Vulcan-Hart MHB24G, VHX24G5, VHX24G User Manual

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SERVICE MANUAL

VHX BOILER BASE SERIES

HIGH EFFI CIENCY GAS

STEAMERS

VHX24G ML-114795 VHX24G5 ML-126590 MHB24G ML-114954 (BASE ONLY)

VHX24G SHOWN

This Manual is prepared for th e use of trained Vulcan Service Technicians and should not be used by those not properly qu alif ied. If yo u have attend ed a Vulcan Service School for this product, you may be qualified to perform all the procedures described in this man ual.

Thi s manu al i s no t i nten ded to be al l en comp assi ng . I f you have not attende d a Vulcan S ervic e School for this produ ct , you should read, in its entirety, the repair procedure you wish to perform to determine if you have the necessary tools, instruments and skills required to perform the procedure. Procedures for which you do not have th e n ecessary too ls, in strument s and skills should be performed b y a trained Vu lcan Service Technician .

Reproduction or other use of this Manual, without the express written consent of Vulcan, is prohibited.

- NOTICE -

A product of VULCAN-HART LOUISVILLE , KY 40201-0696

F24700 (October 2001)

VHX SERIES STEAMERS

TABLE OF CONTENTS

GENERAL............................................................................. 4

Installation......................................................................... 4

Maintenance ....................................................................... 4

Cleaning .......................................................................... 4

Introduction ........................................................................ 4

Steam Cooking.................................................................. 4

Compartment Pan Capacity ........................................................ 4

Model Designations .............................................................. 4

Boiler Code Descr iptions .......................................................... 4

Boiler Control Styles.............................................................. 5

Water Conditi oning .................................................................. 6

Specifications ...................................................................... 6

Water Supply ................................................................... 6

Electrical ...................................................................... 6

Boiler Pressure.................................................................. 6

Gas Supply ..................................................................... 7

Tools ............................................................................. 7

STEAMER OPERATION.................................................................. 8

Cabinet Base Boiler .................................................................. 8

Cooking Compartment Controls......................................................... 8

Boiler Blowdown and Steamer Shut off ................................................... 9

Component Func tion ................................................................ 10

Cabinet Base Boiler Controls ...................................................... 10

Cooking Compartment Controls .................................................... 12

REMOVAL AND REPLACEMENT OF PARTS ................................................ 13

Component Locat ions ............................................................... 13

Cabinet Base Boiler Controls ...................................................... 13

Cooking Compartment Controls .................................................... 15

Water Level Controls

(Main or Auxiliary LLCO) ......................................................... 15

Relay Board....................................................................... 15

Water Level Gauge Assembly ......................................................... 16

Pressure Switches .................................................................. 16

Boiler Assembly.................................................................... 16

Boiler Fill and Cold Water Condenser Solenoi d V alves ...................................... 17

Pilot Gas Valve .................................................................... 17

Main Gas Valve.................................................................... 17

Burner Head Assembly .............................................................. 18

Complete Burner Assembly ........................................................... 18

Heat Exchanger .................................................................... 19

Cooking Compartment Door(s)......................................................... 21

SERVICE PROCEDURES AND ADJUSTMENTS .............................................. 23

Boiler............................................................................ 23

Inspection..................................................................... 23

Clean-Out ..................................................................... 23

Deliming...................................................................... 23

Descaler (Cathodic Protector ) ...................................................... 24

Water Level Probe Housing Blowdown .................................................. 24

Water Level Controls Test ............................................................ 25

Pressure Switches .................................................................. 27

Fill and Cold W ater Solenoid V alves .................................................... 28

Boiler Blowdown/drain Solenoid Valve .................................................. 29

Inline Water S trainer Cleaning ......................................................... 29

Main Burner Ignition Checks .......................................................... 30

F24700 (October 2001) Page 2 of 68

VHX SERIES STEAMERS

Air Pressure Switch Adjustment........................................................ 33

Gas Pilot Pressure Adjustment......................................................... 34

Gas Manifold Pressure Adjustment ..................................................... 36

Ignition Control Module Checks ........................................................ 37

Cooking Compartment............................................................... 39

Intake Shut-Off Valve Adjustment (Steam Flow)........................................ 39

Door Sealing Adjustment ......................................................... 39

Door Latch Adjustment........................................................... 40

ELECTRICAL OPERATION .............................................................. 41

Water Level Controls................................................................ 41

Low Level Cut-Off & Differential Control.............................................. 41

Auxiliary Low Level Cut-Off ....................................................... 42

Relay Board....................................................................... 43

Board Layout and LED Legend ..................................................... 43

Boiler Operational Status (LED Indicator) ............................................. 44

Sequence of O per ation .............................................................. 46

New Style Controls - Boiler........................................................ 46

Old Style Controls - Boiler ........................................................ 48

Cooking Compartment Controls .................................................... 50

Schematics ....................................................................... 52

Models Built After 5/25/00 (New Style Boiler Controls) ................................... 52

Models Built Befor e 5/25/00 (Old S tyle Boiler Controls) .................................. 54

Cooking Compartment Controls .................................................... 55

Wiring Diagrams ................................................................... 56

Models Built After 5/25/00 (New Style Boiler Controls) ................................... 56

Models Built Befor e 5/25/00 (Old S tyle Boiler Controls) .................................. 58

Cooking Compartment Controls .................................................... 60

TROUBLESHOOTING .................................................................. 61

CONDENSED SPARE PARTS LIST ........................................................ 68

F24700 (October 2001)Page 3 of 68

VHX SERIES STEAMERS - GENERAL

GENERAL

INSTALLATION

Refer to the Installation and Operation Manual for detailed installation instructions.

MAINTENANCE

Refer to the Installation and Operation Manual for specific maintenance instruct ions.

CLEANING

Refer to the Installation and Operation Manual for specific cleani ng instructions.

INTRODUCTION

Steam Cooking

Convection cooking in pressure-less steaming compartments will steam cook fresh foods or will steam def rost and cook froz en foods prov iding the maximum c olor, flav or and nutritional value with the least expenditure of energy and labor. T he pr essureless steaming compartm ents on the VHX series allows the operator to open and close the door, anytim e during a cooking cycle. T he steam supply will shut off when the door is opened, then re-start when the door is closed.

Compartment P an Capacity

PAN

DEPTH

(INCHES)

MODEL

VHX24G

NUMBER OF PANS

PER COMPARTMENT

24.0

32.5

Model Desi gnations

Boiler Code Descriptio ns

Vulcan-Hart incorporates redundant c ontrols in compliance with the CSD-1 controls and safet y devices for boiler construction on these High Efficienc y S team models. A Description of the c ode is listed below.

CSD-1 Constructi on electrical safety circuits that, i f tri pped, must manually be reset after the condit ion causing the trip subsides. These controls consist of - (1) dual function water level cycling and low level cut off control and ( 1) si ngle funct ion low water level cut-off control ( A ux LLCO) and a high pr essure rel ief switch in conjunction with a mechanical pr essure rel ief valve. A dditional ly, both circuits have indi vidual indicat or lights for low water and high pressure that will illuminate for a visual verification of the shutdown mode.

CSD-1 construction requires operator intervention i n the ev ent of a shutdown. The i ndicator l ights show the operator which safety system was shutdown.

- Redundant controls in the

61.0

34.0

VHX24G5

Pan Size 12" x 20"

F24700 (October 2001) Page 4 of 68

52.5

10 1.0

VHX SERIES STEAMERS - GENERAL

Boiler Control Styles

VHX Steamers manufactur ed usi ng the old style boiler controls ended on 5/19/00. Steamers that were in stock at the time of the boiler contr ol changeov er were removed and equipped with the new style c ontrols without recording t he serial number for track ing.

Refer to the pictures bel ow to differentiate between the old style and new style boiler controls.

F24700 (October 2001)Page 5 of 68

VHX SERIES STEAMERS - GENERAL

WATER CONDITIONING

Furnishing the boiler wit h treated water to reduce scale formation is import ant. Scale format ion will reduce steam out put, cause prematur e c omponent failure, and shorten equi pment life. Most water supplies contai n scale producing m inerals such as Calcium and Magnesium. As steam is generated, the mi nerals remai n and dissolve into the water. As the concentrat ion of these minerals i nc r eases past a certain point, they pr ec ipitate from the water and coat the inside of the boi ler, heating element s, and water level sensors. Because of the high temperat ure of these surf ac es, the precipitated minerals bake onto them and bec ome v er y difficult to remove.

This may c ause several probl ems:

1. Reduced heat transf er eff iciency.

2. Premature heating element failures.

3. False readings from water l evel sensors. These problem s are common to any manufacturer's

steamer regardless of design, but t hey c an all be minimized by furnishing the boiler with treated water.

Other factors affecting steam generati on ar e iron content, amount of c hlorination and dissolved gases.

