SERVICE MANUAL
VHX BOILER BASE SERIES
HIGH EFFICIENCY
ELECTRIC STEAMER
VHX24E
VHX24E5 ML-126853
MHB24E ML-126857 (BASE ONLY)
ML-126852
VHX24E SHOWN
- NOTICE -
This Manual is prepared for the use of trained Vulcan Service
Techniciansandshouldnotbeusedbythosenotproperlyqualified.
If you have attended a Vulcan Service School for this product, you
may be qualified to perform all the procedures described in this
manual.
This manual is not intended to be all encompassing. If you have not
attended a Vulcan Service School for this product, you should read,
in its entirety, the repair procedure you wish to perform to
determine if you have the necessary tools, instruments and skills
requiredtoperform theprocedure. Proceduresforwhichyoudonot
have the necessary tools, instruments and skills should be
performed by a trained Vulcan Service Technician.
Reproduction or other use of this Manual, without the express
written consent of Vulcan, is prohibited.
For additional information on Vulcan-Hart or to locate an authorized parts and
A product of VULCAN-HART
LOUISVILLE, KY 40201-0696
F25154 (February 2004)
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VHX SERIES STEAMERS
ELECTRICAL OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Component Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Cabinet Base Boiler Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Cooking Compartment Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Component Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Boiler Base Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Cooking Compartment Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Water Level Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Low Level Cut-Off & Differential Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Auxiliary Low Level Cut-Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Relay Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Layout, Legend & Diagnostic Test Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Sequence of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Cooking Compartment Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Boiler Base Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Cooking Compartment Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Boiler Base Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Heating Element Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Cooking Compartment Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
CONDENSED SPARE PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
© VULCAN 2004
Page 3 of 48
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VHX SERIES STEAMERS - GENERAL
GENERAL
Cooking Compartments Control Panel
INSTALLATION, OPERATION
AND CLEANING
Refer to the Installation and Operation Manual for
specific instructions.
INTRODUCTION
Steam Cooking
Convection cooking in pressure-less steaming
compartments will steam cook fresh foods or will
steam defrost and cook frozen foods providing the
maximum color, flavor and nutritional value with the
least expenditure of energy and labor. The pressure-
less steaming compartments on the VHX series,
allows the operator to open and close the door
anytime during a cooking cycle. The steam supply
will shut off when the door is opened, then re-start
when the door is closed.
Model Designations
Boiler Control Panel
Compartment Pan Capacity
PAN
DEPTH
(INCHES)
NUMBER OF PANS
PER COMPARTMENT
MODEL
2
4.0
2.5
1.0
4.0
2.5
1.0
VHX24E
3
6
3
VHX24E5
5
10
Pan Size 12" x 20"
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VHX SERIES STEAMERS - GENERAL
The desired water properties can best be achieved
Boiler Code Descriptions
by using a properly maintained water treatment
system.
Vulcan-Hart incorporates redundant controls in
compliance with the CSD-1 controls and safety
devices for boiler construction on the high efficiency
steamer models. A description of the code is listed
below.
The water level probes in the boiler use ions in the
water to detect the water level. Do not use fully
demineralized or de-ionized water since it is non
conductive and the water level can not be
detected.
CSD-1 Construction - Redundant controls in the
electrical safety circuits that, if tripped, must
manually be reset after the condition causing the trip
subsides. The controls provide low water level cut-off
protection (LLCO), auxiliary low water level cut-off
protection (Aux LLCO), and high pressure protection
for the boiler. Additionally, the low water and high
pressure safety circuits have individual indicator
lights that will illuminate for a visual verification of the
shutdown mode.
The use of strainers will not remove minerals from
the water.
Water supplies vary from state to state and from
locations within a state. Therefore, a water
treatment specialist should be consulted before
the installation of any steam generating equipment.
Steamers that operate over a long period of time
without the benefit of a water treatment system,
which have developed a heavy scale build-up,
should be cleaned before using the system.
CSD-1 construction requires operator intervention in
the event of a shutdown. The indicator lights show
the operator which safety system was shutdown.
SPECIFICATIONS
WATER CONDITIONING
Boiler Pressure
Operating - 10 to 12 psi
Maximum - 15 psi
Water Supply
Furnishing the boiler with treated water to reduce
scale formation is advised. Scale formation will
reduce steam output, cause premature component
failure, and shorten equipment life. Most water
supplies contain scale producing minerals such as
calcium and magnesium. As steam is generated, the
minerals remain and dissolve into the water. As the
concentration of these minerals increases past a
certain point, they precipitate from the water and
coat the inside of the boiler, heating elements, and
water level sensors. Because of the high
The fact that a water supply is potable is no
guarantee that it is suitable for steam generation.
The supply connection to the steam generator
should be treated water and must be within the
guidelines listed below. For drain water cooling only,
an untreated water supply connection should be
used.
temperature of these surfaces, the precipitated
minerals bake onto them and become very difficult to
remove.
Supply connection
Supply pressure should be
Hardness*
cold water
20-60 psig
This may cause several problems:
1. Reduced heat transfer efficiency.
2. Premature heating element failures.
3. False readings from water level sensors.
less than 60 ppm
less than 13 ppm
less than 4 ppm
7 to 8
Silica
Total Chloride
PH Range
These problems are common to any steam
equipment manufacturer, regardless of design, but
can be minimized by furnishing the boiler with
treated water.
less than 5
microns
Un-dissolved Solids
Other factors affecting steam generation are iron
content, amount of chlorination and dissolved gases.
*17.1 ppm = 1 grain of hardness
Page 5 of 48
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VHX SERIES STEAMERS - COMPONENT FUNCTION
Electrical
MODELS
AMPERAGE
TOTAL
KW
1 PHASE
3 PHASE
208V 240V 208V 240V 480V
24
36
42
48
116
---
100
---
67
100
117
---
58
87
29
44
---
58
VHX24E,
VHX24E5,
MHB24E
---
---
---
---
---
116
1. Amperage values in the table are
nominal. Tolerance is +5/-10%.
NOTES:
2. Voltage values are @ 60HZ.
3. 24KW 3 phase is standard for both
models. If a 24KW single phase
connection is needed, the machine is
field convertible at the terminal block.
See heating element circuit diagram
AI1388.
TOOLS
Standard
!
!
Standard set of hand tools.
VOM with AC current tester.
NOTE: Any quality VOM with a sensitivity of at
least 20,000 ohms per volt can be used.
Special
!
The recommended deliming chemical for the
water treatment system in use, for deliming of
the boiler.
!
!
Heat Exchanger Gasket (joint sealant strip,
Teflon) P/N 854058-1.
Loctite 242 thread sealant or equivalent
P/N 520228. Used on the top and bottom
cooking compartment door screws.
!
3/8 x 16 tap. Used for cleaning out threads on
front boiler flange.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
REMOVAL AND REPLACEMENT OF PARTS
PRESSURE SWITCH CONTROL
BOX COMPONENTS
WARNING: DISCONNECT THE
ELECTRICAL POWER TO THE
MACHINE AND FOLLOW LOCKOUT /
TAGOUT PROCEDURES.
CAUTION: Certain components in this system are subject to damage by electrostatic discharge during
field repairs. A field service grounding kit is available to prevent damage. The field service grounding kit
must be used anytime a control board is handled.
1. Open the cabinet base door.
2. Remove cover from pressure switch control box.
3. Disconnect lead wires from component being replaced.
4. To remove:
A. Cycling pressure switch.
1) Disconnect compression fittings in the pressure supply line leading to the switch.
2) Remove mounting nuts from pressure switch mounting panel.
3) Disconnect conduit from box.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
MAIN CONTROL BOX
COMPONENTS
WARNING: DISCONNECT THE
ELECTRICAL POWER TO THE
MACHINE AND FOLLOW LOCKOUT /
TAGOUT PROCEDURES.
CAUTION: Certain components in this system
are subject to damage by electrostatic discharge
during field repairs. A field service grounding kit
is available to prevent damage. The field service
grounding kit must be used anytime a control
board is handled.
1. Open the cabinet base door.
2. Remove heating element cover then main
control box cover.
4) Disconnect lead wires from other
components as necessary then
remove pressure switch mounting
panel.
5) Remove screws securing switch to
panel.
B. High limit pressure switch.
1) Disconnect compression fittings from
switch then remove from box.
C. Boiler fill or cold water condenser valve.
1) Turn water supply off and disconnect
compression fittings from valve.
2) Remove valve bracket mounting
screws.
D. Main or auxiliary water level control board
1) Compress locking tab on the board
mounting standoffs and remove
control board.
3. Disconnect lead wires from component being
replaced.
