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T
T
R7997
INTEGRATED
OIL PRIMARY
WITH BLOWER
DELAY
AIR FLOW
SWITCH
Fig. 5. ST7997 Oil Burner Mounted Electronic Fan Timer airflow switch and power vent motor for
Mode
Constant circulating fan is
OPTIONS
connected. (Optional connectors are
available for separate circulating fan
speed tap.)
Electronic air cleaner is connected.
(Optional connectors are available
for 120 Vac electronic air cleaner.)
Humidity control is connected.
(Optional connectors are available
for 120 Vac humidifier.)
ST7997 OIL BURNER MOUNTED ELECTRIC FAN TIMER
HUMIDIFIER
EAC
LIMIT
(LINE
VOLTAGE)
OIL
VALVE
power venting wiring.
Table 1. ST7997 Wiring Options.
Action
CIRCULATOR
BLOWER
F1
C
HEAT CALL
LIMIT
CONTROL
ISOLATION
ELECTRONICS
K1
POWER
BURNER
VENT
MOTOR
MOTOR
System Response
a.
Circulating fan is energized at low speed when there is
no call for heat, cool or fan.
b.
If fan operation is required by a call for heat, cool or
fan, the ST7997 switches off the continuous fan speed
tap before energizing the other fan speed.
Electronic air cleaner (EAC) connections are energized when
the heat or cool speed of the circulating fan is energized.
EAC connections are not energized when the optional
continuous fan terminal is energized.
NOTE: If continuous fan option is selected, connect EAC
to line voltage input (L1).
Humidifier connections are energized when burner motor is
energized on standard models and when oil valve is
energized on purging models.
5
R
W
RC
RC
C
G
G
RC
G
Y
Y
Y
THERMOSTAT
5-WIRE
K2
OEFT
ST7997
COMPRESSOR
CONTACTOR
L2
L1
GND
J-BOX
SCREW TERMINAL
1/4 IN. QUICK CONNECT
M12923
69-1204
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