Instruction manual

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OPERATION SEQUENCE, 2 STAGE OPTION
L600 THROUGH L2300
Refer to the wiring diagram included with the unit
for further control system info.
POWER ON:
Demand for Heat:
1.  e low operator switch closes, energizing pump delay timer
TD4 and the water pump(s).
2. Water  ow through the unit closes the water  ow switch contacts
energizing blower delay timer TD3.
3.  e system checks all primary limit(s) and other inter-locks
before starting pre-purge.  e 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 su cient air pressure in the combustion chamber is sensed
the pressure switch closes allowing the blower delay timer TD1
to start a 10 second pre-purge.
Ignition Trial:
1. Blower delay timer TD1 times out and the  ame sense module,
FSM, is energized.
2.  e FSM starts the 10-second ignition trial, energizing relay
R7, the pilot solenoid valve and the spark generator.
3.  e pilot valve and spark generator are energized for the
10-second ignition trial. When the pilot  ame is sensed, the
FSM sends 24VAC to its MV terminal energizing the safety
and low  re-side of the main solenoid valves and relay R8,
de-energizing R7 and the spark generator.
4.
If the pilot  ame isn’t sensed, the FSM de-energizes the PV
terminal and waits 5 minutes before initiating the second ignition
trial.  e 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.  e unit must then be manually
reset by depressing the reset bu on on the le jacket panel.
6. On non-CSD-1 equipped units the FSM will wait 10 minutes
a er the second unsuccessful ignition a empt then begin the
ignition process described in step 3 above.  e 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 FSM sends 24VAC to its MV terminal
energizing the safety and low- re side of the main solenoid valves.
Normal Operation
• Staging is controlled by the return water aquastat. Relays R2
and R2R are energized by the return water aquastat when more
heat input is required.  e hi-speed windings of the blower(s)
are energized.
• Relay R9 is energized when the hi- re pressure switch senses
adequate air pressure to sustain hi- re combustion. R9 energizes
the hi- re side of the main solenoid valve.
• Stage 1 will operate  rst and last.
For a change from stage 1 to 2, a 30 second time delay
is provided in the pressure switch switching circuit.
 e time delay TD6 provides a hold state that allows
the blower to reach full speed and close the high  re
pressure switch before it is energized to con rm proper
air  ow.
Demand Satis ed:
1. When the demand for heat is satis ed the low operator switch
will open, de-energizing relays R2, R2R, R8, R9, TD1, TD3,
TD4, TD6, the FSM, and the pilot, main and safety solenoid
valves.  e pilot and main  ames are extinguished.
2.  e blower delay timer TD3 starts the 80 second post-purge
timing.  e blower(s) shut(s) o when TD3 times out.
3.  e pump delay timer TD4 starts the post-purge timing.  e
pump(s) remain on for 0.1 to 10 minutes then shut(s) o 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 power venter
will be interrupted if any safety is tripped.
2.  e manual reset high limit can be reset by depressing the reset
bu on on the le jacket panel.
Low Air (Blocked Flue/Air Inlet)
•  e pressure switches will monitor blower air ow.
• Air monitoring will begin at pre-purge. If a low air condition is
present, power will not be supplied to the FSM.  e blower(s)
will remain on.