5. Reverse procedure to install.
NOTE: Before installing the cycling pressure switch,
use pressure scale on the switch to preset the
approximate cut-out (off) and cut-in (on) set points.
A. Adjust the installed pressure switch
(cycling or high limit) as outlined in
SERVICE PROCEDURES AND
ADJUSTMENTS.
6. Check for proper operation.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
WATER LEVEL GAUGE
ASSEMBLY
WARNING: DISCONNECT THE
ELECTRICAL POWER TO THE
MACHINE AND FOLLOW LOCKOUT /
TAGOUT PROCEDURES.
1. Remove right side panel.
NOTE: If right side panel is not accessible, open the
cabinet door and remove control panel to access
from front.
2. Loosen packing nuts on glass tube until threads
disengage then slide nut toward center of tube.
4. To remove:
A. Contactors.
1) Release catch at the base of
contactor and remove from DIN rail.
B. Relays.
1) Remove from socket.
C. Relay Board.
1) Compress locking tab on the board
mounting standoffs and remove
control board.
5. Reverse procedure to install and check for
proper operation.
NOTE: When the main control box cover is properly
installed, the gap between the front lip of cover and
main control box must be maintained for adequate
ventilation. Do not seal the gap.
LEFT SIDE VIEW SHOWN
3. Slide glass tube up until it clears the bottom
fitting, tilt out at the bottom and slide glass tube
down to remove.
NOTE: Clean glass tube if cloudy or replace if chips
or cracks are noticed.
4. Remove packing nuts from glass tube.
A. A single rubber washer is installed inside
each packing nut. Clean debris from
washer and inspect the rubber for cracks
or hardening.
1) If rubber washer needs replacing,
install a replacement rubber washer in
each packing nut.
NOTE: When installing, ensure friction
washer (flat) is installed inside the packing
nut before rubber washer.
5. To Install:
A. Slide packing nuts onto glass tube and
position each nut approximately 1" from
open end on tube.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
B. Insert one end of glass tube into top gauge
fitting then align opposite end of tube with
bottom gauge fitting.
C. Lower the glass tube into bottom gauge
fitting then center the tube between top &
bottom gauge fittings.
D. Hold glass tube in place and hand tighten
the bottom packing nut then top.
E. Tighten each packing nut and additional
1/2 turn.
CAUTION: Do not over tighten packing nuts or
damage to glass tube may occur.
6. Re-connect power to the machine.
7. Turn power switch on and allow boiler to fill.
A. Press reset switch to begin heating (green
ready light on).
8. Check gauge glass for water and steam leaks.
A. If necessary, slowly tighten packing nuts
until leak stops.
4. Disconnect lead wires from heating element at
the contactor terminals.
9. Install right side panel or front control panel (if
removed).
5. Remove mounting nuts from heating element
and remove the element from boiler.
HEATING ELEMENTS
WARNING: DISCONNECT THE
ELECTRICAL POWER TO THE
MACHINE AND FOLLOW LOCKOUT /
TAGOUT PROCEDURES.
1. Turn power switch off and allow boiler to
blowdown/drain.
2. Open the cabinet base door.
3. Remove heating element cover then main
control box cover.
6. Clean the mating surface on mounting plate
then install a replacement gasket and heating
element.
7. Reverse procedure to install and check for
proper operation.
NOTE: When installing heating element, route the
lead wires between the contactors.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
6. Loosen both conduit locking nuts (1 1/2" & 3/8")
HEATING ELEMENT MOUNTING
in main control box.
PLATE
7. Loosen conduit nut (1 1/2") on elbow connected
to main control box.
WARNING: DISCONNECT THE
ELECTRICAL POWER TO THE
MACHINE AND FOLLOW LOCKOUT /
TAGOUT PROCEDURES.
8. Remove mounting bolts for main control box.
A. Lift main control box to remove from the
frame and position it to the left side.
9. Remove heating element mounting plate.
1. Remove heating elements as outlined under
HEATING ELEMENTS.
2. Loosen mounting hardware securing control
panel to frame and lower the panel.
10. To install:
A. Clean the mating surfaces on heating
element mounting plate and boiler.
B. Install new gasket on boiler side of
mounting flange.
3. On models with cooking compartments only,
disconnect power cord from power switch box
(rear of control panel).
4. Disconnect pressure gauge tube from fitting at
tee.
5. Disconnect lead wire from Aux LLCO probe.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
C. Position heating element mounting plate
with mounting studs for the element cover
at the top.
NOTE: When installing heating element
mounting plate, install and tighten the mounting
bolts as indicated to ensure the mounting plate
is flush with boiler flange and gasket is evenly
compressed. If bolt is not threading properly by
hand, clean out the threads with a 3/8 x 16 tap.
D. Align mounting holes then press and hold
heating element mounting plate against the
gasket. Install two bolts at the top and two
bolts at the bottom. Hand Tighten Only.
E. Starting with the bottom bolts, tighten each
bolt a few turns at a time and alternate
between the bottom and top bolts.
RIGHT SIDE VIEW SHOWN
8. Remove gauge glass as outlined under
WATER LEVEL GAUGE ASSEMBLY.
F. Install two bolts at the left and two bolts at
the right on the heating element mounting
plate. Tighten each bolt a few turns at a
time and alternate between the left and
right bolts.
9. Disconnect water level probe lead wires.
10. Remove coil from blowdown/drain valve.
11. Disconnect boiler fill and cold water condenser
valve water lines and remove lines.
G. Install the four remaining bolts. Tighten
each bolt a few turns at a time and
alternate between the four remaining bolts.
11. To complete heating element mounting plate
installation, reverse procedure from main
control box removal.
BOILER ASSEMBLY
WARNING: DISCONNECT THE
ELECTRICAL POWER TO THE
MACHINE AND FOLLOW LOCKOUT /
TAGOUT PROCEDURES.
NOTE: To perform this procedure, the steamer must
be accessible from all sides.
1. Turn power switch off and allow boiler to
blowdown/drain.
LEFT SIDE VIEW SHOWN
12. Remove cover from pressure switch control box
and loosen conduit locking nut.
2. Turn water supply off.
3. Remove left and right side panels.
13. Remove mounting screws for pressure switch
control box.
4. Raise steamer from the bottom right side by
approximately three inches to drain the
remaining water from boiler. Lower steamer
when boiler is empty.
14. Disconnect pressure relief valve drain line at
the valve.
15. Disconnect water level probe housing air
equalization tube and remove tube.
5. Remove heating element mounting plate as
outlined under HEATING ELEMENT
MOUNTING PLATE.
16. Disconnect water level probe housing drain line
from condenser drain box.
6. Disconnect pressure gauge tube from gauge.
7. Disconnect air equalization tube and remove.
17. Disconnect boiler drain line from condenser
drain box.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
LEFT SIDE VIEW SHOWN
18. Separate union at boiler drain.
LEFT SIDE VIEW SHOWN
19. On models with cooking compartments:
23. Remove main control box and pressure switch
control box from boiler base.
A. Remove the left and right access panels
between the cooking compartments and
boiler base.
24. Remove bolts securing boiler to base frame
then slide boiler forward to remove.
B. Disconnect flexible steam supply line from
boiler tee to cooking compartments and
remove the line.
25. Remove all plumbing components from boiler
and install on replacement boiler.
26. Install replacement boiler but hand tighten
mounting bolts only.
C. Disconnect both drain lines from cooking
compartments to condenser drain box and
remove the lines.
27. To complete boiler installation, reverse
procedure from main control box and pressure
switch control box removal.
20. On models with steam generator base only,
disconnect steam supply line from boiler tee.
28. When all connections to boiler are made,
tighten boiler mounting bolts to secure boiler to
base frame.
21. Loosen conduit nut on field connection box and
slide nut down onto conduit.
22. Remove cover from field terminal box and
disconnect lead wires from terminal block.
29. Check for proper operation.
DESCALER (Cathodic Protector)
NOTE: The descalers are accessible only through
the heating element mounting plate opening in boiler.
1. Remove heating element mounting plate as
outlined under HEATING ELEMENT
MOUNTING PLATE.
2. Remove the two descalers hanging from the
front horizontal support rod.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
5. Adjust the door as outlined in DOOR SEALING
ADJUSTMENT under COOKING
COMPARTMENT.
NOTE: Do not over tighten gasket plate screws as
this will compress the gasket excessively and
interfere with proper door sealing.
NOTE: Damage to the gasket sealing surface, such
as nicks or cuts, will cause steam leakage.
3. To install:
A. On the two replacement descalers, stretch
the coiled wire (cathode) at the top to
elongate the wire then form an open loop.
B. Hang the descalers on the front horizontal
support rod; one to the left of the heating
elements and one to the right.