SPECIFICATIONS

Water Supply

The fact that a water supply is potable is no guarantee that it is suitable for steam generation. The supply connect ion to the steam gener ator should be “treated” water and must be within t he guideli nes listed below. For dr ain water cooling only, an “untreated“ water suppl y c onnec tion should be used.

Supply pressure should be 20-60 psig In line strainer f or suppl y line (Not Supplied) Supply connection cold Total dissolved solids (TDS)* less than 60 ppm Total alkalinity less than 20 ppm Silica less than 13 ppm Chloride less than 30 ppm PH fact or 7 to 8

(*17.1 ppm = 1 grain of har dness)

Electrical

Voltage - 120/ 60/1 Amps - 3.0 (max)

The desired water propert ies can best be achieved by using a

system.

The water level probes in the boiler use ions i n the water to detect the water level.

demineralized or de-ionized water since it is "non conductive" and the water level can not be detected.

The use of strainers or remove mi nerals from the water.

Water supplies vary fr om state to state and from locati ons wit hin a state. Therefore, a

treatment specialist should be consulted

the installation of any steam generating equipment. Steamers that operate over a long peri od 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.

properly maintained water treatment

Do not use fully

non approved

filters will not

water

before

Boiler Pressu re

Operating - 8 to 10 psi Maximum - 15 psi

F24700 (October 2001) Page 6 of 68

Gas Supply

VHX SERIES STEAMERS - GENERAL

MODEL

VHX24G

VHX24G5

MHB24G

NOTE

Standard

INPUT

(BTU/HR)

NAT. PROP. NAT. PROP. NAT. PROP.

200,000 200,000 3.0 3.0 3.5 3.5 7.0 11.0 270,000 270,000 3.0 3.0 3.5 3.5 7.0 11.0 200,000 200,000 3.0 3.0 3.5 3.5 7.0 11.0 270,000 270,000 3.0 3.0 3.5 3.5 7.0 11.0 200,000 200,000 3.0 3.0 3.5 3.5 7.0 11.0 270,000 270,000 3.0 3.0 3.5 3.5 7.0 11.0

1. Output Boiler Horsepower (BHP): 4.3 BHP for 200,000 BTU; 5.5 BHP for 270,000 BTU.

2. Input BTU/HR difference is based on gas orifice size and air orifi c e size.

MANIFOLD

PRESSURE

(INCHES W.C. )

PILOT

PRESSURE

(INCHES W.C. )

NATURAL PROPANE

MINIMUM

RECOMMENDED

LINE PRESSURE

(INCHES W.C. )

RECOMMENDED

TOOLS

MINIMUM

MAXIMUM ALLOWED

14.0

Standard set of hand tools.



Volt-Ohm-Meter (VOM) with AC current tester.



(Any quality VOM wit h a sensit ivity of at least 20,000 ohm s per volt c an be used) Gas leak checking equipment.



Gas pressure manomet er



Temperat ure meter and t her mocouple.



Special

The recommended deli ming chemical for the water treatment system in use, for deliming of the boiler.



Contact Vul c an A uthorized Service Centers. Heat Exchanger Gasket (joi nt sealant strip, Teflon) P /N 854058-1.



F24700 (October 2001)Page 7 of 68

VHX SERIES STEAMERS - OPERATION

STEAMER OPERATION

CABINET BASE BOILER

Ensure that all utility connections to the steamer have been made and are turned ON and t hat the knob on the main gas valve is i n the ON positi on.

The VHX Series steam er s are CSD- 1 c ompliant and are equipped with amber colored lights on the boiler control panel for Hi gh P ressure and Low Water level that illuminate and stay on until the boiler is full and the manual reset switch pressed.

1. Turn power switch ON. A. Amber colored lights on the boiler control

panel for High Pressure and Low Water level will illuminate. and stay on until t he boiler is full and the reset switch is pressed.

B. Water will begin filling the boiler and the

blowdown solenoid v alve will close. The boiler shoul d fill, in four to eleven minutes.

C. As water fills the boiler, observe water

level gauge glass to verify that water i s i n boiler. See "WATER LEVEL GAUGE ASSEMBLY" in "COMPONENT FUNCTION” and COMPONENT LOCATION “ under "REMOVAL AND REPLACEMENT OF PARTS".

D. Onc e the water in the boiler reaches the

minimum level, the green ready light on the boiler control panel will illuminate.

NOTE: If the fill has stopped, one visible inc h of water should be in the gauge glass.

2. Press the reset switch on the boiler control panel.

A. Low water level safety circuit will be reset

and the Low Wat er lev el light (amber) will turn off.

B. High pressure safety circuit will be reset

and the High Pressure light (amber ) will turn off.

C. Sparking will begin three seconds later to

light the pilot bur ner.

1) I f the pilot burner lights, a signal is sent back through the igniti on c able indicat ing the presence of pilot burner flame and sparking stops.

2) I f pil ot burner flame is not established immedi ately, sparki ng will continue for 90 seconds. After that duration, the ignition control module will lock out and needs to be reset to start the pilot and main burner li ghting cycle again.

New Style Controls

Pilot gas valve operates on a "timer" circuit allowing gas flow to the pilot for approximately 15 seconds, during ignition trial, then turns off.

D. Main gas valve opens, burner ignites and

begins to heat the water in the boil er . After approximately 15 minutes, steam should be present for c ook ing product. O bserve that the boi ler pressure gauge indicates a steam pressure of 8- 10 psi before the burner shuts OFF.

3. The cycling pressure switch will maintain steam pressure in the boiler by cycling the main burner ON and OF F.

- Power to the

COOKING COMPARTMENT

CONTROLS

When the steam pressure in the c ook ing compartment manifol d reaches approximately 3 psi, the cooking compartment pressure switch closes, suppling power to the ot her c ook ing compart ment controls. The ready lights will illuminate and after approximately one minute, the steam pressure in the boiler will reach the upper limit of 10 psi. If the pressure drops below approximately 3 psi, the pressure switch will open, removing power fr om the controls.

NOTE:

immediatel y after t he ready light c omes on, steam solenoid chattering will be heard (oil canning) and the ready lights will flash for several seconds. This conditi on is caused by the mani fold steam pressure being on the “fringe” of the pressure switch set point. When a c ook timer is set, the compar tment steam solenoid valve opens causing the manifold st eam 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 approxim ately 4 psi this conditi on subsides. Dur ing normal oper ation, this conditi on will not be seen.

On initial startup, if a cooking ti mer is set

F24700 (October 2001) Page 8 of 68

VHX SERIES STEAMERS - OPERATION

1. With both timer knobs at the off posi tion, open the compartment doors and observe that no steam has entered the c ook ing compart ments, then close the doors.

2. Set both timer knobs at 2 minutes. The r eady lights will go off, the cooking lights will come on, and steam will begin to enter the compartments.

3. After one minute, open eac h door and observe that steam has ceased to enter each compartment, cooking lights go back to ready, and one minut e is remaining on each cook timer.

4. Close doors and steam generation and cook timing will resume. Observe the floor drain to ensure that live steam from compart ments is being cooled by cold water fr om the cold water condenser solenoid valve.

5. When timer k nobs reac h " 0" , buzzers will sound, steam generation will cease, cooking lights will go off and ready lights will come on. To silence buz z er s, turn timer knobs to off position.

BOILER BLOWDOWN AND

STEAMER SHUT OF F

Turn the steamer off at least once daily to bl owdown the boiler. This will aid in the removal of sediment and scale buil d- up in the boil er .

NOTE

: Boil er should be with-in normal operating

pressures.

1. Turn power switch OFF .

2. Boiler blowdown sequence starts. A. The blowdown/drain solenoid valve will be

de-energized and t he boiler will begin to drain.

B. The cold water condenser solenoid will

operate, as needed, to condense steam and to cool the water going into the dr ain.

6. During idle t ime or a cooking cycle, the heating system will cycle on and off as necessary to maint ain steam pressure in t he boiler.

7. Turn power switch off to remove power from the steamer.

A. Boiler blowdown starts.

F24700 (October 2001)Page 9 of 68

VHX SERIES STE A M E RS - COMPONENT FUNCTION

COMPONENT FUNCTION

CABINET BASE BOILER CONTROLS

Power Switch (ON/OFF) Reset Switch (Manual)

Boiler Fill Solenoid Valve

Cold Water Condenser Solenoid Valve

Blowdown/Drain Solenoid Valve

Cycling P ressure Switch

High Limit Pressure Sw itch

................. Allows cold water flow into the boiler blowdown drain box to condense

................. A normally open valve (N.O.) that closes to allow boiler to fill and

......... When turned ON, supplies power to the control cir c uit.

