RBI LCD Series Installation & Operation Manual page 25

OPERATION SEQUENCE, ON/OFF
L225 through L2300
Note: Refer to the wiring diagram included with the
unit for further control system info.
POWER ON:
Demand for Heat:
1. The operator switch closes, energizing pump delay
timer TD4 and the water pump(s).
2. Water flow through the unit closes the water flow
switch contacts energizing blower delay timer TD3.
3. The system checks all primary limit(s) and other
interlocks before starting pre-purge. The unit will not
start if any switch is open.
Prepurge:
1. Blower delay timer TD3 energizes the high speed
windings of the blower(s).
2. Air pressure in the combustion chamber is sensed.
If the air pressure is sufficient, the pressure switch
closes allowing the blower delay timer TD1 to start
a 7 second pre-purge.
Ignition Trial:
1. Blower delay timer TD1 times out and the flame
sense module, FSM, is energized.
2. The FSM starts the 10-second ignition trial,
energizing relay R7, the pilot solenoid valve and the
spark generator.
3. The pilot valve and spark generator are energized
for the 10-second ignition trial. When the pilot flame
is sensed, the FSM sends 24VAC to its MV terminal
energizing the safety and main solenoid valves and
relay R8, de-energizing relay R7 and the spark
generator.
4. If the pilot flame isn't sensed, the FSM de-energizes
the PV terminal and waits 5 minutes before initiating
the second ignition trial. The blower(s), pump(s) and
optional power venter will remain on during this time.
5. On CSD-1 equipped units the blower(s) and optional
power venter will shut down and the boiler/water
heater will lock if the second ignition trial fails. The
unit must then be manually reset by depressing the
reset button on the left jacket panel.
6. On non-CSD-1 equipped units the FSM will wait 10
minutes after the second unsuccessful ignition
attempt then begin the ignition process described
in step 3 above. The FSM will continue to cycle the
unit through steps 3, 4 and 6 until the unit lights or
the demand for heat is removed.
Main Burner
Once the pilot is proven, the MV terminal on the FSM
is energized sending 24VAC to the safety and main
solenoid valves.
LCD INSTALLATION AND OPERATION INSTRUCTIONS
Normal Operation
On single stage units the blowers and gas valves
operate at one input.
Demand Satisfied:
1. When the demand for heat is satisfied the operator
switch will open, de-energizing relay R8, TD1, TD3,
TD4 the FSM and the pilot, main and safety
solenoid valves. The pilot and main flames are
extinguished.
2. The blower delay timer TD3 starts the 80 second
post-purge timing. The blower(s) shut(s) off when
TD3 times out.
3. The pump delay timer TD4 starts the post-purge
timing. The pump(s) remain on for 0.1 to 10 minutes
then shut(s) off when TD4 times out.
High Limit, Low Water Flow, Low Gas Pressure, High
Gas Pressure, Power Venter Interlock Faults
1. Electrical power to the gas valves, blower(s) and
optional power venter will be interrupted if any safety
is tripped.
2. The manual reset high limit can be reset by
depressing the rubber plug in the front top jacket
panel.
Low Air (Blocked Flue/Air Inlet)
• The pressure switch will monitor blower airflow.
• Air monitoring will begin at pre-purge. If a low air
condition is present power will not be supplied to the
FSM. The blower(s) will remain on.
OPERATION SEQUENCE, 2 STAGE
OPTION L400 through L2300
Note: Refer to the wiring diagram included with the
unit for further control system info.
POWER ON:
Demand for Heat:
1. The operator switch closes, energizing pump delay
timer TD4 and the water pump(s).
2. Water flow through the unit closes the water flow
switch contacts energizing blower delay timer TD3.
3. The system checks all primary limit(s) and other
inter-locks before starting pre-purge. The unit will not
start if any switch is open.
Prepurge:
1. Blower delay timer TD3 energizes the low speed
windings of the blower(s).
2. Once sufficient air pressure in the combustion
chamber is sensed the pressure switch closes
allowing the blower delay timer TD1 to start a 7
second pre-purge.
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