C. Position the descalers so the core (anode)
is below the minimum water level in the
boiler and hanging freely.
NOTE: To function properly, the descalers must
not contact the interior surfaces of the boiler or
the heating elements.
Handle
1. Open the door.
COOKING COMPARTMENT
DOOR(S)
2. Remove screws from the top and bottom of the
door.
3. Pull the inner door panel out from the door
housing with the gasket plate and gasket still
attached.
Removal
1. Remove top cover.
2. Open the door.
3. Pull hinge rod up.
4. Reverse the procedure to install, making sure
the door bushings are in place.
Gasket
1. Open the door.
2. Remove screws from the gasket plate.
3. Pull the gasket plate out from the door housing
and remove the gasket.
4. Position the new gasket on the gasket plate and
reverse the procedure to install.
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VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS
3. Pull the inner door panel out from the door
housing with the gasket plate and gasket still
attached.
4. Remove the screws from the side edge of the
door that secure the latch mechanism and
remove the latch from the door.
4. Remove the nuts and spacers from the handle
screws and remove the handle from the door.
NOTE: When installing, the latch lever must rest on
top of the handle latch screw.
5. Reverse procedure to install.
NOTE: When installing the spacers, the smaller
diameter fits into the slot in the door and the latch
lever must rest on top of the handle latch screw.
NOTE: When installing screws at the top and bottom
of door, apply thread sealant.
5. Reverse procedure to install.
NOTE: When installing screws at the top and bottom
of door, apply thread sealant.
Latch Assembly
1. Open the door.
2. Remove screws from the top and bottom of the
door.
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
SERVICE PROCEDURES AND ADJUSTMENTS
WARNING: CERTAIN PROCEDURES IN THIS SECTION REQUIRES ELECTRICAL TEST OR
MEASUREMENTS WHILE POWER IS APPLIED TO THE MACHINE. EXERCISE EXTREME CAUTION AT ALL
TIMES. IF TEST POINTS ARE NOT EASILY ACCESSIBLE, DISCONNECT POWER AND FOLLOW LOCKOUT /
TAGOUT PROCEDURES, ATTACH TEST EQUIPMENT AND REAPPLY POWER TO TEST.
8. Install descalers (cathodic protectors).
BOILER
9. Install heating element mounting plate.
Inspection
10. Install heating elements.
The boiler should be inspected for excessive lime
scale build-up in a time frame dependant on the
11. Check for proper operation.
quality of the local water supply and steamer usage.
In hard water areas or for steamers heavily used, a
more frequent interval should be used. This
inspection consists of an internal examination and
cleaning of the boiler, an examination of the two
hanging descalers (cathodic protectors) and for lime
scale build-up on the water level probes. Also, check
all boiler controls, including the pressure switches.
Deliming
Refer to the water filtration system manual supplied
with steamer for specific instructions.
Descaler (Cathodic Protector)
Two descalers are installed inside the boiler and are
used as a preventative measure to:
•
•
•
Reduce scale deposit build-up
Periodic service must be performed as outlined in
the BOILER procedures. See WATER
CONDITIONING under GENERAL.
Help remove existing scale deposits
Inhibit boiler and component corrosion
Clean-Out
The descaler has a coiled wire (cathode) wrapped
around a solid cylindrical core (anode) that hangs by
an open loop from the front horizontal support rod
inside the boiler.
1. Turn power switch off and allow boiler to
blowdown/drain.
2. Remove heating element mounting plate as
outlined in REMOVAL AND REPLACEMENT
OF PARTS.
The descaler materials serve as a sacrificial anode
and cathode combination that chemically react with
the contents of the boiler to meet the three objectives
outlined above.
3. Inspect descalers (cathodic protectors) as
outlined under DESCALER (CATHODIC
PROTECTOR) in this section.
4. Remove both descalers from boiler.
5. Clean interior of boiler using a wire brush or
equivalent.
A. Dislodge and remove all loose scale from
boiler. All loose debris must be removed
from the boiler.
B. Remove all loose scale form the heating
element mounting plate.
C. Clean the mating surfaces of the heating
element mounting plate and boiler.
6. Check boiler drain and drain line plumbing for
obstructions.
A. Remove cap and strainer screen from
strainer body. Separate screen from cap
and clean debris from screen.
B. Through the front opening in boiler, flush
out the boiler and drain line plumbing with
clean water.
7. Check probe housing and water level probes for
scale build-up and clean as necessary.
F25154 (February 2004)
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
1. Access the descalers (cathodic protectors) as
WATER LEVEL CONTROLS
TEST
outlined in REMOVAL AND REPLACEMENT
OF PARTS.
2. Inspect the two descalers hanging in boiler.
A build-up of lime scale on or near the water level
sensing probes may cause them to retain moisture
on the probe surface and can give a false reading.
Also, a cracked or damaged insulator may give a
false reading.
NOTE: As descalers erode over time, the diameter
decreases while the length increases.
NOTE: A new descaler is approximately 1 3/8"
diameter and 3 3/4" long at the core.
These conditions may cause one or more of the
following to occur:
A. If either descaler has increased to
approximately 6" in length and the core is
breaking apart (pieces falling off), both
descalers should be replaced; or on an
annual basis.
•
•
•
•
Boiler no heat
Boiler no fill
Boiler overfill
WATER LEVEL PROBE
HOUSING BLOWDOWN
Boiler no fill and dry fire
NOTE: Dry firing may cause damage to heating
elements or boiler. If this condition is suspected, the
affected components should be inspected.
The water level probe housing fills to the same water
level in the boiler; and equalizes to the operating
pressure in the boiler. When the manual ball valve
on the probe housing assembly is opened, water and
steam are blown thru this valve and should be visible
exiting steamer drain. The probe housing blowdown
should be performed in a time frame dependant on
the quality of the local water supply and steamer
usage. In hard water areas or for steamers heavily
used, a more frequent interval should be used. The
blowdown procedure is essential to proper operation
and component life by removing sediment and
scalants that may be lodged in the probe housing.
Main Water Level Control
NOTE: The main water level control is a dual
functioning control that provides low level cut-off
protection and differential water level control
1. Turn power switch on and verify:
A. Low water light is lit (front control panel).
B. HL LED is lit on the water level control
board.
C. Boiler is filling with water.
1. Turn power switch on and allow boiler to
completely fill (approximately 1" of water visible
in sight glass).
D. If boiler isn’t filling with water:
1) Verify 120VAC to boiler fill valve.
2. Press reset switch to begin heating and allow
boiler to reach operating pressure.
2) Verify water supply is on and boiler fill
valve isn’t clogged.
3. Remove left side boiler base panel to access
the manual ball valve.
2. At the end of the initial fill:
A. Verify approximately 1" of water visible in
sight glass.
WARNING: THE STEAMER AND ITS PARTS ARE
HOT. USE CARE WHEN OPERATING, CLEANING
OR SERVICING THE STEAMER. THE BOILER
CONTAINS LIVE STEAM. STAY CLEAR WHEN
OPENING THE VALVE.
B. Verify green ready light is lit (front control
panel).
C. Verify HL LED is not lit and LLCO LED is lit
on the water level control board.
4. Open the ball valve for approximately one
minute while under pressure to thoroughly flush
the probes and housing.
3. Open the ball valve on probe housing assembly
(boiler left side) about half way. This will allow
boiler water to drain slowly and activate a fill
cycle. Do not press the reset switch to start
heating. The next step requires a visual sight
glass measurement that cannot be obtained if
there is boiling action in the vessel.
5. Close the ball valve and replace left side panel.
6. Press reset switch to resume heating and allow
boiler to reach operating pressure.
7. Steamer is ready for use.
A. Verify water level in sight glass drops 1/4"
to 3/8" before a fill cycle is initiated. Repeat
at least twice to verify correct fill.
B. If proper fill wasn’t obtained:
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
1) Verify wire color connections are
correct at probe numbers 50, 51 & 52,
and at the water level control board.
A. Turn power switch on and allow boiler to
fill. Do not press the reset switch to start
heating.
2) Turn power switch off.
B. Turn water supply off and open the ball
valve on probe housing assembly. This will
allow boiler water to drain.
3) Remove probe assembly, clean lime
scale build-up from the probes and
compare probe lengths to drawing.
C. When water level is no longer visible in
sight glass and is below LLCO probe;
LLCO LED should turn off, LLCO relay
should de-energize and return LLCO relay
contacts to there shelf state.
D. Repeat at least twice to verify correct
LLCO operation.
Auxiliary Low level Cut-Off Control
5. Turn power switch off.
6. Disconnect lead wire from Aux LLCO probe.
4) Disconnect 3/8” flexible line (air
equalization tube) from probe housing
assembly and from boiler tee. Check
flex line for obstructions and remove
as necessary.
