Lennox G24M SERIES, Информация об устройстве, Страница: 12 / 36

Page 12
EARLY MODEL G24M FURNACE CONTROL (A3)
FIGURE 9
LINE VOLTAGE
TERMINAL
CONNECTIONS
24VAC VOLT
TERMINAL
CONNECTIONS
THERMOSTAT
CONNECTIONS
DIAGNOSTIC
LED
See Table 6 for
Terminal
Functions
FAN-OFF TIMING
SWITCHES
SPARK OUTPUT
PLUG P20
TABLE 5
Furnace Control A3 Limit Response During Operation
Response
Condition
Combustion
Air
Blower
Gas
Valve
Supply
Air
Blower
Diagnostic
LED
Loss of Flame
Sensed Before
End of 45 se-
cond Blower
On Delay
(3 or Fewer
Trials
for Ignition)
On
On
(Spark
Starts
Within 0.8
seconds)
On Fast Flash
Loss of Flame
Sensed After
45 second
Blower On
Delay (3 or
Fewer Trials
for Ignition)
On
Off Then
On With
Spark
After Pre-
Purge
On Fast Flash
Loss of Flame
Sensed (More
Than 3 Trials
for Ignition)
Off Off Off 2 Flashes
Flame Sensed
Without
Demand
On Off On 5 Flashes
Primary or
Secondary
Limit Open
On Off On 4 Flashes
Rollout Switch
Open
On Off On 4 Flashes
Combustion
Air Prove
Switch Open
On Off On 3 Flashes
When flame is sensed, the indoor blower starts after a
45 second delay. Gas valve remains open and blower
continues to run until demand stops, flame sensor
senses loss of flame, a limit opens or the prove switch
opens. If any of these events occur during a thermo-
stat demand, the gas valve closes and the diagnostic
LED registers the error condition (table 5).
Blower Control and Timings
DANGER
Electrical Shock Hazard.
This control contains field adjustable switches
and also contains line voltage. Make sure power
is disconnected before making any field adjust-
ments or performing any service procedure.
NOTE—If fan “off” time is set too low, residual heat
in heat exchanger may cause primary limit S10 to
trip resulting in frequent cycling of blower. If this
occurs, adjust blower to longer time setting.
Fan “ON” timing (time that the burners operate before
the supply air blower starts) is fixed at 45 seconds and
cannot be adjusted.
Fan “OFF” timings (time that the blower operates after
a heating or cooling demand has been satisfied) are de-
termined by the arrangement of switches on the fur-
nace control board. See figure 9. To adjust fan “off ”
timings, gently reposition the switches to a new timing