.......... Resets the low water level safety circuit on initial startup or the

......... Controls boiler pressure between prescribed limits by turning the heat

occurrence of a low water condition and allows the boil er to fill with water. Also, resets the high pressure lev el safety circuit on initial startup or the occurrenc e of a high pressure condition and all ows the gas ignition cycle to start.

........ Admits water to the boiler when dem anded by the water level control to

maintain the correct water level in the boiler.

steam and cool the hot water befor e its discharge int o the drain.

pressurize when power switch is turned ON and opens when power switch is turned off to blowdown and drain the boiler. This valve is plumbed into the drain line of the boiler.

source on and off.

...... Protects the boiler from pressures above 15 psi by removing power from

the heating ci rcuit. Thi s pressure setting is higher than the cycling pressure switch in order to t ur n off the heat source before the boiler pressure reaches its limit. A fter the pr essure drops below approximat ely 12psi, press the rest switch of the front control panel to rest the safety circuit.

Main Water Level Control

Auxiliary Water Level Control

Transformer Ignition Control Module

Main Gas Valve

Pilot Gas Valve

................... Provides 24VAC power to ignition control modul e and heating circ uit.

................ A gas solenoid valve that opens to allow gas flow to the main burner

................ A gas solenoid valve that opens to allow gas flow to the pilot to ignite the

........ A dual functioning control that allows water to fill and maintain the

......... Controls and m onitors gas heating. E ner gizes pilot valve coi l to supply

proper level in the boiler pr oviding dif ferenti al water level control; and shuts off the main gas valve if the water level drops too low providing low level cut-off protection. The water level control works by using three different probe lengths to moni tor the water level. The probes consist of a high level (HL) , low level (LL) and low water cut- off ( LLCO).

..... A back up to the low level cut-off on the main control. Protects the boiler

and heating system c omponents from a low water cut-off condition by opening the 24VAC volt age path to the heati ng system circuit. Al so, energizes the l ow water "l ight" on the front contr ol panel.

gas to pilot, generates spark to ignite gas at the pilot, monitors the presence of flame and energizes the main and pilot valve coi ls on the main gas valve upon a call for heat.

after the successful ignition of the pil ot burner when a call for heat is made.

main burner when a call f or heat is made. T he valve is energized by a tim e delay circ uit on the rel ay boar d dur ing ignit ion trial for approximately 15 seconds. New styl e c ontrols only.

Combustion Blower

F24700 (October 2001) Page 10 of 68

............ Provides forced air to the gas/air mixture for gas pilot and m ain burner

combustion.

VHX SERIES STE A M E RS - COMPONENT FUNCTION

Relay Board

................... Provides a centralized location for wire harness connections and power

transfer through board relays (K1-K 7) to the steamer controls. Also, provides a condition or component t r oubleshooting indicator by utilizing seventeen LED’S on the board to represent the status of the condi tion or component in the operation sequence. For an LED legend, see "RELA Y BOARD" under "E LE CTRICAL OPERATION". New style c ontrols only.

: The relay’s below are mounted on the relay board and are not

NOTE K1 Relay

...................... Energized when Aux LLCO is satisfied and turns ready light ( gr een) ON

if high limit pressure switch i s closed. Also, K1 allows K3 to be energized when the reset switch is pressed.

K2 Relay

...................... Energized when high li mit pressure switch is closed (high limit pressure

conditi on sat isfied). When K 1 & K 2 ar e ener gized, the ready light (green) will be ON.

K3 Relay

...................... When Aux LLCO is satisfied and the m anual reset switch is activat ed,

K3 is energized. When K 3 is energized, tur ns water error light OFF and allows the ignition sequence to begi n. K3 must be energi z ed for ignition sequence to begin.

K4 Relay

...................... Energized when K2 contacts are closed and manual reset switch is

activated. When K4 i s energized, the high pressure light is OFF. When K3 and K4 are both energized, power to the ignition system is supplied.

K5 Relay

...................... Energized when operating conditions are m et and reset switch is

activated. Pr ovides power to start combustion blower.

individual ly replaceable.

K6 Relay

...................... Energized by time delay circuit for approx imately 15 seconds. When K 6

and K7 are energized, power is supplied to the pilot gas valve.

K7 Relay

...................... Energized when pilot voltage (PV) f r om the ignition module is present.

Also used in the time delay c ircuit.

......................... Ignites to light the main burner upon a call f or heat.

Pilot Main Burner

................... Heats the water in the boiler to gener ate steam.

Water Level Gauge Assembly

............... Permits a visual confirmation the water level is being maintained in

boiler dur ing operation. The correct water l evel is approximately one visible inch in the glass. The manual valves at the top and bott om of this assembly m ust be full y open and only closed if the glass tube is damaged.

Water Inlet Valve (manual)

....... The water inlet valve is used to stop water flow to the steamer when the

steamer i s bei ng serviced. This valve should remai n open dur ing normal operation.

Inline Water Strainer

............ A "Y" strainer is installed upstream of the blowdown solenoid valve to

prevent forei gn matter from becoming lodged in the valve. A strainer (not supplied) shoul d also be installed in the water supply line to prevent forei gn matter from becoming l odged in the fill or cold water condenser solenoid valves and to keep unwanted partic les out of the system.

Pressure Relief V alve

........... A mechani c al device that opens to relieve steam pressure in the boiler if

the pressure exceeds 13 psi.

High Pressu re Relief Valve

Descaler

Boiler Pressu re Gauge

...................... Hangs below the water level inside the boi ler and is used to help cont r ol

.......... Indicates the amount of steam pressure in the boi ler.

Steam Header Assembly

....... A back-up mechanical device that opens to relieve steam pressure in

the boiler if the pressure exceeds 15 psi.

boiler surface scaling. Two descalers are used in each boiler.

......... Main steam supply line fr om the boiler to the steam header inlet in the

cooking control compar tment.

F24700 (October 2001)Page 11 of 68

VHX SERIES STE A M E RS - COMPONENT FUNCTION

COOKING COMPARTMENT CONTROLS

The upper section of the steam er c onsi sts of two separate cooking compartm ents. Each compartment functions independently wi th its own set of contr ols. Power is supplied to the controls only after the steam pressure rises above t he c ompartm ent pressure switch setting to close the N.O. contacts.

Ready Light (Green) Cooking Light (Red) Cooking Timer

Buzzer Door Switch

Steam Solenoid Valve

Compartment P r essure Switch

Manifold Pressure Gau ge

Steam Supply Manifold

....................... Signals end of a cook cycle, must be turned off manual ly.

................... Removes electrical power to the timer. If time is dialed on the cooking

............ When lit, indicates steamer is ready to cook.

............ When lit, indicates steamer is in a cooking cycle.

................. Use to set desired cooking cycle time between 0-60 minutes. When a

........... When energi zed, opens to allow steam into the cooking compartment

........ Indicates the amount of steam pressure in manifold. The intak e shut- off

.......... Main steam supply line fr om the boiler for eac h c ook ing compart ment.

tim er is set, the steam suppl y sol enoid valve is energized to al low steam into the cook ing compartment but only after the boiler has reached its operating pressure. Also, energizes the buzzer when time expires.

tim er and compartments are steaming, removes power to the steam solenoid valve when the compart ment door is opened.

(normally closed valve).

.... Supplies power to the controls only after the steam pressure ri ses above

approximately 3 psi to close the compartment pressure switch. The switch remains closed as long as steam pressure stays above this pressure.

valve should be adjusted so manifold pressure remains at 9 psi with both compartments on.

Supplies steam up to the steam sol enoid valve.

Intake Shut-Off Valve

........... Main steam supply shut-off from the boiler t o the steam supply manif old.

This valve should NOT be left fully O P E N to boiler steam supply. See

“INTAKE SHUT-OFF VALVE ADJUSTMENT (STEAM FLOW)" in “SERVICE PROCEDURES AND ADJUSTMENTS".

F24700 (October 2001) Page 12 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

REMOVAL AND REPLACEMENT OF PARTS

COMPONENT LOCATIONS

Cabinet Base Bo iler Contro ls

F24700 (October 2001)Page 13 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

Cabinet Base Bo iler Contro ls Contin ued

F24700 (October 2001) Page 14 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

Cooking Compartment Controls

WATER LEVEL CONTROLS

(MAIN OR AUXILIARY LLCO)

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

1. Open the cabinet base door.

2. Remove the cover from the pressure switch control box to access the water level controls. Refer to "CABINET BASE BOILER CONTROLS" under "COMPONENT LOCATIONS" in "REMOVAL AND REPLACEMENT OF PARTS".

3. Disconnect l ead wir es from the boar d being replaced.

4. Compress the lock ing tab on the board mounti ng "standoffs" and remove the water level control.

5. Reverse proc edur e to install and c hec k for proper operati on.

DISCONNECT THE ELECTRICAL

RELAY BOARD

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

1. Open the cabinet base door.

2. Remove the cover from the main control box to access the relay board. Refer to "CAB INET BASE BOILER CONTROLS" under "COMPONENT LOCATIONS" in "REMOVAL AND REPLACEMENT OF PARTS".

