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

Mode

 

 

Action

 

 

 

 

System Response

 

 

 

 

 

 

 

a. EFT closes oil primary control T - T connections).

 

Thermostat calls for heat. ("W"

b. Ignition system and R7184 oil primary control start the furnace. Oil flows as long as

 

 

the oil primary control senses flame.

 

terminal is energized).

 

 

 

 

 

 

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.

 

Thermostat ends call for heat.

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.

 

("W" terminal is de-energized).

 

HEAT

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).

 

Burner fails to light.

 

 

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.

 

Thermostat

begins

call

for

a. Cooling contactor is energized immediately.

 

cool. (G and Y terminals are

 

b. Circulator fan is energized at cool speed.

COOL

energized).

 

 

 

 

 

 

 

 

 

 

 

Thermostat ends call for cool.

a. Cooling contactor is de-energized immediately.

 

 

(G and Y

terminals

are

de-

 

b.

Circulator fan turns off immediately.

 

energized).

 

 

 

 

 

 

 

 

 

 

 

 

 

Thermostat begins call for fan.

a. Circulator fan is energized immediately at cooling speed.

 

(G terminal is energized).

 

FAN

 

 

 

 

Thermostat

ends call

for fan.

a. Circulator fan is de-energized immediately.

 

 

(G terminal is de-energized).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

a. Oil primary control shuts off burner.

 

 

 

 

 

 

 

b. Circulator fan is energized immediately at heat speed.

 

Limit switch string opens.

 

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.

LIMIT

Limit

switch

string

closes

a. EFT begins heat “fan off” delay sequence.

 

b. Circulating fan turns off after the selected heat “fan off” timing.

 

(with existing call for heat).

c. EFT re-closes oil primary control T - T connections.

 

 

 

 

 

 

 

d. Oil primary control is energized, initiating burner light off.

 

 

 

 

 

 

 

 

 

 

 

Limit

switch

string

closes

a.

 

Circulator fan turns off when heat “fan off” delay time is complete.

 

b.

 

Normal operation resumes; EFT control is in standby mode awaiting next

 

(without existing call for heat).

 

 

 

thermostat command.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FAN

Continuous

circulating fan

is

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

connected.

 

 

 

 

 

 

 

 

 

 

continuous fan speed tap before energizing the other fan speed.

 

 

 

 

 

 

 

 

EAC

Electronic

Air

Cleaner

is

 

Electronic air cleaner (EAC) connections are energized when the heat or cool

 

speed of the circulator fan is energized. EAC connections are not energized when

connected.

 

 

 

 

 

 

 

 

 

 

 

the optional continuous fan terminal is energized.

 

 

 

 

 

 

 

 

HUM

Humidity control is connected.

 

Humidifier connections are energized when the oil burner motor is energized.

 

 

 

 

 

 

 

 

 

 

25

30318 R4 9/9/2005

Page 25
Image 25
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