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29733 R2 06/01/2003
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TABLE C-1: ST9103 DETAILED SEQUENCE OF OPERATION
Mode Action System Response
HEAT
Thermostat calls for heat.
("W" terminal is energized).
a. ST9103 closes oil primary control T - T connections).
b. Ignition system and R7184 oil primary control start the furnace.
Oil flows as long as the oil primary control senses flame.
c. Burner motor is energized and heat "fan on" delay timing
begins. When timing is complete (30 seconds), the circulator
fan is energized at heat speed.
Thermostat ends call for heat.
("W" terminal is de-
energized).
a. R7184 oil primary control is de-energized, terminating the
burner cycle.
b. Heat "fan off" delay timing begins. Length of delay depends on
ST9103 dip switch settings. When timing is complete, the
circulator fan is de-energized.
c. ST9103 returns to standby mode, (Oil primary control and
circulator fan are off, unless continuous fan operation is
selected at the thermostat).
Burner fails to light.
a. Oil primary control locks out within lockout timing, (30
seconds).
b. Burner motor is de-energized. (even though thermostat is still
calling for heat).
c. If circulator fan has started, it continues through the selected
heat “fan off” delay period.
Established flame fails.
a. Burner motor is de-energized and oil primary control goes into
recycle mode.
b. If the selected heat “fan off” delay timing is longer than the
recycle delay timing, the circulator fan continues to run through
the next trial for ignition.
COOL
Thermostat begins call for
cool. (G and Y terminals are
energized).
a. Cooling contactor is energized immediately.
b. Circulator fan is energized at cool speed.
Thermostat ends call for cool.
(G and Y terminals are de-
energized).
a. Cooling contactor is de-energized immediately.
b. Circulator fan turns off immediately.
FAN
Thermostat begins call for
fan. (G terminal is energized).
a. Circulator fan is energized immediately at cooling speed.
Thermostat ends call for fan.
(G terminal is de-energized).
a. Circulator fan is de-energized immediately.
LIMIT Limit switch string opens.
a. Oil primary control shuts off burner.
b. Circulator fan is energized immediately at heat speed.
c. ST9103 opens oil primary control T - T connections.
Continued on following page.