22
P/N 30149, Rev. G [12/15/2016]
Table C-1: 1158-120 Electronic Fan Timer Board (EFT)
Detailed Sequence Of Operati
on (BML)
Mode
Action
System Response
HEAT
Thermostat calls for heat. ("W"
terminal is energized).
EFT closes the oil primary control T - T connections.
Ignition system and the oil primary control start the furnace. Oil flows as long as the oil
primary control senses flame.
Burner motor is energized and heat "fan on" delay timing begins. When timing is complete, the
circulator fan is energized at heat speed.
Thermostat ends call for heat.
("W" terminal is de-energized).
The oil primary control is de-energized, terminating the burner cycle.
Heat "fan off" delay timing begins. Length of delay depends on EFT dipswitch settings. When
timing is complete, the circulator fan is de-energized.
EFT 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.
Oil primary control locks out within lockout timing, (15 seconds).
Burner motor is de-energized. (Even though thermostat is still calling for heat).
If circulator fan has started, it continues through the selected heat “fan off” delay period.
Established flame fails.
Burner motor is de-energized and oil primary control goes into recycle mode.
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 ener
-
gized).
Cooling contactor is energized immediately.
Circulator fan is energized at cool speed.
Thermostat ends call for cool.
(G and Y terminals are de-ener-
gized).
Cooling contactor is de-energized immediately.
Circulator fan turns off immediately.
FAN
Thermostat begins call for fan. (G
terminal is energized).
Circulator fan is energized immediately at cooling speed.
Thermostat ends call for fan. (G
terminal is de-energized).
Circulator fan is de-energized immediately.
LIMIT
Limit switch string opens.
Oil primary control shuts off burner.
Circulator fan is energized immediately at heat speed.
EFT opens the 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 heating to cooling speed.
Limit switch string closes (with
existing call for heat).
EFT begins heat “fan off” delay sequence.
Circulating fan turns off after the selected heat “fan off” timing.
EFT re-closes the oil primary control T - T connections.
Oil primary control is energized, initiating burner light off.
Limit switch string closes (with
-
out existing call for heat).
Circulator fan turns off when heat “fan off” delay time is complete.
Normal operation resumes; EFT control is in standby mode awaiting next thermostat com
-
mand.
FAN
Continuous circulating fan is con
-
nected.
Circulating fan is energized when there is no call for heat, cool, or fan.
If fan operation is required by a call for heat, cool, or fan, the EFT switches off the continuous
fan speed tap before energizing the other fan speed.
EAC
Electronic Air Cleaner is con
-
nected.
Electronic air cleaner (EAC) connections are energized when the heat or cool speed of the cir
-
culator fan is energized. EAC connections are not energized when the optional continuous fan
terminal is energized.
HUM
Humidity control is connected.
Humidifier connections are energized when the oil burner motor is energized.
1168-1
Electronic Fan Timer Board (EFT)
Detailed Sequence Of Operation (BMLV)
Thermostat Input LEDs (LED1-5, LED8)
Six green LEDs are placed behind their respective thermostat connections (Y1, Y/Y2, G, DH, O, and W) and operate whenever a call is
present.
Thermostat calls for heat “W”
. The 24VAC input signal is passed to pin 2 of P1 and will drive the K1 relay that provides dedicated
contacts to the T-T input of the Oil Primary Control.
Thermostat calls for cool “Y1”
. The 24VAC input signal is passed to pin 6 of P1.
Thermostat calls for fan “G”
. The 24VAC input signal is passed to pin 15 of P1.
Thermostat calls for dehumidification “DH”
.
The 24VAC input signal is passed to pin 10 of P1.
Thermostat calls for reversing valve “O”
. The 24VAC input signal is passed to
pin 9 of P1.
APPENDIX C - SEQUENCE OF OPERATION AND TROUBLESHOOTING