5) Disconnect 3/8” flexible line (pressure
switch tube) from boiler tee. Remove
boiler tee and check for obstructions
in the tee and in the mounting hole.
Remove obstructions as necessary.
NOTE: When replacing, boiler tee must be
mounted vertical to prevent a blockage due
to condensate build-up.
A. Set VOM to read resistance (ohms) and
connect meter leads to Aux LLCO probe
and boiler. If there is any measurable
resistance, remove and clean the Aux
LLCO probe.
B. Replace the probe and check resistance
again. If resistance is still present, install a
replacement probe.
C. Verify resistance measurement with new
probe installed.
7. Turn power switch on and allow boiler to begin
filling. Do not press the reset switch to start
heating.
8. With water below the lowest visible level in sight
glass (below Aux LLCO probe) and boiler in
initial fill state:
A. Verify Aux LLCO LED is not lit on the Aux
water level control board.
4. Test LLCO circuit on water level control board.
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
B. Verify Low Water light is lit (front control 3. Press reset switch and verify high pressure light
panel).
turns off.
C. Verify 120VAC is on Aux LLCO COM, and
0 volt is on Aux LLCO N.O. contacts.
4. When green ready light comes on, press reset
switch to begin heating (low water light turns
off).
9. When water level reaches Aux LLCO probe as
boiler continues to fill:
A. Allow boiler to fully pressurize. Cycling
pressure switch opens and heating stops.
A. Verify Aux LLCO LED is lit on the auxiliary
low water board.
5. Turn one cooking compartment timer on to
exhaust steam from boiler.
B. Verify the green ready light is lit (front
control panel).
6. Monitor boiler pressure gauge for two complete
cycles. Note pressure at which the heat comes
on and goes off.
C. Verify 120VAC is on the Aux LLCO
common and normally open contacts of the
auxiliary water level control board.
The heat should come on at 10 PSI and go off
at 12 PSI.
10. Open the ball valve on probe housing assembly.
This will allow boiler to drain.
A. If pressure readings differ, continue with
procedure to adjust.
11. When water level is no longer visible in sight
glass and is below LLCO probe; Aux LLCO
circuit should activate.
7. Two pressure adjustment screws extend
through the top of switch cover. A clockwise
rotation increases pressure; a counter-
clockwise rotation decreases pressure.
A. Low water light turns on (front control
panel).
A. Turn the adjustment screw above right side
pointer to obtain the proper cut-out (off)
pressure setting.
B. Aux LLCO led turns off on the auxiliary low
water board.
C. Press reset switch to verify lockout
condition. Low water light should remain
on.
B. Turn the adjustment screw above the left
side pointer to obtain the proper cut-in (on)
pressure setting.
D. If lockout condition does not occur,
NOTE: The screw directly above the right side
pointer adjusts cut-out (off) and cut-in (on) set
points without changing the differential. The
screw directly above the left side pointer adjusts
cut-in (on) set point and changes the
differential.
immediately turn power switch off.
1) Disconnect power to machine.
2) Replace auxiliary low level cut-off
control and check for proper
operation.
8. Monitor boiler pressure gauge for two complete
cycles and note the pressure at which the heat
comes on and goes off.
E. If lockout condition is ok, verify the auxiliary
water level control circuit is functioning
properly.
A. If pressures are correct, pressure switch is
properly adjusted.
F. Close the ball valve on probe housing
assembly and allow boiler to fill.
B. If pressures are not correct, repeat the
adjustment for up to three attempts.
1) Verify low water light turns off (front
control panel).
9. If the above adjustment cannot be obtained,
install a replacement pressure switch and adjust
pressure settings as outlined in this procedure.
2) Press the reset switch and verify
auxiliary contactors A & C are
energized and boiler is heating.
CYCLING PRESSURE SWITCH
ADJUSTMENT
1. Access cycling pressure switch as outlined
under PRESSURE SWITCH CONTROL BOX
COMPONENTS in REMOVAL AND
REPLACEMENT OF PARTS.
2. Turn power switch on (boiler begins to fill).
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
NOTE: For every click of the adjustment wheel,
the pressure setting is changed approximately
1/8 PSI.
HIGH LIMIT PRESSURE
SWITCH ADJUSTMENT
NOTE: Make the adjustment in small
increments.
NOTE: Before the high limit pressure switch can be
adjusted, the cycling pressure switch must be
temporarily removed from the boiler control circuit.
This allows the boiler to pressurize above the normal
operating range. After the high limit pressure switch
is properly adjusted, the cycling pressure switch
must be returned to its normal operating
condition. Follow the procedure as outlined in the
steps below.
7. After adjusting high limit pressure switch, the
boiler pressure must be reduced to check the
pressure setting.
A. Remove left side boiler base panel to
access the manual ball valve on the probe
housing assembly.
WARNING: THE STEAMER AND ITS PARTS ARE
HOT. USE CARE WHEN OPERATING, CLEANING
OR SERVICING THE STEAMER. THE BOILER
CONTAINS LIVE STEAM. STAY CLEAR WHEN
OPENING THE VALVE.
1. Access cycling pressure switch as outlined
under PRESSURE SWITCH CONTROL BOX
COMPONENTS in REMOVAL AND
REPLACEMENT OF PARTS.
A. Remove cover from cycling pressure
switch.
B. Open the manual ball valve to release
boiler pressure and monitor the boiler
pressure gauge.
B. Connect a jumper wire between the two
electrical terminals to temporarily remove
the cycling pressure switch from the boiler
control circuit.
NOTE: High limit pressure switch resets at
approximately 12 PSI (not adjustable).
C. When pressure is reduced to
2. Reconnect power to machine and turn power
switch on (boiler begins to fill).
approximately 8 PSI, close the ball valve.
D. Press reset switch to reset the high
pressure safety circuit and begin heating
(high pressure light turns off).
3. Press reset switch and verify high pressure light
turns off.
4. When green ready light comes on, press reset
switch to begin heating (low water light turns
off).
8. Monitor boiler pressure gauge and note the
pressure at which the high limit pressure switch
opens.
NOTE: A pressure relief valve with a 15 PSI setting,
serves as back-up to the high limit pressure switch.
A. If pressure is correct, the high limit
pressure switch is properly adjusted.
5. Monitor boiler pressure gauge. Note pressure at
which the high limit pressure switch opens (high
pressure light turns on).
B. If pressure is not correct, repeat the
adjustment for up to three attempts.
9. If the above adjustment cannot be obtained,
install a replacement high limit pressure switch
and adjust as outlined in this procedure.
The switch should open at boiler pressures no
less than 14.5 PSI but no greater than 15.0 PSI
(MAX).
10. After the high limit pressure switch is properly
adjusted, disconnect power to machine and
allow boiler to blowdown/drain.
A. If pressure reading differs, continue with
procedure to adjust.
CAUTION: While making the adjustment, do not
press on the wheel with extreme force. The
switch may rotate and develop a leak at the
compression fittings or in some cases, the rear
lead wire may touch the control box and create
an electrical short.
11. Remove jumper wire from cycling pressure
switch to return the switch to its normal
operating condition.
12. Check for proper operation.
BOILER FILL AND COLD WATER
CONDENSER SOLENOID VALVES
6. Turn adjustment wheel to change high limit
pressure switch setting.
A. A counterclockwise rotation lowers the
pressure switch set point; a clockwise
rotation raises the pressure switch set
point.
1. Access boiler fill and cold water solenoid valves
as outlined under PRESSURE SWITCH
CONTROL BOX COMPONENTS in REMOVAL
AND REPLACEMENT OF PARTS.
2. Turn power switch on (boiler begins to fill).
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
3. To check boiler fill valve:
NOTE: If internal solenoid parts appear to be
damaged or worn, then replace the solenoid valve.
Do not reuse damaged or worn parts. No internal
solenoid parts are available as a service
replacement.
A. Verify 120VAC to solenoid valve coil.
B. If voltage is correct but valve is not opening
(little or no water flow), turn power switch
off and disconnect power to machine.
A. Check rubber seal on bottom of plunger.
B. Check plunger spring.
1) Remove lead wires from coil and
check for continuity.
C. Check O-ring in valve body.
D. Check ports in valve body.
2) If no continuity is measured, install a
replacement solenoid valve and check
for proper operation.
3) If continuity is measured, the coil is
good.
C. If voltage is not correct, check main water
level control board as outlined under
WATER LEVEL CONTROLS TEST.
4. To check cold water condenser valve:
NOTE: Valve should energize only during cooking
cycles and at boiler blowdown/drain.
