10.Duringthepost-purgecycle,thefan-limitcontrolBI-
metalcoolsdownto the factoryset pointof 90
degreesFahrenheit,andthecirculatingairblower
turnsoff.
I NOTE: With burner relay contact open, the Riello 40-
BF will post-purge when 115 volt power is applied to the
burner.
2.3) Sequence of operation - Beckett
AFG and Riello 40-F, chimney:
1. For the AFG burner, the T-T terminal have to be
jumped on the primary control of the burner.
2. Normally open contact (W-R) on SPDT relay closed
when thermostat calls for heat.
.
AFG Burner: The motor starts and spark is
established. The pump pressure builds and the
poppet valve opens admitting fuel to the nozzle.
Pressure builds and poppet valve opens, allowing
oil to flow through nozzle.
40F: Burner motor starts. The burner motor fan
pre-purges the combustion chamber and vent for
10 seconds, establishing the combustion air
pattern. During this time the solenoid valve holding
coil pressure will be approximately 100 psig.
Solenoid valve opens, allowing oil to flow through
nozzle. At the same time, the burner motor's
ignition coil produces spark.
4. Spark ignites oil droplets.
5. Cad cell senses flame and burner continues to fire.
Ignition transformer ceases sparking (Riello R40-F).
6. After fan-limit control heats up to the factory set
point, the circulating air blower starts.
.
The circulating air blower and burner motor remain
on until the thermostat is satisfied (AFG). The
ignition transformer continues to spark (AFG). The
solenoid valve remains open (R40-F).
8. Thermostat is satisfied.
9. SPDT relay contacts open, solenoid valve closes
(R40-F), burner fan motor shuts down. The ignition
transformer ceases sparking (AFG).
10. The fan-limit control Bl-metal cools down to the
factory set point of 90 degrees Fahrenheit, and the
circulating air blower turns off.
2O
2.4) Sequence of operation - internal
furnace controls (All models) :
No call for heating or cooling:
Power is available to the Electronic Air Cleaner (EAC)
at all times. Power at L1 enters the common terminal of
the single pole double throw (SPDT) relay, and then
passes through the normally closed (NC) switch of the
relay and continues to the normally closed (NC) switch
of the fan control. This provides power to the constant
blower operation speed tap on the blower motor if the
constant (low speed) blower operation switch is
selected to be close. The low speed motor tap would
normally be chosen for constant blower operation.
Call for heat:
Power comes from L1 to the limit control and then
leaves the limit control via the red wire to provide power
to the burner. RH W close in the thermostat
completing a 24 volt circuit the SPDT relay coil. This
relay energises and switches 115 volts power to
operate the oil burner.
When the plenum temperature reaches the fan "On"
setting, the normally open (NO) fan control contacts
close and the normally closed (NC) contacts open.
Power then flows to the heating speed tap selected on
the blower motor, and to the HUM power lead to supply
115 volts to the humidifier transformer.
Call for cooling:
Rc - G close in the thermostat completing a 24-volt
circuit to the SPDT relay coil. The NC contacts open
interrupting power to the fan control. The NO contacts
close and power flows to the cooling speed tap
selected.
Rc - Y also close in the thermostat completing a 24-volt
circuit to the outdoor condensing unit contactor coil. The
contactor closes and switches power to the compressor
and condenser fan in the condensing unit.
2.5) Sequence of operation - DV-2000 TM
Venting system:
Normal operation:
1. Before a call for heat the contacts of the pressure
switch are closed.
. When the room thermostat calls for heat the
normally open contact W-R close and the burner
blower starts and creates suction in the intake
piping circuit and a pressure in the vent piping
circuit.
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