3. Disconnect all lead wires f r om the board.

4. Compress the lock ing tab on the board mounti ng "standoffs" and remove the relay board.

5. Reverse proc edur e to install and c hec k for proper operati on.

DISCONNECT THE ELECTRICAL

F24700 (October 2001)Page 15 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

WATER LEVEL GAUGE

ASSEMBLY

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

1. Open the cabinet base door and remove the right side panel.

2. Close the valve at the top and at the bottom of the gauge assembly.

3. Unscrew the packing nuts at t he top and bottom of the glass tube.

4. Slide t he glass tube upwards until the bottom of the tube is clear of the fitt ing and lift it out.

NOTE

damaged or broken.

NOTE:

gauge glass may break.

5. Install the tube using new sealing washers.

6. Open the top and bottom valves.

7. Turn the power switch ON and allow boiler t o come up to pressure.

8. Check gauge glass for water/steam leaks and i f necessary, graduall y tighten packing nuts until leak stops.

DISCONNECT THE ELECTRICAL

: Clean tube if dir ty or clogged and replace if

Do not ov er tighten the pack ing nuts or

PRESSURE SWITCHES

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

1. Open the cabinet base door and remove the left side panel.

2. Remove the cover from the pressure switch control box to access the pressure switches. Refer to "CABINET BASE BOILER CONTROLS" under "COMPONENT LOCATIONS" in "REMOVAL AND REPLACEMENT OF PARTS".

3. The pressure switches are located at the bottom of the box . The pressure switch on the left is the cycling the right is the high limit

4. If replacing: A. Cycling control - remove cov er from

DISCONNECT THE ELECTRICAL

or primary control ; the one on

control.

pressure switch and disconnect the lead wires.

1) Remove the mounti ng screws on the back side of the control box and lift out the pressure switch. Proc eed to step 5.

B. High li mit control - disconnec t the lead

wires.

5. Disconnect the pressure fittings at the bottom of the switc h.

6. Preset the new pressure switch to the approximate cut-out (OFF) and cut-in (O N) set points befor e installing. Refer to "PRESSURE SW ITCHES" in " S E RV ICE PROCEDURES AND ADJUSTMENTS".

7. Reverse proc edur e to install .

8. Adjust the pressure switch(s) final set points as outlined under "P RESSURE SWITCHES" in "SERVICE PROCEDURES AND ADJUSTMENTS".

BOILER ASSEMBLY

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

WARNING:

SERVICING THE UNIT.

WARNING:

DURING SERVI CING MUST BE CHECK E D FOR LEAKS. CHECK WITH A SOAP AND WATER SOLUTION (BUBBLES). DO NOT USE AN OPEN FLAME.

1. Blowdown the boiler and, if nec essary, allow to cool.

2. Disconnect the steam supply line, power leads and drain lines from the cooking compartment top to the boi ler base.

3. Refer to " HE A T EXCHANGER" and perform steps 3 through 12A.

4. Remove bolts securing the boiler t o frame.

5. Drain any remaining water from t he boiler. A. The suggested methods are:

DISCONNECT THE ELECTRICAL

SHUT OFF THE GAS BEFORE

ALL GAS JOINTS DISTURBED

1) Where the dr ain line exits the boiler on the lower left side, separate the drain line union.

2) Remove the access panel between the boiler and the cooking compartment on the right side.

3) Disconnect the steam supply hose from the cooking compartment steam manifold.

F24700 (October 2001) Page 16 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

a. From t he bottom right side, raise

the boiler two to three inches so it tilts to the left. When the remaining water has drained out, lower the boiler before. proceeding.

B. Remove the drain/ scale clean-out plug

from the bottom of the boiler.

6. Slide t he boiler forward and remove it from base frame.

7. Install a new boi ler and secure it t o frame.

8. Refer to " HE A T EXCHANGER" and perform steps 13 through 15.

9. Reconnect all steam, water, dr ain and power connections and check for proper operat ion.

BOILER FILL AND COLD WATER

CONDENSER SOLENOID VALVES

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

1. Turn off the water supply to the steamer.

2. Open the cabinet base door and remove the cover from the pressure switch control box to access the solenoid valves. Both solenoi d valves are l oc ated side by side at the r ear of the box with the boiler fill near the bottom and the cold water condenser near the middle. Refer to "CABINET BASE BOILER CONTROLS" under "COMPONENT LOCATIONS" in “REMOVAL AND REPLACEMENT OF PARTS”.

3. Disconnect the power l ead wir es from the solenoid valve being serviced.

4. Disconnect the water lines for the valve bei ng servi ced and remove the valve.

5. Reverse proc edur e to install .

DISCONNECT THE ELECTRICAL

PILOT G AS VALVE

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

WARNING:

SERVICING THE UNIT.

DISCONNECT THE ELECTRICAL

SHUT OFF THE GAS BEFORE

WARNING:

DURING SERVI CING MUST BE CHECK E D FOR LEAKS. CHECK WITH A SOAP AND WATER SOLUTION (BUBBLES). DO NOT USE AN OPEN FLAME.

NOTE:

servi ceable and should not be di sassembl ed. Once the problem has been isolated to t his component, replace it. Do not attempt to repair the assembly.

1. Open the cabinet door to access the Pilot gas valve.

2. Disconnect the lead wires.

3. Remove pilot gas tubing from the top of the valve (outlet side).

4. Remove the valve from the gas supply piping.

5. Reverse proc edur e to install and adjust pilot pressure as outlined under "G A S P ILOT PRESSURE ADJUSTMENT" in "SERVICE PROCEDURES AND ADJUSTMENTS".

ALL GAS JOINTS DISTURBED

Gas combination control valves are not

MAIN GAS VALVE

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

WARNING:

BEFORE SERVICING THE UNIT.

WARNING:

DURING SERVI CING MUST BE CHECK E D FOR LEAKS. CHECK WITH A SOAP AND WATER SOLUTION (BUBBLES). DO NOT USE AN OPEN FLAME.

NOTE:

servi ceable and should not be di sassembl ed. Once the problem has been isolated to t his component, replace it. Do not attempt to repair the assembly.

1. Open the cabinet base door to access the mai n gas valve.

2. Disconnect the lead wires.

3. Separate the uni on above the gas valve (outlet side).

4. Remove the valve from the gas supply piping.

5. Reverse proc edur e to install and adjust manifold pressure as outlined under "GAS MANIFOLD PRESSURE ADJUSTMENT" in "SERVICE PROCEDURES AND ADJUSTMENTS".

DISCONNECT THE ELECTRICAL

SHUT OFF THE GAS SUPPLY

ALL GAS JOINTS DISTURBED

Gas combination control valves are not

F24700 (October 2001)Page 17 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

BURNER HEAD ASSEMBLY

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

WARNING:

BEFORE SERVICING THE UNIT.

1. Remove the pressure gauge tubing and power cable f r om the rear of the control panel then remove the panel.

2. Disconnect the spark igniti on c able from the ignitor termi nal.

3. Disconnect pilot gas tubing from the air pressure switch tee.

4. Separate the uni on above the main gas v alve and remove the gas v alve piping assembly .

NOTE

assumes the use of a gas line quick connect or union at the gas supply inlet to the steamer.

5. Remove the screws from the burner head assembly end plate and pull the assembly out from the complete burner assembly .

DISCONNECT THE ELECTRICAL

SHUT OFF THE GAS SUPPLY

: Removal of the gas valve piping assembly

3. Remove the four nuts from the burner tube assembly then slowly out from the heat exchanger.

pull the assem bly straight

6. Reverse proc edur e to install and c hec k for proper operati on.

COMPLETE BURNER

ASSEMBLY

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

WARNING:

BEFORE SERVICING THE UNIT.

1. Refer to steps 1 thr ough 4 under "BURNER HEAD ASSEMBLY".

2. Remove the four nuts from c ombustion bl ower mounti ng flange and remove blower from burner tube assembly .

DISCONNECT THE ELECTRICAL

SHUT OFF THE GAS SUPPLY

CAUTION: Use care w hile removing as to no t damage the ceramic insulation surrounding the burner.

4. Reverse proc edur e to install and c hec k for proper operati on.

F24700 (October 2001) Page 18 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

HEAT EXCHANGER

WARNING:

SERVICING THE UNIT.

WARNING:

DURING SERVI CING MUST BE CHECK E D FOR LEAKS. CHECK WITH A SOAP AND WATER SOLUTION (BUBBLES). DO NOT USE AN OPEN FLAME.

1. Blowdown the boiler and, if nec essary, allow to cool.

2. Disconnect the electric al power to the machine at the main circuit box. Place a tag on the circuit box indicating the circui t is being serviced.