A. Verify 120VAC to solenoid valve coil.
11. Reverse procedure to install and check for
proper operation.
B. If voltage is correct but valve is not opening
(little or no water flow), turn power switch
off and disconnect power to machine.
COLD WATER CONDENSER
THERMOSTAT ADJUSTMENT
1) Remove lead wires from coil and
check for continuity.
During a cooking cycle or boiler blowdown/drain, the
cold water condenser thermostat (N.O.) should
close and energize the cold water condenser
solenoid valve. The water from spray nozzle mixes
with the drain water in the condenser drain box to
reduce drain water temperature and condense
steam vapors.
2) If no continuity is measured, install a
replacement solenoid valve and check
for proper operation.
3) If continuity is measured, the coil is
good. Continue with procedure for
additional valve checks.
C. If voltage is not correct, check cold water
condenser thermostat as outlined under
COLD WATER CONDENSER
If excessive steam vapors are seen exiting the drain,
adjust the cold water condenser thermostat as
outlined below.
THERMOSTAT ADJUSTMENT.
1. Turn power switch off and allow boiler to
blowdown/drain.
5. To check valve ports for clogs or valve
component malfunction, continue with
procedure for disassembly and inspection of
internal components.
2. Access cold water condenser thermostat as
outlined under PRESSURE SWITCH
CONTROL BOX COMPONENTS in REMOVAL
AND REPLACEMENT OF PARTS.
6. Turn water supply off, disconnect water line
from valve body then remove solenoid valve.
3. Turn thermostat shaft fully counterclockwise to
energize the cold water condenser solenoid
valve.
7. Remove coil assembly from valve stem
8. Secure the valve body to keep it from turning.
A. Allow cold water to flow until condenser
drain box has completely cooled.
9. Scribe a line on stem nut to valve body for
proper re-tightening then remove stem locking
nut and remove the stem from valve body.
B. Slowly turn thermostat shaft clockwise until
thermostat opens and de-energizes the
solenoid valve. Turn shaft an additional 1/4
turn to prevent the thermostat from closing
near room ambient temperatures.
10. All parts are now accessible for inspection and
cleaning.
4. Check for proper operation.
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
HEATING ELEMENT TEST
COOKING COMPARTMENT
NOTE: Before proceeding with intake shut-off valve
adjustment, monitor boiler pressure gauge and verify
boiler is operating between 10-12 PSI. If boiler
pressure adjustment is necessary, refer to CYCLING
PRESSURE SWITCH ADJUSTMENT.
KW PER
ELEMENT ELEMENT
AMPS PER
OHMS PER
ELEMENT
VOLTAGE
208
240
9.0
9.0
14.4
12.5
6.3
14.4
19.2
76.8
12.4
10.8
14.4
57.6
Intake Shut-Off Valve Adjustment (Steam Flow)
1. Remove right side compartment panel.
480
9.0
208
10.5
12.0
12.0
12.0
16.9
19.3
16.7
8.3
2. Allow boiler to fully pressurize (heat turns off).
208
NOTE: The intake shut-off valve adjustment should
be made while boiler pressure is at the upper cycling
limit.
240
480
3. Turn both cooking compartment timers on.
4. Open the intake shut-off valve completely.
1. Values in the table are nominal.
Tolerance is +5/-10%.
NOTES:
2. Voltage values are @ 60HZ.
5. Slowly begin to close the intake shut-off valve
and monitor manifold pressure gauge. Adjust
the valve until manifold pressure gauge reading
is between 8-10 PSI.
3. Resistance values (ohms) are @ room
temperature. If heating elements are
above room temperature, the measured
resistance will be greater.
4. Each heating element has 3 separate
internal elements.
1. Access the heating elements as outlined in
REMOVAL AND REPLACEMENT OF PARTS.
2. Measure voltage at heating element terminals
and verify it against data plate voltage.
A. If voltage is incorrect, see
TROUBLESHOOTING.
B. If voltage is correct, continue with
procedure.
3. Check current draw (amps) through the heating
element lead wires.
NOTE: Checking current draw is the preferred
method over a resistance check when a clamp on
type amp meter is available.
A. If current draw is correct then heating
element is functioning properly. See table
for proper values.
B. If current draw is not correct, turn power
switch off and disconnect the electrical
supply.
6. Monitor manifold pressure gauge reading for
two complete boiler cycles.
1) Install a replacement heating element.
A. If the manifold pressure gauge reading
stays within tolerance while the boiler is
cycling, the intake shut-off valve is set
correctly.
C. If unable to check current draw, a
resistance check may indicate a
malfunctioning element.
1) Turn power switch off and disconnect
power to machine.
B. If the manifold pressure gauge reading is
outside of the tolerance repeat the
adjustment.
2) Remove lead wires from heating
element and check resistance (ohms).
See table for proper values.
7. Once the steam supply manifold pressure is set
correctly, turn both cooking timers off and install
right side compartment panel.
4. Check for proper operation.
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VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
3. Open door and check the door strikers’ slot for
Door Sealing Adjustment
horizontal alignment. The slot on door striker
must be kept horizontal for the door latch to
1. Check door gasket condition. If damaged or
worn, replace as outlined under COOKING
COMPARTMENT DOOR(S) in REMOVAL AND
REPLACEMENT OF PARTS.
catch on the door strikers slot and latch.
<
2. Loosen screws until the screw heads no longer
touch gasket plate.
3. Tighten screws until the screw heads touch
gasket plate and begin counting turns. Tighten
all screws approximately two turns.
4. Close the door and check for proper operation.
A. If necessary, tighten all screws an
additional 1/2 turn.
B. Repeat as necessary, tightening all screws
by 1/2 turn until the door closes properly
and no steam leaks are seen around
gasket seal.
Door Latch Adjustment
Should cooking compartment door jam and cannot
be opened, do not force or pry the door or damage
may occur.
Lift bottom of door at the handle end to disengage
latch. If door does not release, remove the right side
panel to access door striker.
4. Place a cloth over the door striker to protect the
slot. Secure the door striker close to its base to
keep it from turning and tighten striker nut.
The door striker mounting nut is located behind the
front panel of cooking cavity. Remove striker nut
from striker to release door.
NOTE: Do not over tighten as the striker will begin to
turn and change alignment.
5. Check for proper operation.
Remove any burrs on door striker that may cause
door latch to stick. Reinstall door striker and adjust
as outlined below.
CAUTION: When installing, do not damage the
slot in the door striker or door may not latch
properly.
To adjust:
1. Reinstall door striker with the slot pointing up
and hand tighten striker nut only.
2. Close door to center the door striker in the oval
mounting hole.
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VHX SERIES STEAMER - ELECTRICAL OPERATION
ELECTRICAL OPERATION
COMPONENT FUNCTION
CABINET BASE BOILER CONTROLS
Power Switch . . . . . . . . . . . . . . . . Controls 120VAC to the boiler control circuit.
Reset Switch (Manual) . . . . . . . . . Resets the low water level safety circuit on initial startup or the occurrence of
a low water condition. Also, resets the high pressure level safety circuit on
initial startup or the occurrence of a high pressure condition which allows
heating to start.
Boiler Fill Valve . . . . . . . . . . . . . . . Allows water flow to the boiler when energized thru HL-3 contacts on the
water level control.
Cold Water Condenser
Valve . . . . . . . . . . . . . . . . . . . . . . . Allows cold water to spray thru a nozzle inside the condenser drain box to
condense steam and cool the hot water before discharging into the drain.
Cold Water Condenser
Cycling Thermostat . . . . . . . . . . . Regulates cold water spray inside the condenser drain box during a cooking
cycle or boiler blowdown/drain.
Cycling Pressure Switch . . . . . . . Regulates boiler pressure between cut-out (off) and cut-in (on) pressure
settings of switch.
High Limit Pressure Switch . . . . . Prevents boiler from reaching pressures above 15 PSI by removing power
from heating circuit. The high limit automatically resets at approximately 12
psi (green ready light on).
Main Water Level Control . . . . . . A dual function control that allows water to fill and maintain the proper level
in the boiler, providing differential level control; and removes power from
heating circuit if water level drops too low, providing low level cut-off
protection. The control uses three different probe lengths to monitor water
level (high level HL, low level LL, low level cut-off LLCO).
Auxiliary Water Level Control . . . A back up to the low level cut-off on the main water level control. Protects
boiler and heating system components from a low water cut-off condition by
opening the 120VAC voltage path to the heating circuit. The control uses a
single probe to monitor water level (auxiliary low level cut-off Aux LLCO).
