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After the 15-second pre-purge period, the SureLight ignitor
warms up for 20 seconds after which the gas valve opens
for a 4-second trial for ignition. The ignitor energizes 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 sec
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.
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 fire. After a 15 second pre-purge the high fire
pressure switch will close and the unit will begin operation
on high fire. After 10 to 20 seconds of high fire operation the
unit will switch to low fire.
Two Stage Operation / Thermostat Selection Jumper
The control can be utilized in two modes: SINGLE-STAGE
thermostat or TWO-STAGE thermostat. The thermostat
selection is made using a dip switch (figure 5) and must be
positioned for the particular application. The dip switch is
factory set to “
OFF
” for use with a two-stage thermostat
with two stage heat. Re-position dip switch to “
ON
” for use
with a single stage thermostat with two stage heat.
While in the single-stage thermostat mode (
ON
DIP switch
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 or 15
minute field selectable recognition period, the unit will
switch to second stage heat. While in the two-stage ther
mostat mode (
OFF
DIP switch setting) 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 an 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
Switch 1 -- Thermostat Selection --
This unit may be
used with either a single-stage or two-stage thermostat.
The thermostat selection is made using a DIP switch which
must be properly positioned for the particular application.
The DIP switch is factory-positioned for use with a two-
stage thermostat. If a single-stage thermostat is to be used,
the DIP switch must be repositioned.
a -
Select “OFF
” for two-stage heating operation con
trolled by a two-stage heating thermostat (factory set
ting);
b -
Select “ON
” for two-stage heating operation con
trolled by a single-stage heating thermostat. This set
ting provides a timed delay before second-stage heat
is initiated.
Switch 2 -- Second Stage Delay (Used with Single-
Stage Thermostat Only) --
This switch is used to deter
mine the second stage on delay when a single-stage ther
mostat is being used. The switch is factory-set in the OFF
position, which provides a 10-minute delay before second-
stage heat is initiated. If the switch is toggled to the ON
position, it will provide a 15-minute delay before second-
stage heat is initiated. This switch is only activated when
the thermostat selector jumper is positioned for SINGLE-
stage thermostat use.
Switches 3 and 4 -- Heating Blower-Off Delay --
The
heating blower-on delay of 30 seconds is not adjustable.
The heating blower-off delay (time that the blower operates
after the heating demand has been satisfied) can be ad
justed by moving switches 3 and 4 on the integrated con
trol. The unit is shipped from the factory with a heating
blower-off delay of 90 seconds. The heating blower off
delay affects comfort and is adjustable to satisfy individual
applications. Adjust the blower off delay to achieve a sup
ply air temperature between 90° and 110°F at the exact
moment that the blower is de-energized. Longer off delay
settings provide lower supply air temperatures; shorter set
tings provide higher supply air temperatures.Table 1 (with
figure 4) provides the blower off timings that will result from
different switch settings.
TABLE 1
Heating Blower-Off Delay Switch Settings
Blower Off Delay
(Seconds)
Switch 3
Switch 4
60
Off
On
90
(factorysetting)
Off
Off
120
On
Off
180
On
On
HEAT FAN‐OFF TIME IN SECONDS
60sec.
90sec.
120sec.
180sec.
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
To adjust fan-off timing, flip dip switch to desired set
ting.
FIGURE 4