3. Remove the pressure gauge tubing and power cable f r om the rear of the control panel then remove the panel.

4. Disconnect the electric al lead wires exiting the boiler control box from:

SHUT OFF THE GAS BEFORE

ALL GAS JOINTS DISTURBED

NOTE

: Removal of the gas valve piping assembly assumes the use of a gas line quick connect or union at the gas supply inlet to the steamer.

8. Remove the four nuts from c ombustion bl ower

mounti ng flange and remove blower from burner tube assembly .

A. Auxiliary LLCO probe (Orange). B. Burner ground (green). C. Air pressure switch (yellow & yellow/white

stripe). D. Main gas valve (purple & grey). E. Pilot burner valve (red & grey). F. Spar k ignition cable.

5. Remove bolts securing the boiler control box (front ) to the base frame.

A. Lift up on left side of box and slide out.

6. Disconnect pilot gas tubing from the air pressure switch tee.

9. Remove the four bolts connecting the horizontal flue (left of boil er) to the flue "transition" piece.

A. Separate the horizontal flue f rom flue

"transition" piece, leaving the horizontal flue in place.

7. Separate the uni on above the main gas v alve and remove the gas v alve piping assembly .

10. Rem ove the four nuts fr om the com plete burner tube assembly then slowly assembly strai ght out from the heat exchanger.

CAUTION: Use care w hile removing as to no t damage the ceramic insulation surrounding the burner.

11. Rem ove the flue "tr ansi tion" piec e from the heat exchanger.

F24700 (October 2001)Page 19 of 68

pull the

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

12. For c learance of the heat exchanger only, remove the drain nut (petcock) and the lower adjustment knob from the water level gauge.

A. Remove the remaining bolt s on the heat

exchanger then pull heat exchanger straight out from the boiler.

13. To install heat exchanger: A. Clean the m ating surfaces on the heat

exchanger and boi ler.

B. Install a new gasket on t he boiler side of

the mounting fl ange.

F24700 (October 2001) Page 20 of 68

C. Insert the heat exchanger bac k into the

boiler and line up the mounting holes being careful not to disturb gasket.

D. At tach a 2" C-Clamp between the heat

exchanger mounting flange and the boiler side mounting flange. Tighten clamp only enough to allow start ing of bottom bolt into mounti ng hole.

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

: It may be necessary to use two clamps

NOTE

to draw the bottom of the heat exchanger cl ose enough to be clamped. Start one c lamp at a 3 o’clock position then instal l other clamp near the bottom. Once the bolts are tight enough, CClamp will fall away.

E. Install two bolts at the bott om and two

bolts at the t op on the heat exchanger flange and tighten the bolts a few turns at a tim e. Starti ng wi th the bottom bolts, tighten t he bolts in an alternating pattern between the bottom and top for a flush mounti ng of the heat exchanger flange and an even compression of the gasket.

NOTE:

hand, clean out the threads with the proper si z e tap.

F. O nc e those bolts are tight, install the two

If a bolt is not threading in properly by

bolts to the left and t he two bolts to the right on the heat exchanger flange. On the left side, be sure to install the rectangular flue gas pl ate then tight en the bolts in an alternating pattern.

15. Star ting at step 12, reverse procedure t o install the remaining components.

16. Check for water leaks and proper oper ation.

COOKING COMPARTMENT

DOOR(S)

Removal

1. Remove top cover.

2. Open the door.

3. Pull hinge rod up.

4. Reverse the procedure to install, m ak ing sure the door bushings are in place.

Gasket

1. Open the door.

14. To install flue "transition" pi ec e: A. Clean the m ating surfaces on the

"transition" piece and the heat exchanger face.

B. Install new gasket on t he " transition" piece

then secure to the heat exchanger using the remaining bolts.

2. Remove screws from t he gasket plate.

3. Pull t he gasket plate out from the door housing and remove the gasket.

4. Position the new gasket on the gasket plate and rever se t he pr oc edur e to install . Adjust the door as outlined in " DOOR SEALING ADJUSTMENT" under "COOKING COMPARTMENT".

NOTE:

this will compress the gasket excessively and interfere with proper door seal ing.

NOTE:

as nicks or cuts, will cause steam leakage.

Do not ov er tighten gasket plate screws as

Damage to the gasket sealing surface, such

F24700 (October 2001)Page 21 of 68

VHX SERIES STEAMERS - REMOVAL AND REPLACEMENT OF PARTS

Handle

1. Open the door.

2. Remove screws from t he top and bottom of the door.

3. Pull t he inner door panel out from the door housing with the gasket plate and gasket stil l attached.

NOTE:

diamet er fit s into the slot in the door and the latch lever must rest on t op of the handle latch screw.

5. Reverse proc edur e to install .

Latch Assembly

1. Open the door.

2. Remove screws from t he top and bottom of the

3. Pull t he inner door panel out from the door

4. Remove the screws from the side edge of the

When installing the spacers, the smaller

door.

housing with the gasket plate and gasket stil l attached.

door that secure the latch mec hanism and remove the lat c h from the door.

NOTE:

top of t he handle latch screw.

5. Reverse proc edur e to install .

4. Remove the nuts and spacers from the handle screws and remove the handle fr om the door.

F24700 (October 2001) Page 22 of 68

When installing, the lat ch lev er must rest on

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

SERVICE PROCEDURES AND ADJUSTMENTS

WARNING:

MEASUREMENTS WHILE POWER IS APPLIED TO THE MACHINE. EXERCISE EXTREME CAUTION AT ALL TIMES. IF TEST POI NT S ARE NOT EASI LY ACCESSIBLE, DISCONNECT POWER, ATTACH TEST EQUIPMENT AND REAPPLY POWER TO TEST .

Inspection

It is recommended the boiler be inspect ed for excessive lime scale build up in a time frame dependant on the quality of the local water suppl y and steamer usage. In har d water ar eas or for steamers heavily used, a frequent i nterval should be used. This inspection consists of an i nternal examination and cleaning of the boiler, an examination of the two hanging descaler s, and for lime build up on the water level probes. Also, a check of all boiler control s, including the pressure switches.

Periodic servi c e must be perfor med as outlined in these procedures. See “WATER CONDITIONING” under “GENERAL”.

Clean-Out

1. Turn power switch OFF . A. Boiler should automatically star t

2. Remove the burner assembl y and heat exchanger as outlined under "HEAT EXCHANGER" in "REMOVAL AND REPLACEMENT OF PARTS".

NOTE:

the hand hole cover is very limited on this model and is recommended to be rem oved for deliming purposes only.

3. Remove old descalers (cathodic protectors).

4. With a wire brush or equivalent: A. Dislodge and remove al l loose scale from

B. Remove all loose scale form the heat

C. Cl ean the mati ng surfaces of the heat

5. Check probe housing and water level pr obes for scale build up and cl ean as necessary. Refer to "WAT ER LEVEL CONTROLS TEST".

6. Check the drain line exiting the boiler for obstructions.

CERTAIN PROCEDURES IN THIS SECTION REQUIRES ELECTRICAL TEST OR

BOILER

blowdown/drain cycle.

Access to the int er ior of t he boiler through

boiler shel l. The loose material must be scooped from the boiler or flushed through the washout drain.

exchanger.

exchanger and boiler.

A. Remove the strainer clean out plug, turn

the steamer on and allow the boil er " fil l water" to f lush-out the drain line. Tur n the steamer off, remov e the cap and strainer screen and clean, if necessary, before replacing the screen and clean-out plug.

7. Inspect condition of t he descalers as outlined under "DESCALER (Cathodic Protec tor)" in t his section, and replace if necessary.

8. Install a new gasket and replace the burner assembly and heat exchanger by reversing the removal procedur e from step 2.

9. Delime the boiler as outlined under "DELIMING" in this section.

Deliming

Boiler deliming should be perf or med in a time f r ame dependant on the quality of the local water suppl y and steamer usage. In har d water ar eas or for steamers heavily used, a frequent i nterval should be used. See “W A TER CONDITI ONING” under “GENERAL”.

On steamers using a water t r eatment system , follow the instructions for t hat system to delime the boiler. Only use the type of chem ical recommended or described in t he instructions for deliming with t his type of system.

If a water t reatment system is not instructions for deliming the boiler as outlined in the steps below.

1. Turn power switch OFF . A. Boiler should automatically star t

blowdown/drain cycle.

2. Remove hand hole plat e and gasket (top front) from the boiler by removing the nut and clamp, then tap the cover lightly t o free it . Hold the stud in the plate while tappi ng to prevent the plate from droppi ng into boiler.

3. Clean the m ating surfac es of the hand hole opening and plate.

4. Delime the boiler : A. If t he boiler was delimed through a water

treatm ent system, proceed to step 7.

