Instruction manual

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Table 18 Low air condition action, L225-L2300
Stage Control Action
1 No Power to Flame Sense Module
Table 19 Low air condition action, L600-L2300
Stage Control Action
1 No Power to Flame Sense Module
2 No Power to Flame Sense Module
OPERATION SEQUENCE, ON/OFF
L225 THROUGH L2300
Refer to the wiring diagram included with the unit
for further control system info.
POWER ON:
Demand for Heat:
1.  e 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 interlocks before
starting pre-purge.  e 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 su cient, 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 main solenoid valves and relay R8, de-energizing relay 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 MV terminal on the FSM is energized
sending 24VAC to the safety and main solenoid valves.
Normal Operation
On single stage units the blowers and gas valves operate at one
input.
Demand Satis ed:
1. When the demand for heat is satis ed the operator switch will
open, de-energizing relay R8, TD1, TD3, TD4, 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 optional 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 switch 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.