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Troubleshooting: Fan operating sequence
Action System Response
Thermostat calls for heat.
(W terminal is energized.)
Oil primary control is energized.
Ignition system and oil primary control start the furnace. Oil flows as long as cad cell
senses flame.
Burner motor is energized and heat fan on delay timing (1 to 30 seconds) begins. When
timing is complete, the circulating fan is energized at heat speed and warm air is deliv-
ered to the controlled space.
Thermostat ends call for heat.
(W terminal is de−energized.)
Oil primary control is de−energized, terminating the burner cycle.
Heat fan off delay timing (60 to 120 seconds) begins. When timing is complete, the circu-
lating fan is de−energized.
Burner fails to light. Oil primary control locks out within lockout timing (timing depends on oil primary control).
Burner motor is de−energized.
If heat fan has started, it continues through the delay off period.
Established flame fails. Burner motor is de−energized and oil primary control goes into recycle mode.
If selected heat fan off delay is longer than the recycle delay timing, the heat fan contin-
ues to run through the next trial for ignition.
Thermostat begins call for cool.
(G and Y terminals are energized.)
Circulating fan is energized at the cool speed.
Cooling compressor turns on immediately.
Thermostat ends call for cool.
(G and Y terminals are de−energized.)
Circulating fan and cooling compressor turn off immediately.
Thermostat begins call for fan.
(G terminal is energized.)
Circulating fan is energized immediately at cool speed.
Thermostat ends call for fan.
(G terminal is de−energized.)
Circulating fan is de−energized.
Limit switch string opens. Oil primary control shut off the burner.
Circulating fan is energized immediately at heat speed.
Oil primary control is de−energized.
Circulating fan runs as long as limit string stays open.
If there is a call for cooling or fan, the circulating fan switches from heat speed to cool
speed.
Limit switch string closes. Circulating fan turns off after the selected heat fan off delay timing.
Oil primary control is de−energized.
Oil primary control is energized, initiating burner light off.
Continuous circulating fan is connected.
(Optional connectors are available for separate circu-
lating fan speed tap.)
Circulating fan is energized at low speed when there is no call for heat, cool or fan.
Humidity control is connected.
(Optional connectors are available for 120 Vac humidi-
fier.)
Humidifier connections are energized when the burner motor is energized.
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