Relay Board . . . . . . . . . . . . . . . . . . Provides a centralized location for wire harness connections and power
transfer thru board relays (K1-K4) to the steamer controls. Also, provides
voltage test points (T1-T7) for verifying voltage to relay coils, N.O. relay
contacts closed, control panel lights and auxiliary contactor coils.
NOTE: The relay’s below are mounted on the relay board and are individually replaceable.
K1 Relay . . . . . . . . . . . . . . . . . . . . Energized when water level reaches the Aux LLCO probe (water level
condition satisfied).
K2 Relay . . . . . . . . . . . . . . . . . . . . Energized when high limit pressure switch is closed (high limit pressure
condition satisfied). When K1 & K2 are energized, ready light (green) will be
on.
K3 Relay . . . . . . . . . . . . . . . . . . . . Energized when K1(2) N.O. contacts close and reset switch is activated.
When K3 is energized, K3(2) N.O. contacts close and low water light turns
off.
K4 Relay . . . . . . . . . . . . . . . . . . . . Energized when K2(2) N.O. contacts are closed and reset switch is
activated. When K4 is energized, K4(2) N.O. contacts close and high
pressure light turns off. When K3 and K4 are energized, power is supplied to
auxiliary contactors A & C.
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Supply Voltage Transformer . . . . Provides 120VAC to the boiler control and cooking compartment control
circuits.
Cycling Contactors B & D . . . . . . Supplies line voltage to one side of heating elements thru cycling pressure
switch N.C. contacts and LLCO-1 N.O. contacts.
Auxiliary Contactors A & C . . . . . Supplies line voltage to energize the heating elements thru relay K3 & K4
N.O. contacts.
Heating Elements . . . . . . . . . . . . . Heats water in boiler to generate steam.
Blowdown/Drain
Solenoid Valve . . . . . . . . . . . . . . . N.O. valve that closes when energized by the power switch to allow boiler to
fill and pressurize. When de-energized, valve opens to blowdown and drain
the boiler contents.
COOKING COMPARTMENT CONTROLS
The upper section of the steamer consists of two separate cooking compartments. Each compartment functions
independently with its own set of controls. Power is supplied to the controls only after the steam pressure rises
above the compartment pressure switch setting to close the N.O. contacts.
Ready Light (Green) . . . . . . . . . . . When lit, indicates steamer is ready to cook.
Cooking Light (Red) . . . . . . . . . . . When lit, indicates steamer is in a cooking cycle.
Cooking Timer . . . . . . . . . . . . . . . Use to set cooking time between 0-60 minutes. When timer is set, energizes
the steam solenoid valve to allow steam into the cooking compartment.
When time expires, energizes buzzer until turned off.
Buzzer . . . . . . . . . . . . . . . . . . . . . . Signals end of a cook cycle, must be turned off manually.
Door Switch . . . . . . . . . . . . . . . . . Removes power to cooking timer. If time is dialed on cooking timer and
compartments are steaming, removes power to steam solenoid valve when
compartment door is opened.
Steam Solenoid Valve . . . . . . . . . When energized, opens to allow steam into the cooking compartment
(normally closed valve).
Compartment Pressure Switch . . Supplies power to cooking compartment controls, after steam pressure rises
above approximately 3 psi to close the pressure switch. The pressure switch
remains closed as long as steam pressure is above the stated pressure.
Page 25 of 48
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VHX SERIES STEAMER - ELECTRICAL OPERATION
COMPONENT LOCATIONS
Boiler Base Controls
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Boiler Base Controls Continued
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Cooking Compartment Controls
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
When the water level drops below the low level (LL)
WATER LEVEL CONTROLS
probe, power is removed from the inverse latching
relay, the HL relay energizes through ILR-2 and HL
contacts change state. The boiler fill solenoid is
energized through HL-1 to refill the boiler and the HL
LED is lit. The HL relay and LED will toggle on and
off during a cooking cycle as needed.
Low Level Cut-Off & Differential Control
The steamer is equipped with three water level
sensing probes (high, low and low level cut-off) and
a water level control board. The water level control
board performs two functions: 1) Provide low level
cut-off protection to shut off the heat source in case
the water level drops below the low level cut-off
(LLCO) probe. 2) Perform as a differential level
control to maintain the water level between the low
and high water level probes.
The water level control (WLC) board has input
voltage (120VAC) across terminals 11 and 12 which
powers the primary side of the transformer. On one
side of the transformer secondary, power is provided
to the control by a series path through chassis
ground (terminal 10). The other side of the
transformer secondary (12VAC) is attached to the
probe that directs power to the other side of WLC
board relay coils (LLCO and HL) and to the inverse
latching relay (ILR) electronic circuit on the WLC
board. As water enters the boiler, it becomes part of
the WLC board circuit. When the water level in the
boiler reaches a probe, that circuit is completed.
The inverse latching relay of the WLC board is de-
energized, leaving the ILR-1 (N.O.) and ILR-2 (N.C.)
contacts in their shelf state.
When the main power switch is turned on, power is
supplied to the WLC board which energizes the high
level (HL) relay, closes HL-1 normally open contacts,
and illuminates the HL relay LED. With the HL-1
contacts closed, the boiler fill solenoid is energized
and water begins filling the boiler.
When the water level reaches the low level cut-off
(LLCO) probe, the LLCO relay is energized and
illuminates the LLCO LED. With the LLCO-1 contacts
closed, the heat source can be energized provided
the auxiliary control(s) in the heating circuit are
satisfied. The LLCO relay will remain energized and
its LED will stay lit until the water level in the boiler
drops below the LLCO probe.
When the water level reaches the low level (LL)
probe, power to terminal 2 on the WLC board is
present but no switching occurs.
After the water level reaches the high level (HL)
probe, the inverse latching relay of the WLC board is
energized and locked through the low level probe
(LL) and ILR-1 contacts. With ILR-2 contacts open,
HL relay is de-energized and the HL LED goes out.
With the HL-1 contacts open, the boiler fill solenoid is
de-energized, stopping the flow of water into the
boiler.
Page 29 of 48
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Auxiliary Low Level Cut-Off
This control serves as a safety backup to the main
water level control (WLC) board to meet CSD-1 code
requirements. The operation of the auxiliary control
board is identical to the low level cut-off (LLCO)
function of the main WLC board but performs a
single function: 1) Provide auxiliary low level cut-off
protection to shut off the heat source in case the
water level drops below the auxiliary low level cut-off
(Aux LLCO) probe. A single Aux LLCO probe,
identical to the LLCO probe on the main WLC board,
is connected to the auxiliary control.
The auxiliary control board has input voltage
(120VAC) across terminals 11 and 12 which powers
the primary side of the transformer. On one side of
the transformer secondary, power is provided to the
control by a series path through chassis ground
(terminal 10). The other side of the transformer
secondary (12VAC) is attached to the Aux LLCO
probe that directs power to the other side of the
auxiliary control board relay (LLCO). As water enters
the boiler, it becomes part of the auxiliary water level
control’s circuit. When the water level in the boiler
reaches the Aux LLCO probe, the circuit is
completed.
When the main power switch is turned on, power is
supplied to the auxiliary control board but no
switching occurs. Also, the low water level indicator
light (amber) on the boiler base control panel comes
on.
When the water level reaches the auxiliary low level
cut-off (Aux LLCO) probe, the LLCO relay is
energized (LLCO-1 close) and the LLCO LED lights
up. The LLCO relay will remain energized and its
LED will stay lit until the water level in the boiler
drops below the Aux LLCO probe.
When the boiler stops filling, press the manual reset
switch on the boiler base control panel. This turns off
the low water light and energizes the heat source.
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
RELAY BOARD
Layout, Legend & Diagnostic Test Points
The relay board provides a centralized location for wire harness connections and power transfer through board
relays (K1-K4) to the other steamer controls. Also, provides for condition or component troubleshooting by utilizing
seven voltage test points (T1-T7) on the board to verify the voltage status for the condition or component in the
operating sequence. When the condition for the component<s voltage measurement is satisfied or activated,
120VAC can be measured between T1 (ref.) and T2 thru T7 test points to indicate whether the condition or
component is receiving voltage to energize and operate. If the voltage is not present, then the condition or
component has not been energized or is not activated.
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Schematic
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
I.
120VAC to common terminal on WLC
LLCO-1 contacts thru cycling pressure
switch (N.C.).
SEQUENCE OF OPERATION
Refer to schematic diagram AI1385 for the electrical
sequence of operation.
3. Water level reaches LLCO probe for the main
water level control and AUX LLCO probe for the
auxiliary water level control.
Initial Fill and Preheat
1. Conditions.
A. LLCO relay on water level control
energizes, LLCO-1 contacts (N.O.) close
A. Boiler connected to correct supply voltage
and is properly grounded.
