VHX SERIES STEAMER - ELECTRICAL OPERATION
F24700 (October 2001) Page 46 of 68
SEQUENCE OF OPERATION
NEW STYLE CONTROLS - BOILER
This sequence of operation is written f or boi ler
bases with the new style boiler controls. See
"BOILER CONTROL STYLES" under "GE NE RA L" .
Refer to schematic diagram T SP1480.
Initial Fill and Preheat
Conditions.
A. Power switch OFF.
B. Boiler connected to correct v oltage
(120VAC).
C. Boil er pr oper l y grounded.
D. Gas and water supply v alve(s) ON.
E. Main gas valve manual valve in ON
position
F. Cycling pressure switch closed.
G. High limi t pressure switch closed.
H. Cold water condenser (CW C) thermostat
open.
I. Automati c blowdown solenoid valve
(A.B.D.) open and boiler empty.
2. Turn power switch ON.
A. Automatic Blowdown valve (N.O.) is
energized and close.
B. Water level c ont rol (WLC) energized.
1) High level (HL) r el ay energized, HL-3
contacts (N.O.) close.
a. Fill solenoid energized, water
begins filling the boiler (fill time
4-11 min.).
2) HL LED lit.
C. Auxiliary water level control is powered.
1) Aux. LLCO N.O. contacts remain
open.
D. 120VAC to one side of K5(1) N.O., K1(1)
N.O., K3(1) N.O., K4(1) N.O. contacts.
E. N6 lit. Low Wat er light (control panel) li t
thru K3(1) N.C.
F. N8 lit. Hi Pressure light (control panel) lit
thru K4(1) N.C.
G. N1 lit. 24VAC transformer is energized
and relay board is powered.
1) 24VAC to one side of auxiliary water
level control LLCO contacts (N.O.).
2) N3 lit. K2 energized through the high
limit pressure switch contacts (N.C.).
a. K2 contacts K2(1) N.O. & K2(2)
N.O. close, no power
transferred.
3) N9 lit. 24VAC to one side of K3(2)
N.O. contacts through cycling
pressure switch N.C.
3. Water l evel reaches LLCO probe for both water
level control and auxiliary low level control.
A. LLCO relay on water level board
energizes, LLCO contacts (N.O.) close
1) LED on board lights.
B. Aux. LLCO relay energizes, aux. LLCO
contacts (N.O.) close.
1) LED on board lights.
2) N2 lit. K1 is energized.
a. K1(1) N.O. close.
b. N4 lit. Ready light (green) on the
control panel manual reset
switch, ON.
3) K1(2) N.O. close.
NOTE: No power is transferred until m anual
reset switch p r essed.
NOTE: The LLCO and aux. LLCO rel ay s wil l
remain energized and LLCO LED’S will remain
lit until the water lev el drops below the LLCO
probes or the power switch is turned OFF.
NOTE: The reset switch could be pressed to
start combustion blower & ignition cycle but it’s
preferred to let the boiler fill the to the "High
Level" before continui ng.
4. Water r eac hes LL (l ow level) probe.
5. Water r eac hes HL (hi gh level) probe.
A. Fill solenoid is de-energized.
B. HL-LED
6. Manual reset switch pressed.
A. N5 lit. K3 is energized (120VAC).
NOTE: Relay K3 remains energiz ed t hrough
K3(1) N.O. locking circuit.
1) N6 goes out. K3(1) N.O. contacts
close and K3(1) N.C. contacts open.
2) Low water light (control panel) goes
out.
3) N10 lit. K3(2) N.O. contacts close.
a. 24VAC to one side of K 4( 2) N. O.
contacts.
B. N7 lit. K4 is energized (120VAC).