Lennox G32 SERIES, Информация об устройстве

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Page 11
WARNING
Shock hazard.
Disconnect power before servicing. Integrated
Control Board is not field repairable. If control is
inoperable, simply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
8. Two Stage Integrated Control Board(A92)
All G32−5 units units are equipped with the Lennox two−
stage integrated SureLight control board. The system
consists of a ignition control board (figure 14 with control
terminal designations in tables 7, 8 and 9) and ignitor (fig
ure 9). The board and ignitor work in combination to en
sure furnace ignition and ignitor durability. The board con
trols all major furnace operations. The board features two
LED lights, DS1 and DS2 for troubleshooting. The board
also has two accessory terminals rated at (1) one amp
each. See table 10 for troubleshooting diagnostic cod
es.
Electronic Ignition
At the beginning of each heat cycle, SureLight control mon
itors the first stage and second stage combustion air induc
er prove switch. The control will not begin the heating cycle
if the first stage prove switch is closed (by−passed). Like
wise the control will not begin the second stage heating
cycle if the second stage prove switch is closed and will al
low first stage heat only. However if the second stage prove
switch closes during the first stage pre−purge, the control
will still respond to second stage heat. Once the first stage
prove switch is determined to be open, the combustion air
inducer is energized on low (first stage) heat speed. When
the differential in the prove switch is great enough, the
prove switch closes and a 15−second pre−purge begins. If
the switch is not proven within 2−1/2 minutes, the control
goes into Watchguard−Pressure Switch mode for a 5−min
ute re−set period.
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.
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 14), 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 field se
lectable 10 or 15 minute delay (dip switch 3), the unit will
switch to second stage heat. While in the two−stage ther
mostat mode (
two jumper 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 W1 and W2 (first and second stage heat) the unit will fire
on first stage heat and will 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 5 for dip switch settings.