1)
LED on board lights.
1) Supply voltage transformer energized
and 120VAC is output from
2) Cycling contactors B & D energized.
Heating elements remain de-
energized until manual reset switch
pressed.
transformer secondary.
2) 120VAC to compartment controls and
one side of the power switch.
B. AUX LLCO relay on AUX water level
control energizes, AUX LLCO-1 contacts
(N.O.) close.
B. Power switch off.
C. Cycling pressure switch closed.
D. High limit pressure switch closed.
1) LED on board lights.
2) K1 is energized thru AUX LLCO-1
N.O. contacts.
E. Cold water condenser (CWC) thermostat
open.
a. K1(1) N.O. and K1(2) N.O. close.
F. Automatic blowdown/drain valve (A.B.D.)
open and boiler empty.
b. Ready light on manual reset
switch lit thru K1(1) N.O.
contacts.
G. Water supply valve(s) on.
2. Turn power switch on.
NOTE: The LLCO and AUX 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.
A. Automatic blowdown/drain valve (N.O.) is
energized and closes.
B.
Water level control (WLC) energized.
NOTE: The manual reset switch could be
pressed to energize the heating elements but
it’s preferred to let the boiler fill the to the high
level before continuing.
1) High level (HL) relay energized, HL-3
N.O. contacts close.
a. Boiler fill solenoid energized,
water begins filling the boiler (fill
time 4-11 min.).
4. Water reaches LL (low level) probe.
5. Water reaches HL (high level) probe.
A. Boiler fill solenoid is de-energized.
B. HL LED goes out.
2) LLCO-1 N.O. contacts remain open.
3) HL LED lit.
C. Auxiliary water level control (AUX WLC)
energized.
6. Manual reset switch pressed.
A. K3 is energized.
1) AUX LLCO-1 N.O. contacts remain
open.
NOTE: Relay K3 remains energized through
D. 120VAC to common relay terminal on
K1(1) N.O., K3(1) N.O., K3(1) N.C., K3(2)
N.O. , K4(1) N.O., K4(1) N.C contacts.
K3(1) N.O. latching circuit.
1) K3(1) N.O. contacts close and K3(1)
N.C. contacts open.
E. Low Water light lit thru K3(1) N.C.
F. High Pressure light lit thru K4(1) N.C.
2) Low water light goes out.
3) K3(2) N.O. contacts close.
G. K2 energized through the high limit
pressure switch (N.C.).
a. 120VAC to common side of
K4(2) N.O. contacts.
1) K2 contacts K2(1) N.O. & K2(2) N.O.
close, no power transferred.
B. K4 is energized.
NOTE: Relay K4 remains energized through
K4(1) N.O. latching circuit.
H. 120VAC to common terminal on AUX
LLCO-1 contacts.
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VHX SERIES STEAMER - ELECTRICAL OPERATION
1) K4(1) N.O. contacts close and K4(1)
2) Boiler fill valve is de-energized.
3) HL LED goes out.
N.C. contacts open.
2) High pressure light goes out.
3) K4(2) N.O. contacts close.
4. The water refill cycle will occur whenever the
water level is below the low level probe and will
not affect the operation of either the preheat or
cook cycle.
a. AUX contactors A & C energized,
heating elements powered.
Boiler Blowdown/drain
NOTE: 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 and
1. Power switch turned off.
A. Automatic blowdown valve (N.O.) is de-
energized and valve opens to drain the
boiler.
condensing any steam vapors before
exiting the drain. The CWC solenoid is
powered through the CWC cycling
thermostat.
B. Power is removed from all components
except cold water condenser (CWC)
thermostat and solenoid valve. The CWC
thermostat cycles as necessary to lower
the discharge temperature of the water and
condense steam going into the drain.
7. Boiler steam pressure reaches upper limit set
point of 12 PSI (Approx. 15 minutes).
COOKING COMPARTMENT CONTROLS
1. Conditions.
A. Cycling pressure switch opens.
1) Cycling contactors B & D de-
energized and power is removed from
heating elements.
A. Doors shut (closes the N.O. door switch
contacts).
8. Boiler steam pressure drops below lower limit
set point of 10 PSI and the cycling pressure
switch closes.
B. Cooking timers off.
C. Compartment pressure switch contacts
open.
A. Cycling pressure switch continues to cycle
between the upper and lower set point
limits. This energizes and de-energizes the
heating elements to maintain pressure in
the boiler.
2. With boiler at operating pressure.
A. Cooking compartment pressure switch
closes (approx. 3 PSI).
1) Cooking compartment ready light
(green) comes on.
This sequence continues until one of the
following occurs:
3. Start a cook cycle.
1) Power switch is turned off.
A. Insert product into steamer and close door.
B. Set a cook time.
2) Boiler water level drops below the
LLCO probe for the main water level
control and the AUX LLCO probe for
the auxiliary water level control.
NOTE: On initial startup, if a cooking timer is set
immediately after the ready light comes on,
steam solenoid chattering will be heard (oil
canning) and the ready lights will flash for
several seconds. This condition is caused by
the manifold steam pressure being on the fringe
of the pressure switch set point. When a cook
timer is set, the compartment steam solenoid
valve opens causing the manifold steam
pressure to drop, slightly below the pressure
switch set point. At the same time, steam
pressure is still increasing in the boiler. This
opposing condition causes a pressure bounce
to occur. After the steam pressure passes
approximately 4 psi this condition subsides.
During normal operation, this condition will not
be seen.
3) Boiler pressurizes to 15 PSI, causing
the high limit pressure switch to open.
Water Refill (After Initial Fill)
1. Water level drops below low level probe (LL).
A. HL relay is energized.
1) HL-3 (N.O.) contacts close.
2) Boiler fill valve is energized.
3) HL LED comes on.
2. Water reaches LL (low level) probe.
3. Water reaches high level probe.
A. HL relay is de-energized.
C. Contacts 1/3 of cook timer close and timer
motor is energized.
1) HL-3 (N.O.) contacts open.
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
1) Compartment steam solenoid valve
energized and steam begins to enter
the compartment.
2) Ready light (green) goes out and
Cooking light (red) comes on.
NOTE: Steam should not be seen entering
either compartment until a cook time is set.
This energizes the steam solenoid valve of
the cooking compartment to allow steam
flow.
4. Time expires on timer.
A. Timer contacts 1/3 open, timer motor de-
energized.
B. Steam solenoid valve de-energizes,
stopping the flow steam into compartment.
C. Timer contacts 4/1 close and energize
buzzer until manually turned off.
D. Cooking light (red) goes out and Ready
light (green) comes on.
5. Timer manually turned off.
A. Contacts 1/4 open.
B. Alarm Buzzer de-energized and stops
buzzing.
6. Steamer reverts to preheat cycle until time is
dialed on timer and the door is shut, water level
drops below low level cut-off probe or the power
switch is turned off.
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VHX SERIES STEAMER - ELECTRICAL OPERATION
SCHEMATICS
Boiler Base Controls
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Cooking Compartment Controls
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VHX SERIES STEAMER - ELECTRICAL OPERATION
WIRING DIAGRAMS
Boiler Base Controls
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Heating Element Circuits
F25154 (February 2004)
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VHX SERIES STEAMER - ELECTRICAL OPERATION
Cooking Compartment Controls
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VHX SERIES STEAMER - TROUBLESHOOTING
TROUBLESHOOTING
BOILER BASE CONTROLS
SYMPTOM
POSSIBLE CAUSES
Steamer does not operate, low water light 1. Main circuit breaker off; or control circuit fuse F1 or F2 open.
and high pressure lights not lit.
2. Supply voltage incorrect.
3. Supply voltage transformer - jumper missing or incorrect
location; or transformer inoperative.
4. Power switch malfunction.
Steamer on, cannot reset low water
1. Boiler fill water off or filtering system clogged.
condition. Low water light lit, ready light
not lit, water level not visible in sight glass.
2. Boiler blowdown/drain valve stuck open or malfunction.
3. Manual blowdown valve open on water level probe housing.
4. Lime scale build-up on water level probes.
5. Water level control board - ground connection open, not
receiving power or malfunction.
6. Boiler fill valve clogged or malfunction.
7. Auxiliary water level control board - ground connection open,
not receiving power or malfunction.
8. Reset switch malfunction.
9. K1, K3 relays not seated properly or malfunction.
10. Water too pure for probes to properly conduct electricity.
11. Interconnecting wiring malfunction.
Steamer on, cannot reset low water
condition. Low water light lit, ready light
not lit, water level visible in sight glass.
