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CONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATION
SURELIGHT CONTROL
LED: SLOW FLASH RATE REMAINS
UNCHANGED THROUGHOUT SEQUENCE.
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN AT ACB
LOW SPEED. ACC. TERMINAL IS ENERGIZED.
THERMOSTAT CALLS FOR HEAT (W).
THERMOSTAT CALLS FOR COOLING.
BOARD NO. 63K8901
SYSTEM FAN DE−ENERGIZED. SYSTEM FAN
ENERGIZES ON ACB HEAT SPEED AFTER
NORMAL DELAY.
THERMOSTAT OPENS. COMBUSTION AIR
AND HTG ACC TERMINAL DE−ENERGIZE.
SYSTEM FAN SWITCHED TO ACB COOL
SPEED. ACC. TERM. REMAINS ON.
THERMOSTAT OPENS.
BOARD 63K89: SYSTEM FAN OFF. ACC. TERM.
OFF. (AFTER OFF DELAY COMPLETED).
MANUAL FAN SELECTION MADE AT THERMOSTAT.
CONTROL (G) ENERGIZES SYSTEM FAN AT ACB
LOW SPEED. ACC. TERM. ENERGIZED.
NO YES
YES
NO
HTG ACC. TERM. ENERGIZES
WITH COMB. AIR BLOWER.
BOARD NO. 24L85, 56L83, 97L48
SYSTEM FAN SWITCHES TO ACB HEAT SPEED
AFTER NORMAL DELAY (fan remains energized)
BOARDS 24L85, 56L83 AND 97L48:
SYSTEM FAN SWITCHES TO
LOW SPEED AFTER NORMAL DELAY.
(fan remains energized)
C−Heating Sequence of Operation
1 − When there is a call for heat, W1 of the thermostat en-
ergizes W of the furnace control with 24VAC.
2 − S10 primary limit switch and S47 rollout switch are
closed. Call for heat can continue.
3 − Surelight control energizes combustion air blower B6.
Combustion air blower runs until S18 combustion air
prove switch closes (switch must close within 2−1/2
minutes or control goes into 5 minute Watchguard
Pressure Switch delay). Once S18 closes, a 15−sec-
ond pre−purge follows.
4 − Surelight control energizes ignitor. A 20−second
warm−up period begins.
5 − Gas valve opens for a 4−second trial for ignition.
6 − Flame is sensed, gas valve remains open for the heat
call.
7 − After 45−second delay, Surelight control energizes in-
door blower B3.
8 − When heat demand is satisfied, W1 of the indoor ther-
mostat de−energizes W of the Surelight control which
de−energizes the gas valve. Combustion air blower
B6 continues a 5−second post−purge period, and in-
door blower B3 completes a selected OFF time delay.
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