B. If t he boiler has not

proceed to step 5.

used, follow the

been delimed,

F24700 (October 2001)Page 23 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

WARNING

INSTRUCTI ONS FOR THE DE- LIMING CHEMI CA L BEING USED. USE PLASTIC OR RUBBER GLOVES TO AVOID SKIN CONTACT. IF T HE CHEMICAL COME S IN CONTACT WITH S K IN, RINSE WITH CLEAN WATE R.

5. Mix deliming solution ac c or ding to the

NOTE:

gallons.

NOTE:

steamer components, li ghtly rinse off with c lean water.

6. Install a new gasket on t he hand hole plate then

7. Ensure cooking compartment tim er s are O FF.

8. Turn power switch ON and open water supply

9. Allow the boiler to reach oper ating pressure

10. Steps 9A and 9B

11. Steamer is now ready for normal operation.

Descaler (Cathodic Protector)

Two descalers are installed inside the boiler shell and are used to as a preventative measure to:

• Reduce scale deposit buildup

• Help remove ex isting scale deposits

• Inhibit boiler and component corrosi on

The type of descaler used has a coiled wire (Cathode) wrapped around a solid c y lindric al core (Anode) that hangs by an open loop from the front horizontal support rod inside t he boiler.

: READ AND FOLLOW THE

instructions for the chemical being used.

Boiler water c apac ity is approximat ely seven

If deliming solution comes in contact with

A. Turn OFF water supply. B. Turn power switch ON to close the drain

valve.

C. Pour deliming solution into the boiler shell.

position and tighten the plate to the boiler.

valve.

and run for 90 minutes or per t he instructions for the deliming chemi cal in use.

A. Turn power switch OFF and allow the

boiler t o complet ely drain.

B. Turn power switch ON to refill boiler and

allow to heat until fully pr essuriz ed.

be repeated three times

must

to thoroughly rinse the boil er .

The descaler material s serve as a sacrificial "Anode" and "Cathode" c ombination that chem ically reacts with the contents of the boiler to meet the three object ives outlined above.

If t he c oiled wire has eroded away or if the cylindrical cor e of the descaler has eroded away to approximately half i ts original diameter, a new descaler should be installed. The si z e of a new descaler is approximat ely: 1 3/8" diameter and 3 3/4" long at the core.

NOTE:

decreases through erosion, the length of the descaler will increase. If the descaler has increased to a length t hat is touching the bottom of the boiler shell, the descaler should be replaced.

The descalers are accessibl e through the "heat exchanger" opening in the boi ler only. For removal of the heat exchanger refer to "HEAT EXCHANGER" under "REM OVAL AND REPLACEMENT OF PARTS".

To install a new descaler, stretch the coiled wire at the top to el ongate the wire and form an open loop. Hang the descaler on the front horizontal support rod so that its core will be completely below the minimum The descaler must not heat exchanger c ast ing.

While the di ameter of the descaler

water level in the boiler but hanging free.

contact the boiler shell or the

WATER LEVEL PROBE

HOUSING BLOWDOWN

The water contai ned in the probe housing, being under pressure, should be "blown through" this manual valve and be noti c eably v isible ex haust ing out the steamer drain. The pr obe housi ng blowdown should be perfor med in a time f r ame dependant on the quality of the local water supply and steamer usage. In hard water areas or f or steamers heavily

F24700 (October 2001) Page 24 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

used, a frequent interval should be used. This blowdown procedure is essential and component life by removing sedim ent and scalants that may be lodged in the probe housing.

NOTE:

pressures.

1. Remove the left side boiler base panel to

2. Turn the power switch ON and allow the boiler

WARNING:

HOT. USE CARE WHEN OPERATING, CLEANING OR SERVICING THE STEAMER. THE BOILER CONTAINS LIVE STEAM. STAY CLEAR WHEN OPENING THE VALVE.

3. Open the ball valve for approximately one

4. Close the ball val ve and repl ace left side panel.

5. Press the reset switch (manual) on the boiler

6. Steamer is now ready for use.

Boiler should be within normal operati ng

access the ball valve.

to reach operating pressure.

THE STEAMER AND ITS PARTS ARE

minut e whi le under pressure to thoroughly flush the probes and housing.

control panel and allow boiler to reach operating pressure.

to proper operation

WATER LEVEL CONTROLS

TEST

The procedure bel ow applies to the water level control boar ds for both the ol d and new styl e boiler controls. For additi onal inf or mation related to the new style control s, r efer to "RELA Y B OARD" and "SEQUENCE O F OPERATI ON" under "ELECTRICAL OPERATIO N". For specific infor mation related to the water level controls operation, refer to "WATER LEVEL CONTROLS" under "ELECTRICAL OPERATION".

Loose electri c al connections may prev ent the steamer from operat ing properly.

An accumulation of lime scale on or near the water level sensing probes may cause them to retain water (moi st) on the probe surface and gi ve a false reading. Also, a cracked or damaged insulator may give a false reading.

These conditions may cause one or more of the following to occur:

• Gas burner no igni tion

• Boiler no fill

• Boiler overfill.

• Boiler no fill and dry fire

: Dry f iring m ay cause damage to the heat

NOTE

exchanger, burner assembly or the boiler. I f this conditi on is suspect, the affected components

should be inspected.

WARNING:

POW E R TO BE APPLIED TO THE UNI T DURING THE TEST. USE EXTREME CAUTION AT ALL TIMES.

Main Water Level Control NOTE:

functioning control that provides f or low level cut-off protecti on and differential water level control

1. Turn power switch ON and verify: A. Low water light is illuminated (front control

B. HL LED is illuminated on the water level

C. Boiler is filling with water.

2. At the end of the initial fill: A. Verify approxi mately one inch of water

B. Verify "green" ready light in the reset

THE FOLLOWI NG ST EPS REQUIRE

The mai n water level control is a dual

panel).

control boar d.

1) If boiler isn’t filling with water: a. Verify 120 Volt AC is being

applied to the fill valve. b. Verify fill valve isn’t clogged. c. Ver ify 120 Volt AC is on main

water level control board.

2) I f water level cont rol board doesn’t have 120 Volt AC:

a. Check it’s power source at the

10 pin J3 connector, pin 1 (white) and pin 2 ( black). Disconnect the 10-pin J3 connector from the r elay board in the m ain boiler c ontrol box.

b. If no volt age is measured on J3

pins 1and 2, check t he F1 fuse (resettable c ircuit br eak er ) in the main control box, and the power switch connecti ons i n the power switch box.

c. I f 120 volt AC was measured on

J3 connector pins 1 and 2 but not on the water level control board, verif y wi r e c onnec tions. There should be continuity between L1 on the water level control boar d and J 3 pin 7. There should also be cont inuity between L2 on the water level control boar d and J 3 pin 6. This path incl udes connec tions thru the J1 connector.

visible in t he boiler sight glass.

switch is illuminated.

F24700 (October 2001)Page 25 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

C. Verify LED’s on the water level control

board, HL LED should be off, and LLCO LED should be illuminated.

3. Open the ball valve in the probe housing assembly (boi ler left side) about hal f way, to gradually remove boiler water and ac tivate a fill cycle.

Do not

the ignition cycle.

press the reset sw itch to start

The next step requires a visual sight glass measurement that cannot be obtained, if there is boili ng ac tion in the vessel.

A. Verify water level in the boiler sight glass

drops 1/4" to 3/8" before a fill cycle is initiated. Repeat at least twice to verify correct fill.

1) I f proper fill wasn’t obtained: a. Verify probes 50, 51, and 52

have t he c or rect colored wir e to them and to the water level control boar d.

b. Remove the 3 probe assembly ,

clean lime scale build-up f r om the probes and compare pr obe lengths to drawing.

C. Repeat at least twice to veri fy correct

LLCO operation.

Auxiliary Low level Cut-Off Co ntrol

5. Conti nued testing with focus on the auxiliary LLCO circuit. With water below the lowest visible level in the sight glass (bel ow Aux LLCO probe), and boiler in state of initial fill:

A. Verify Aux LLCO LE D is off on the Aux

water level control board.

B. Verify Low Water light is illuminated (front

control panel).

C. Verify 24 volt A C is on Aux LLCO COM,

and 0 volt is on Aux LLCO N.O. contacts.

1) With the water level above the Aux LLCO probe and in the initi al fill state:

a. Verify Aux LLCO LE D is

illuminated on the auxiliary low water board.

b. Verify N2 on the relay board is

illuminated (new style boiler controls onl y ) .

c. Ver ify t he "green" ready light in

the reset switch is illuminated.

c. Remove 3/8” flex line from t he

probe housing assembly t o the boiler and r emove any obstructions. The 1/4" compression fitting elbow and 1/4" tee i nto the boiler shel l for the balance tube ar e sloped 1/8" so condensation drains into boiler. When replacing, t he assembly

have t his slope

must

to prevent a blockage from condensate build- up.

