fire
2 Second Stage Prove Switch
3 Rollout In
4 Ground
5 24V Hot
6 Primary Limit In
7 Gas Valve Low Stage
8 Gas Valve Common
9 24V Neutral
10 Ground
11 Rollout Switch Out
12 1st Stage Prove Switch
TABLE 3
SureLight
®
Control 6 Pin Terminal Designation
PIN# Function
1 Data Input From Motor
2 Common
3 Not Used
4 Data Output To Motor
5 5 Volt Bias Supply
6 Not Used
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