Table C-1: Electronic Fan Timer Board (Eft) Detailed Sequence Of Operation - ECR International WML-C Operation And Maintenance Manual

Table C-1: ELECTRONIC FAN TIMER BOARD (EFT) DETAILED SEQUENCE OF OPERATION

Mode Action
Thermostat calls for heat. ("W"
terminal is energized).
Thermostat ends call for heat.
("W" terminal is de-energized).
HEAT
Burner fails to light.
Established flame fails.
Thermostat begins
cool. (G and Y terminals are
energized).
COOL
Thermostat ends call for cool.
(G and Y terminals are de-
energized).
Thermostat begins call for fan.
(G terminal is energized).
FAN
Thermostat ends call for fan.
(G terminal is de-energized).
Limit switch string opens.
LIMIT
Limit switch string closes
(with existing call for heat).
Limit switch string
(without existing call for heat).
Continuous circulating fan is
FAN
connected.
Electronic Air
EAC
connected.
HUM Humidity control is connected.
a. EFT 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, the circulator fan is energized at heat speed.
a. R7184 oil primary control is de-energized, terminating the burner cycle.
b. Heat "fan off" delay timing begins. Length of delay depends on EFT dipswitch
settings. When timing is complete, the circulator fan is de-energized.
c. EFT returns to standby mode, (Oil primary control and circulator fan are off, unless
continuous fan operation is selected at the thermostat).
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.
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.
call for
a. Cooling contactor is energized immediately.
b. Circulator fan is energized at cool speed.
a. Cooling contactor is de-energized immediately.
b. Circulator fan turns off immediately.
a. Circulator fan is energized immediately at cooling speed.
a. Circulator fan is de-energized immediately.
a. Oil primary control shuts off burner.
b. Circulator fan is energized immediately at heat speed.
c. EFT opens oil primary control T - T connections. Circulating fan runs as long as
limit string stays open.
d.
If there is a call for cooling or fan, the circulating fan switches from heating to
cooling speed.
a. EFT begins heat "fan off" delay sequence.
b. Circulating fan turns off after the selected heat "fan off" timing.
c. EFT re-closes oil primary control T - T connections.
d. Oil primary control is energized, initiating burner light off.
a. Circulator fan turns off when heat "fan off" delay time is complete.
closes
b. Normal operation resumes; EFT control is in standby mode awaiting next
thermostat command.
a. Circulating fan is energized 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 EFT 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
Cleaner is
speed of the circulator fan is energized. EAC connections are not energized when
the optional continuous fan terminal is energized.
•
Humidifier connections are energized when the oil burner motor is energized.
System Response
25
30318 R4 9/9/2005