4. Test the water level c ontrol board LLCO circuit. A. With the boiler full with water, turn off the

water supply and open the ball valve in the probe housing assembly.

B. Shortly after the water dr ops bel ow the

lowest visible level in the sight gl ass, the LLCO LED on the water level c ontrol board should turn off, LLCO relay should de-energize and t he nor mally open contacts should ret ur n there shelf stat e.

d. Verify 24 volt AC is on the Aux

LLCO common and normal ly open contacts of the auxiliary water level control board.

2) With the mai n gas valve turned off, water supply valve turned off, and probe housing assembly ball valve opened, press the reset switch.

a. Verify low water light (front

control panel). b. Blower comes on. c. Gas pilot cycles at

approximately 15 seconds on

and 5 seconds off.

3) Shor tly af ter water level drops below the lowest visible level in the sight glass, the Aux LLCO circui t should be activated.

a. Low water light tur ns on. b. Aux LLCO led turns off. c. Combustion blower i s de-

energized.

d. Gas pilot st ops cyc ling.

4) Press reset switch to verify lo ckout.

5) Disconnect lead wire from Aux LLCO probe. If there is any measurable resistance between the probe and the

F24700 (October 2001) Page 26 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

boiler shel l, remove and cl ean the Aux LLCO probe.

a. Replace the probe and check

resistance again. If resistance is still present, install a new probe.

b. Replace lead wir e on pr obe and

repeat steps "2) thru 4)" to verify proper operati on.

PRESSURE SWITCHES

WARNING:

POW E R TO BE APPLIED TO THE UNI T DURING THE TEST. USE EXTREME CAUTION AT ALL TIMES.

Remove the cover from the pressure switch control box to access the t wo pressure switches. The pressure switch near the front is the cycling switch and the one beside it is the high l imit pressu re switch.

Cycling

1. If t he boiler is already operating, proceed to step 2. If the boiler is not start the boiler as outli ned under " CA B INET BASE BOILER" in "STEAMER OPERATION".

2. Turn one of the cooking compartment tim er s ON to exhaust st eam from the boiler.

3. Monitor the boiler pressure gauge for several cycles and note the pressures at which the burner comes ON and goes OFF.

A. The mai n burner should come O N at 8 PSI

THE FOLLOWI NG ST EPS REQUIRE

pressure

already operat ing,

and go OFF at 10 P S I. If the readings differ, adj ust the pressure settings as described below.

1) T wo pressure adjustment screws extend thr ough the top of t he swit c h case. The screw directly abov e the

side pointer r aises or lowers both

right the cut-out ( OFF) and the cut-in (ON) set points sim ultaneously, wit hout affecting the differential.

The screw directly above the left pointer raises or lowers the cut-in (ON) set point and changes the differential.

2) T ur n the adjustment screw above the

side pointer to obtain the proper

right cut-out (OFF) setting fir st, then adjust the other screw to obtain the proper cut-in (ON) setting.

a. A clockwise

the pressure setting whil e a counterclockwise decreases the pressure setting.

rotation increases

rotation

side

4. The cycling pressure switch will maintain the steam pressure setting in the boil er by c y c ling the mai n burner ON and OFF .

High Limit

Adjusting t he High Limit pressure switch fr om a cold startup is the preferred condi tion of the boiler. On the initial cold startup, the highest over shoot pressure (drift) is achiev ed aft er the burner cycles OFF for the f irst time. If the boiler is already operating, the pressure setting can still be made after foll owing the procedures outlined below.

1. The high limit pressure switch should be adjusted to allow a maximum pr essure in the boiler of 14.5 to 15.0 P S I. Befor e making adjustment s t o the high li mit pressure setting, the 13 PSI pressure rel ief valve (PRV- l eft side) must be high enough pressure in the boiler to properly set the switch.

A. The suggested methods to prevent t he

2. Turn the power switch ON and allow the boiler to completely fill.

A. High Pressure and Low Water indicator

3. When water in the boiler reaches the minimum level, the green light on the r eset switc h will come ON.

A. Press the reset switch on the front control

4. Monitor the boiler pressure gauge and note t he pressure at which the high limit switch opens.

NOTE

: In f r ont of the boiler there is an additional

temporarily

valve from releasing pressure are:

1) Use a wooden block, a hand tool or other object to hold the valve plunger down.

2) Use a m etal wire threaded through the hole in the valve handle and tie the pressure relief valve handle to the piping bel ow i t.

3) I f neither of the two methods keep the valve fully c losed without leaks, an alternate method is:

a. Turn the power switch OF F and

b. Remove the discharge piping

lights (amber) com e ON.

panel to reset the High Pressure and Low Water safety controls.

1) I gnition sequence start s, main burner lights and water in the boiler begins to heat.

disabled. This will allow a

allow the boi ler to blowdown.

from the v alve outlet and insert a pipe plug for only.

temporary

use

F24700 (October 2001)Page 27 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

Mechanical Pressure relief valve factory set to approximately 15 P SI. If the pressure in the boi ler reaches this level, the valve will OPEN.

A. High pressure light (amber) will come ON.

1) I f the pressure switch opens at a pressure range other than 14.5 t o

15.0 PSI then an adjustment t o the switch setting should be made.

a. Proceed to step 5.

CAUTION: While making the adjustment, do not press on the wheel wi th extreme force. The switch may ro tate and devel op a leak at the compression fittings or in some cases, the rear lead wire may t ouch the control b ox and create an electrical short.

5. Turn the adjust ment wheel sev er al clic k s to change the pressure switch set point.

A. A counterclockwise

pressure switch set point while a clockwise switch set point.

NOTE:

during rotation, the pressure setting is changed approximately 1/8 PSI.

in small increments.

6. Raise the handle on the 15 PSI mechanical pressure relief valve and open the val ve for approximately 4 minutes. This will exhaust steam down the drain line and lower the boiler pressure.

A. High li mit pressure switch closes at

B. Lower the boiler pr essure to approxim ately

C. Ignition sequence starts, main burner

7. Repeat steps 4 through 6 until the High Li mit Pressure Switch opens at the corr ec t pressure.

8. If t he 13 P S I pressure relief valve (P RV - left side) was temporari ly disabled as outl ined in step 1:

A. Turn the power switch OF F and allow the

B. Return the valve to it s original stat e.

9. Check steamer for proper operat ion.

For every click of the adjustment wheel

approximately 12 PSI (non-adjustable).

1) Press the reset switch to reset the

8 PSI.

lights and water in the boiler begins to heat.

boiler t o blowdown.

rotation raises the pressure

High Pressure safety c ontrol. a. High pressure light (amber) goes

out.

rotation lowers the

Make the adj ustment

FILL A ND COLD WATER

SOLENOID VALVES

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

1. Check to ensure the solenoid valve is receiving power.

A. If t he sol enoid valve is receiving power but

B. If t he sol enoid valve is receiving power

2. To check solenoid valve further, pr oc eed to step 3 through 8 for disassembly and inspect ion of internal com ponents.

3. Shut water supply off, disconnect the water line from the v alve body then remove the solenoid valve from t he steamer.

4. Remove the coil assembly from the valve stem by lifting up on t he retaining c ap at the top of the solenoid valve and sliding the metal cov er plate off.

5. Clamp t he body of the valve in a vise.

6. Mark a scribe line on the stem nut to the valve body for proper re-tight ening.

7. Remove the stem locking nut t o remove the stem f rom the valve body.

8. All parts are now accessible for inspection and cleaning.

NOTE:

damaged or worn, then r eplace the solenoid valve. Do not reuse damaged or worn parts.

solenoid parts are avail able as a service replacement.

A. Check rubber seal on bottom of plunger. B. Check plunger spri ng. C. Check O-ring in valve body.

DISCONNECT THE ELECTRICAL

the v alve is not opening, the c oil may be malfunctioning.

1) Remove the lead wires from the solenoid coi l and check f or c ontinuity .

a. If continuity is measured,

proceed to step "1. B .".

b. If no continuity is measured,

replace the sol enoid valve and check for proper operation.

and the v alve appear s to be opening but little or no water is flowing through it, then the v alve por ts may be clogged with debris or a valve c omponent malfunct ioning.

If internal solenoid parts appear to be

No internal

F24700 (October 2001) Page 28 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

D. Check por ts in valve body .

9. Reverse proc edur e to install .

BOILER BLOWDOWN/DRAIN

SOLENOID VALVE

The water contai ned in the boil er , being under pressure, should be "blown through" this valve and be noticeabl y vi sible exhausting out the steamer drain. Dai ly boil er blowdown is essential operation and component life by removing sediment and scalants that may be lodged in the chamber of the boiler .

