Vulcan-Hart MHB24E Service Manual
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Vulcan-Hart MHB24E Service Manual

Vhx boiler base series high efficiency electric steamer
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Download this manual See also: Operation & Installation Manual
VHX24E SHOWN
This Manual is prepared for the use of trained Vulcan Service
Technicians and should not be used by those not properly qualified.
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,
determine if you have the necessary tools, instruments and skills
required to perform the procedure. Procedures for which you do not
have the necessary tools, instruments
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
service provider in your area, visit our website at www.vulcanhart.com.
A product of VULCAN-HART
VHX BOILER BASE SERIES
VHX24E
VHX24E5
MHB24E
- NOTICE -
the repair procedure you wish to perform
SERVICE MANUAL
HIGH EFFICIENCY
ELECTRIC STEAMER
ML-126852
ML-126853
ML-126857 (BASE ONLY)
and skills should be
LOUISVILLE, KY 40201-0696
F25154 (February 2004)
to

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Summary of Contents for Vulcan-Hart MHB24E

  • Page 1 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 service provider in your area, visit our website at www.vulcanhart.com. A product of VULCAN-HART...

  • Page 2: Table Of Contents

    TABLE OF CONTENTS GENERAL ................4 Installation, Operation and Cleaning .
  • Page 3 ELECTRICAL OPERATION ..............24 Component Function .

  • Page 4: General

    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.

  • Page 5: Boiler Code Descriptions

    Boiler Code Descriptions 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. CSD-1 Construction - Redundant controls in the...

  • Page 6: Electrical

    TOTAL MODELS 1 PHASE 208V 240V 208V 240V 480V VHX24E, VHX24E5, MHB24E NOTES: 1. Amperage values in the table are nominal. Tolerance is +5/-10%. 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.

  • Page 7: 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.

  • Page 8: Main Control Box Components

    Disconnect lead wires from other components as necessary then remove pressure switch mounting panel. Remove screws securing switch to panel. High limit pressure switch. Disconnect compression fittings from switch then remove from box. Boiler fill or cold water condenser valve. Turn water supply off and disconnect compression fittings from valve.

  • Page 9: Water Level Gauge Assembly

    To remove: Contactors. Release catch at the base of contactor and remove from DIN rail. Relays. Remove from socket. Relay Board. Compress locking tab on the board mounting standoffs and remove control board. Reverse procedure to install and check for proper operation.

  • Page 10: Heating Elements

    Insert one end of glass tube into top gauge fitting then align opposite end of tube with bottom gauge fitting. Lower the glass tube into bottom gauge fitting then center the tube between top & bottom gauge fittings. Hold glass tube in place and hand tighten the bottom packing nut then top.

  • Page 11: Heating Element Mounting Plate

    HEATING ELEMENT MOUNTING PLATE WARNING: DISCONNECT THE ELECTRICAL POWER TO THE MACHINE AND FOLLOW LOCKOUT / TAGOUT PROCEDURES. Remove heating elements as outlined under HEATING ELEMENTS. Loosen mounting hardware securing control panel to frame and lower the panel. On models with cooking compartments only, disconnect power cord from power switch box (rear of control panel).

  • Page 12: Boiler Assembly

    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.

  • Page 13: Descaler (Cathodic Protector)

    LEFT SIDE VIEW SHOWN 18. Separate union at boiler drain. 19. On models with cooking compartments: Remove the left and right access panels between the cooking compartments and boiler base. Disconnect flexible steam supply line from boiler tee to cooking compartments and remove the line.

  • Page 14: Cooking Compartment Door(S)

    To install: On the two replacement descalers, stretch the coiled wire (cathode) at the top to elongate the wire then form an open loop. Hang the descalers on the front horizontal support rod; one to the left of the heating elements and one to the right.
  • Page 15 Remove the nuts and spacers from the handle screws and remove the handle from the door. 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. Reverse procedure to install.

  • Page 16: 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.

  • Page 17: Water Level Probe Housing Blowdown

    Access the descalers (cathodic protectors) as outlined in REMOVAL AND REPLACEMENT OF PARTS. Inspect the two descalers hanging in boiler. 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"...
  • Page 18 Verify wire color connections are correct at probe numbers 50, 51 & 52, and at the water level control board. Turn power switch off. Remove probe assembly, clean lime scale build-up from the probes and compare probe lengths to drawing. Disconnect 3/8”...

  • Page 19: Cycling Pressure Switch Adjustment

    Verify Low Water light is lit (front control panel). Verify 120VAC is on Aux LLCO COM, and 0 volt is on Aux LLCO N.O. contacts. When water level reaches Aux LLCO probe as boiler continues to fill: Verify Aux LLCO LED is lit on the auxiliary low water board.

  • Page 20: High Limit Pressure Switch Adjustment

    HIGH LIMIT PRESSURE SWITCH ADJUSTMENT 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.

  • Page 21: Cold Water Condenser Thermostat Adjustment

    To check boiler fill valve: Verify 120VAC to solenoid valve coil. If voltage is correct but valve is not opening (little or no water flow), turn power switch off and disconnect power to machine. Remove lead wires from coil and check for continuity.

  • Page 22: Heating Element Test

    HEATING ELEMENT TEST KW PER AMPS PER VOLTAGE ELEMENT ELEMENT 14.4 12.5 10.5 16.9 12.0 19.3 12.0 16.7 12.0 NOTES: 1. Values in the table are nominal. Tolerance is +5/-10%. 2. Voltage values are @ 60HZ. 3. Resistance values (ohms) are @ room temperature.