1. Ground connection open on auxiliary water level control board.
2. Lime scale build-up dried on AUX LLCO probe.
3. Auxiliary water level control board not receiving power or
malfunction.
4. Reset switch malfunction.
5. K1, K3 relays not seated properly or malfunction.
6. Interconnecting wiring malfunction.
Steamer on, cannot reset high pressure
condition. High pressure light lit, pressure
gauge indicating 15PSI.
1. Cycling pressure switch out of adjustment or malfunction.
2. High limit pressure switch out of adjustment or malfunction.
3. Reset switch malfunction.
4. K2, K4 relays not seated properly or malfunction.
5. Steam trap malfunction.
6. Interconnecting wiring malfunction.
Boiler operates but pressures are below
the normal cycling range of 10-12 PSI.
1. Manual blowdown valve on water level probe housing open.
2. Boiler blowdown valve clogged and not fully closing.
3. Supply voltage incorrect.
4. Cycling pressure switch out of adjustment or malfunction.
5. Heating elements not wired correctly.
6. Contactor(s) malfunction.
7. Heating element malfunction.
8. Steam trap malfunction.
9. Excessive load on boiler due to other equipment connected to
steam line (outlet from boiler).
F25154 (February 2004)
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VHX SERIES STEAMER - TROUBLESHOOTING
POSSIBLE CAUSES
SYMPTOM
Condenser drain box leaking.
1. Grommets or cover panel gasket not sealing.
2. Clog in drain line plumbing.
3. Drain restricted due to drain pipe size below 1-1/4" NPT.
4. Drain extension plumbing not at the proper slope or plumbing
too lengthy.
5. Steamer drain not plumbed to an open air gap drain.
6. Steamer draining while under pressure and relief valve opening
at the same time (flooding drain box).
7. Cold water condenser spray is over spraying.
8. Cold water condenser cycling thermostat out of adjustment or
malfunction.
Excessive steam vapors exiting from
drain.
1. Water supply for cold water condenser line off or inline strainer
clogged.
2. Cold water condenser solenoid not receiving power, clogged or
malfunction.
3. Clogged spray nozzle (condenser drain box).
4. Water supply pressure high; or high pressure in line due to
water hammer, causing improper valve operation.
5. Cold water condenser thermostat out of adjustment or
malfunction.
Heat coming on without water in boiler
(Dry firing).
1. Lime scale build-up on water level probes.
2. Retention of water in probe housing (three probe assembly or
single AUX LLCO probe).
3. Air equalization tubes clogged.
4. Water level control malfunction.
5. Auxiliary water level control malfunction.
6. Reset switch malfunction.
7. K1, K2, K3, K4 relays malfunction.
8. Relay board malfunction.
Excessive time for boiler to reach
operating pressure (over 15 min.).
1. Supply voltage incorrect.
2. Heating elements not wired correctly.
3. Contactor(s) malfunction.
4. Water supply off or low pressure, filtering system clogged,
boiler fill valve clogged or malfunction.
5. Manual blowdown valve on water level probe housing open.
6. Boiler blowdown/drain solenoid valve clogged and not fully
closing.
7. Steam trap malfunction (stuck open).
8. Pressure relief valve leaking (pressure below 15PSI).
9. Cooking compartment steam solenoid valve clogged and not
fully closing.
10. Excessive load on boiler due to other equipment connected to
steam line (outlet from boiler).
11. A heavy build-up of scalants has coated the interior of the
boiler, creating an insulating effect.
Page 43 of 48
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VHX SERIES STEAMER - TROUBLESHOOTING
POSSIBLE CAUSES
SYMPTOM
Steamer on, boiler will not heat. Reset
switch activated, low water light and high
pressure light not lit, ready light lit.
1. Reset switch malfunction.
2. Water Level Control malfunction.
3. Cycling pressure switch out of adjustment or malfunction.
4. High limit pressure switch out of adjustment or malfunction.
5. K3, K4 relays malfunction.
6. Relay board malfunction.
7. Contactor(s) malfunction.
8. Interconnecting wiring malfunction.
Pressure relief valve opening or leaking.
Steam output low or slow cooking.
1. Pressure relief valve malfunction.
2. Cycling pressure switch out of adjustment or malfunction.
3. High limit pressure switch out of adjustment or malfunction.
1. Cooking Compartments.
A. Blocked steam injector ports. Open door, press door switch
button and verify good steam flow into compartment.
B. Steam solenoid valve clogged or malfunction.
C. Steam intake shut-off valve not adjusted properly.
2. Boiler Base.
A. Cycling pressure switch out of adjustment or malfunction.
B. Steam header line (supply) blockage.
C. Excessive amount of water in condensate tube loop from
boiler to pressure controls.
D. Pressure relief valve leaking.
E. Excessive steam supply line leaks.
Steamer leaks water.
1. Water, steam or drain line connections loose (top or base).
2. Heating element gasket not sealing.
3. Heating element mounting plate not sealing.
4. Gauge glass fittings loose.
Boiler water level too high, more than 1"
visible in sight glass.
1. Boiler fill valve malfunction.
2. Water level probes not wired correctly.
3. Lime scale build-up on HL probe.
4. Water level control malfunction.
Boiler does not fill or is slow to fill.
1. Boiler fill water off or filtering system clogged.
2. Manual blowdown valve on water level probe housing open.
3. Boiler fill valve not receiving power, clogged or malfunction.
4. Boiler blowdown/drain valve clogged and not fully closing.
5. Air equalization tubes clogged.
6. Water level control malfunction.
F25154 (February 2004)
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VHX SERIES STEAMER - TROUBLESHOOTING
COOKING COMPARTMENT CONTROLS
SYMPTOM
POSSIBLE CAUSES
Cooking compartments do not operate.
1. No power to cooking compartment controls.
2. Pressure in boiler is below compartment pressure switch
setting.
3. Manual intake shutoff valve in the off position.
4. Door switch malfunction.
5. Timer malfunction.
6. Malfunctioning pressure switch in compartment.
7. Interconnecting wiring malfunction.
Steam generated inside compartment
when timer is off.
1. Steam supply solenoid not fully closing (clogged or dirty).
2. Timer contacts 1 & 3 closed.
Timer motor does not run.
1. Door open or door switch malfunction.
2. Timer not receiving power or malfunction.
Door not closing properly.
1. Door latch assembly malfunction or out of adjustment.
2. Striker adjustment.
Door won’t open.
1. Latch won’t release.
Buzzer not operating.
1. Timer malfunction.
2. Buzzer malfunction.
Compartment leaks water around door or 1. Compartment drain screen clogged.
water accumulating in compartment .
2. Door out of adjustment.
3. Drain line obstructed or not to an open air gap drain.
4. Worn or damaged door gasket.
5. Steamer not level.
Steam leaks around door.
1. Door out of adjustment.
2. Worn or damaged door gasket.
3. Drain line obstructed or not to an open drain.
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VHX SERIES STEAMER
– NOTES –
F25154 (February 2004)
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VHX SERIES STEAMER
– NOTES –
Page 47 of 48
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VHX SERIES STEAMER - CONDENSED SPARE PARTS LIST
CONDENSED SPARE PARTS LIST
VHX24E, VHX24E5, MHB24E
BOILER BASE
PART NUMBER
DESCRIPTION
Element, 9kw 208V
NOTES
855051-1
855051-2
855051-3
855051-4
855051-5
855051-6
855051-7
881237
Element, 9kw 240V
Element, 9kw 480V
Element, 10.5kw 208V
Element, 12kw 208V
Element, 12kw 240V
Element, 12kw 480V
Fuse, 10 Amp 600v Time Delay
Fuse Holder
881236
880410
Gasket, heating element
Valve, Pressure Relief 15 psi
Valve, Cold Water Condenser and Boiler Fill
Switch, Pressure Cycling
Switch, Pressure High Limit
Thermostat, Condenser/drain Box
Contactor, 50 Amp
880413
817222
833488
851578-1
844062-1
854839-1
855223-1
855225-1
844070-1
844069-1
851613-1
855177-2
855177-3
853275-1
Relay Board (Includes relays)
Relays
Control, Aux. Low Water Board
Control, Low Water Board
Valve, Boiler Blowdown/drain
Transformer 240-480/120 250VA
Transformer 208/120 250VA
Switch Assembly (Power, Reset W/lights)
COOKING COMPARTMENT
DESCRIPTION
PART NUMBER
842049
NOTES
Door Switch
843833
Transducer
843832
Pressure Switch
411690-1
843836
Timer 60 Min 120v
Solenoid, Steam Inlet
Gasket, Door 3 Pan Compartment
Gasket, Door 5 Pan Compartment
844196
844385
F25154 (February 2004)
Printed in U.S.A.
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