Honeywell ST9103A - Manual (Page 5)

S9103A ELECTRONIC FAN TIMER
5 69-0771B
ST9103 Operating Sequence (Continued).
Action System Response
Thermostat ends call for fan.
(G terminal is de-energized.) • Circulating fan is de-energized.
Limit switch string opens. • Oil primary control shuts off burner.
• Circulating fan is energized immediately at heat speed.
• ST9103A opens oil primary control T-T connections.
• 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. • ST9103A begins heat fan off delay sequence.
• Circulating fan turns off after the selected heat fan off delay timing.
• ST9103A recloses oil primary control T-T connections.
• Oil primary control is energized, initiating burner light off.
Continuous circulating fan is connected.
(Optional connectors are available for
separate circulating fan speed tap.) • Circulating fan is energized at low speed when there is no call for heat,
cool or fan.
• If fan operation is required by a call for heat, cool or fan, the ST9103A
switches off the continuous fan speed tap before energizing the other
fan speed.
Electronic air cleaner is connected.
(Optional connectors are available for 120
Vac electronic air cleaner.) • 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.
Humidity control is connected.
(Optional connectors are available for 120
Vac humidifier.) • Humidifier connections are energized when burner motor is energized.