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3.
Water level reaches LLCO (low water level cut-
off) probe for the water level control and to the
auxiliary LLCO probe for the auxiliary low level
cut-off control.
A.
Power to terminal 9 on the water level
control.
1)
LLCO relay energizes, LLCO-2 (N.O.)
contacts close and LED lights.
B.
Power to terminal LLCO on the auxiliary
low water level cut-off control.
1)
LLCO relay energizes, LLCO-2 (N.O.)
contacts close and LED lights.
NOTE: LLCO relays will remain energized
and LLCO LED'S will remain lit until the
water level drops below the LLCO probes
or the power switch is turned OFF.
4.
Water reaches LL (low level) probe.
A.
Power to terminal 2 on the water level
control is present but no switching occurs.
5.
Water reaches HL (high level) probe.
A.
Power to terminal 6 on water level control.
1)
The inverse latching relay of the
board is energized, changing the
state of ILR-1 (N.O.) and ILR-2 (N.C.)
contacts. The inverse latching relay
will remain energized through the
alternate latching path of ILR-1
contacts until the water level recedes
below the low level probe.
2)
With ILR-2 contacts open, HL relay is
de-energized, HL-3 (N.O.) contacts
open and HL LED goes out.
3)
Water fill solenoid is de-energized.
(boiler fill time approx. 11 min.)
6.
Manual re-set switch is pressed, energizing the
coils on the high limit and low water relays.
A.
Contacts 1 & 9 on the high pressure relay
change state and lock from N.C. to N.O.
and turn off the high pressure indicator
light. Concurrently, Contacts 1 & 9 on the
low water relay change state and lock from
N.C. to N.O. and turn off the low water
indicator light.
B.
Contacts 5 & 9 on the high pressure relay
change state and lock from N.O. to N.C.,
supplying power (NEUTRAL) to one side
of the auxiliary gas solenoid valve.
Concurrently, Contacts 5 & 9 on the low
water relay change state and lock from
N.O. to N.C., supplying power (L1) to the
other side of the auxiliary gas solenoid
valve.
NOTE: For both relays to energize, the high
pressure switch must be closed and the water level
in the boiler must be above the low level cut-off
probes in order for LLCO-2 (N.O.) contacts to close.
VL SERIES STEAMER - ELECTRICAL OPERATION
Page 43 of 88
C.
Auxiliary gas solenoid valve is energized
and opens to allow gas flow.
D.
As long as the ignition control module is
sensing a pilot flame, the internal main
valve (MV) contacts close (N.O.) on the
ignition control module. The main gas
valve is energized and gas begins flowing.
E.
Burners light and water in boiler begins to
heat up.
7.
Boiler steam pressure reaches upper limit set
point of 11 PSI. (Approximately 15 min.)
A.
Cycling pressure switch opens, main gas
solenoid valve de-energizes, gas flow
shuts off and burners go out.
B.
As boiler heats up and builds pressure,
some by-pass water/steam is produced
which runs into the steam drain box. This
causes the cold water condenser (CWC)
solenoid to cycle, cooling the drain water.
This solenoid is powered by the CWC
thermostat.
NOTE: Steam should not be seen entering a
compartment until the manual steam control arm is
pulled forward and locked.
8.
Boiler steam pressure drops below lower limit
set point of 9 PSI and the cycling pressure
switch closes.
A.
Boiler steam pressure is maintained by the
cycling of the pressure switch between the
upper and lower set point limits. The
cycling pressure switch continues to
energize and de-energize the main gas
solenoid valve starting and stopping the
flow of gas, which in turn, cycles the
burners on and off. This sequence
continues until one of the following occurs:
1)
Boiler pressurizes to 15 PSI, causing
the high limit pressure switch to open.
At that time, the auxiliary gas valve
de-energizes, shutting off the gas
flow to the burners and the high limit
failure light will come on. This light
will stay lit until the pressure drops
below the lower limit set point of 6
PSI and the manual re-set switch is
pressed.
2)
Boiler water level drops below the
LLCO probes for the water level and
the auxiliary low level cut-off controls
which then de-energizes the LLCO
relays, changing the contact state of
LLCO-2 (N.O.) back to open. This de-
energizes the main and auxiliary gas
solenoid valves. The gas solenoid
valves will remain off and the low
water level light will come on and stay
lit until the water level rises above the
LLCO probes and the manual re-set
switch is pressed.
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