  • Page 23: Door Sealing Adjustment

    Door Sealing Adjustment Check door gasket condition. If damaged or worn, replace as outlined under COOKING COMPARTMENT DOOR(S) in REMOVAL AND REPLACEMENT OF PARTS. Loosen screws until the screw heads no longer touch gasket plate. Tighten screws until the screw heads touch gasket plate and begin counting turns.

  • Page 24: Electrical Operation

    ELECTRICAL OPERATION COMPONENT FUNCTION 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 Boiler Fill Valve .

  • Page 25: Cooking Compartment Controls

    Supply Voltage Transformer ..Provides 120VAC to the boiler control and cooking compartment control Cycling Contactors B & D ..Supplies line voltage to one side of heating elements thru cycling pressure Auxiliary Contactors A &...

  • Page 26: Component Locations

    VHX SERIES STEAMER - ELECTRICAL OPERATION COMPONENT LOCATIONS Boiler Base Controls F25154 (February 2004) Page 26 of 48...
  • Page 27 VHX SERIES STEAMER - ELECTRICAL OPERATION Boiler Base Controls Continued Page 27 of 48 F25154 (February 2004)

  • Page 28: Cooking Compartment Controls

    VHX SERIES STEAMER - ELECTRICAL OPERATION Cooking Compartment Controls F25154 (February 2004) Page 28 of 48...

  • Page 29: Water Level Controls

    WATER LEVEL CONTROLS 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.

  • Page 30: Auxiliary Low Level Cut-Off

    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...

  • Page 31: Relay Board

    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.

  • Page 32: Schematic

    VHX SERIES STEAMER - ELECTRICAL OPERATION Schematic F25154 (February 2004) Page 32 of 48...

  • Page 33: Sequence Of Operation

    SEQUENCE OF OPERATION Refer to schematic diagram AI1385 for the electrical sequence of operation. Initial Fill and Preheat Conditions. Boiler connected to correct supply voltage and is properly grounded. Supply voltage transformer energized and 120VAC is output from transformer secondary. 120VAC to compartment controls and one side of the power switch.

  • Page 34: Cooking Compartment Controls

    K4(1) N.O. contacts close and K4(1) N.C. contacts open. High pressure light goes out. K4(2) N.O. contacts close. AUX contactors A & C energized, heating elements powered. NOTE: As boiler heats up and builds pressure, some by-pass water/steam is produced which runs into the steam drain box.
  • Page 35 Compartment steam solenoid valve energized and steam begins to enter the compartment. 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.

  • Page 36: Schematics

    VHX SERIES STEAMER - ELECTRICAL OPERATION SCHEMATICS Boiler Base Controls F25154 (February 2004) Page 36 of 48...

  • Page 37: Cooking Compartment Controls

    VHX SERIES STEAMER - ELECTRICAL OPERATION Cooking Compartment Controls Page 37 of 48 F25154 (February 2004)

  • Page 38: Wiring Diagrams

    VHX SERIES STEAMER - ELECTRICAL OPERATION WIRING DIAGRAMS Boiler Base Controls F25154 (February 2004) Page 38 of 48...
  • Page 39 VHX SERIES STEAMER - ELECTRICAL OPERATION Page 39 of 48 F25154 (February 2004)

  • Page 40: Heating Element Circuits

    VHX SERIES STEAMER - ELECTRICAL OPERATION Heating Element Circuits F25154 (February 2004) Page 40 of 48...

  • Page 41: Cooking Compartment Controls

    VHX SERIES STEAMER - ELECTRICAL OPERATION Cooking Compartment Controls Page 41 of 48 F25154 (February 2004)

  • Page 42: Troubleshooting

    SYMPTOM Steamer does not operate, low water light and high pressure lights not lit. Steamer on, cannot reset low water condition. Low water light lit, ready light not lit, water level not visible in sight glass. Steamer on, cannot reset low water condition.
  • Page 43 SYMPTOM Condenser drain box leaking. Excessive steam vapors exiting from drain. Heat coming on without water in boiler (Dry firing). Excessive time for boiler to reach operating pressure (over 15 min.). POSSIBLE CAUSES 1. Grommets or cover panel gasket not sealing. 2.
  • Page 44 SYMPTOM Steamer on, boiler will not heat. Reset switch activated, low water light and high pressure light not lit, ready light lit. Pressure relief valve opening or leaking. Steam output low or slow cooking. Steamer leaks water. Boiler water level too high, more than 1" visible in sight glass.

  • Page 45: Cooking Compartment Controls

    COOKING COMPARTMENT CONTROLS SYMPTOM Cooking compartments do not operate. Steam generated inside compartment when timer is off. Timer motor does not run. Door not closing properly. Door won’t open. Buzzer not operating. Compartment leaks water around door or water accumulating in compartment . Steam leaks around door.
  • Page 46 VHX SERIES STEAMER – NOTES – F25154 (February 2004) Page 46 of 48...
  • Page 47 VHX SERIES STEAMER – NOTES – Page 47 of 48 F25154 (February 2004)

  • Page 48: Condensed Spare Parts List

    Pressure Switch 411690-1 Timer 60 Min 120v 843836 Solenoid, Steam Inlet 844196 Gasket, Door 3 Pan Compartment 844385 Gasket, Door 5 Pan Compartment F25154 (February 2004) VHX24E, VHX24E5, MHB24E BOILER BASE DESCRIPTION COOKING COMPARTMENT DESCRIPTION NOTES NOTES Printed in U.S.A.

This manual is also suitable for:

Ml-126852Ml-126853Ml-126857Vhx24e5Vhx24e

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