The boiler blowdown/drain process is an automatic function and should start whenever the power switch is turned OFF after a normal operating cycle. The blowdown solenoid is a normally open (N.O.) valve that CLOSES when energized by the power switch. When the power switch is turned OFF, the blowdown solenoid is de-energiz ed and the valve OPENS to allow the boil er to blowdown.

If t he blowdown operation appears to func tion sluggishly or not at all, considerable scalants may be lodged in the dr ain line plumbing exiting the boiler, st r ainer, and/or t he blowdown valve.

1. Turn the power switch OF F and allow boil er to blowdown.

2. Turn the ON/OFF knob on t he main gas valve to OFF.

3. Remove the strainer clean-out pl ug located in the center of cap.

4. Turn the power switch ON and allow the boiler "fill water" to flush-out the drain line until no debris is seen exi ting the cl ean- out hole.

5. Turn the power switch and the water supply OFF.

to proper

A. If t he boiler blowdown is ok, t hen the drain

line and valve are clear of debris and the valve is functi oning properly.

B. If consi derable li me scale debris i s

apparent, then not only the blowdown valve, but also the boil er and water level probes must be thoroughly cleaned. See "FILL AND COLD WAT E R S OLENOID VALVES" for an inspection and cleaning procedure of a solenoid valv e and "BOILER" for a procedure on boiler inspection, clean-out and deliming.

INLINE WATER STRAINER

CLEANING

The procedure outlined below can be used to inspect and cl ean the inli ne water str ainer for the blowdown solenoid v alve and, if installed, the inli ne water strainer for the boiler fill solenoid valve. I nline Y strainers should al ways be located upstream of a water solenoid valve.

NOTE:

installed so the water flow is di r ec ted towards the solenoid valve and the leg of the Y with a thr eaded cap is pointing downwards to catch debris.

1. Turn the power switch OF F to and allow the

2. When blowdown completes, shut OFF the

3. Remove the cap and strainer screen from the

4. Remove the screen fr om the cap and clean any

NOTE:

replace it with a new one.

5. Insert screen int o c ap then re-install cap to

6. Turn the water supply and power switch O N

7. Turn the power switch OF F and check strainer

For proper operat ion, the strai ner must be

boiler t o blowdown.

water supply.

leg of the Y pointi ng downwards toward the floor.

accumul ated debris fr om the screen and also remove any debris tr apped in the opening of the strainer body .

If screen can not be thoroughly c leaned,

strainer body.

and allow the boi ler to reach operat ing pressure.

for l eak s, as the boiler blows down.

6. Turn the ON/OFF knob on t he main gas valve back to ON.

7. Remove and clean the strainer as outli ned under "INLINE WATE R S TRAINER CLEANING".

F24700 (October 2001)Page 29 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

MAIN BURNER IGNITION

CHECKS

The complete gas burner assembly is located inside the heat exc hanger casting in the boiler. T he perforat ed burner head funct ions as both pilot and main gas burner. The inner port ion of the per forated burner head serv es as the pi lot to light the m ain burner during t he trial for igni tion. Once the main burner li ghts, the flame encom passes the enti r e perforat ed burner head and the pil ot flame extinguishes.

If burner ignition problems are encountered, perf or m the following checks to ensure components are adjusted properl y .

1. Turn power switch ON and allow the boiler t o fill.

2. Verify "low water" and "hi gh pr essure" saf ety circuits are satisfied.

A. Water Level in boiler.

1) Appr oxim ately one visible inch of water in the sight glass.

2) Auxiliary LLCO is satisfied.

b. LED on auxiliary water level

B. High Limit Pressure Switch

1) Z er o reading on boil er pr essure gauge.

NOTE:

equal to 8 PSI and OFF at 10 PSI.

NOTE:

automatically resets at approximately 12 PSI.

C. Press the reset switch to reset the safety

circuits.

NOTE:

front c ontrol panel shoul d be OFF.

3. Verify blower is running and its operation is quiet.

4. Verify air pressure switch is CLOS E D.

Hi Pressure and low water li ghts on

1) safety circuit satisfied).

NOTE:

indicat e bearing wear and reduce air pressure output.

N12

on relay board O N ( 120V A C suppl ied

to the blower).

on relay board O N ( low water

safety circuit satisfied).

board ON.

Burner cycles ON at less than or

High Limit Pressure Switc h

on relay board O N ( high pressure

A "noisy" bl ower rot ation may

N13

B. Pilot gas valve energized and ignition

NOTE:

not switch setting as outlined under "AIR PRESSURE SWITCH ADJUSTMENT".

5. Verify 24VAC to ignition module and pilot valve.

6. Verify spark and pilot ignition. A. If pilot lights, proceed to step 7. B. If sparking occurs but pilot does not

C. If spark is not

on relay board O N ( air pressure

switch CLOSED and condition satisfied).

sequence starts.

If N13 is not

energized, t hen check the air pr essure

on relay board O N ( 24V A C is being

supplied f or the system).

N13

on relay board O N ( 24V A C is being

supplied to the ignition module).

N14 & N15

being supplied to the pilot ignition timing circuit and the pilot valve.

then check the pilot pressure setti ng as outlined under "GAS PILOT PRESSURE ADJUSTMENT".

1) Restart power ON sequence by "rapidl y " turning the power switch OFF then bac k ON. A rapi d switc hing is needed to keep the boiler from starting automatic blowdown.

2) Remove igniti on c able boot fr om the ignitor rod terminal and check i gnitor position in the burner head assembly.

3) Measure distance the ignitor terminal extends past the i gnitor nut. Distance should measure approximat ely 3/4" to 7/8". See diagram 5898 "COM P LE TE BURNER ASSEMBLY" at the end of this procedure.

NOTE:

and not the ceramic insul ator. a. If distance is ok, proceed to step

b. If distance is other than stated,

c. Re-c onnect ignition cable.

4) Pr ess reset switch t o star t the ignition process.

ON or Pilot gas valve is

on relay board O N ( 24V A C is

occurring:

Touch igni tor term inal only

5) below and perfor m step "a" and "b" then continue with step "6)".

loosen ignitor nut, set the ignitor position and then re-tighten the ignitor nut.

light,

F24700 (October 2001) Page 30 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

a. If ignitor sparks and pilot li ghts,

proceed to step 7.

b. If ignitor does not spark, pr oc eed

to step "5)" bel ow.

5) Restart power ON sequence by "rapidl y " turning the power switch OFF then bac k ON. A rapi d switc hing is needed to keep the boiler from starting automatic blowdown.

a. Grasp the ignitor terminal and

rotate the ignitor approxim ately 45°.

b. Re-connect ignition cable.

6) Press the reset switch to start the ignition process.

a. If ignitor sparks and pilot li ghts,

proceed to step 7.

b. If ignitor does not spark, r epeat

steps "5)" through this step until rod has been rotated 360°.

7. Verify main burner ignit ion. A. If main burner l ights and remains lit with

no intermittent problems, t hen bur ner is functioning properly.

B. If main burner does not

light or shows intermittent problems, t hen c hec k the main burner pressure setting as outl ined under "GAS MANIFOLD PRESSURE ADJUSTMENT".

1) I f pressure is ok but i ntermittent

burner problems continue, t hen the following components must be examined.

2) T ur n the power switch OFF and al low

the boiler to blowdown.

WARNING:

DISCONNECT THE ELECTRICAL POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

Verify the burner tube insulation and heat exchanger c ast ing are intact.

NOTE:

The suggested method for inspection is to mount a sm all mirror to a 2 foot long rod and insert t he mirror inside the burner tube and use a flashlight to illuminate the area.

NOTE:

If necessary, the complete burner tube assembly c an be removed to aid in performing the measurement and inspections.

a. Inspect the ceramic i nsul ation for

damage at the ar ea around the burner head inside t he bur ner tube.

b. Measure ceramic insulation

insertion depth/location from the end of the insulation that surrounds the burner head to the opposite end of the burner tube (end plate mounting flange). The dimension should measure approximately 23 5/8 inches ±1/8. See diagram 5898 "COMPLETE B URNE R ASSEMBLY" at the end of this procedure.

c. Ver ify t hat casting debri s i s not

clogging t he "heat transfer fins" at the end of heat exchanger casting and that the fins have not eroded away.

d. Inspect the interior of heat

exchanger casting for signs of water leakage. Also, signs of water leakage into the heat exchanger casting may be determined by exam ining the bottom ar ea of the flue transit ion piece and f loor.

WARNING:

SHUT OFF THE GAS BEFORE

SERVICING THE UNIT.

3) Remove bur ner head assem bly as outlined under "BURNER HEAD ASSEMBLY" in "REMOVAL AND REPLACEMENT OF PARTS".

4) T he c omplete or interm ittent loss of burner igni tion or a burner operat ion that is loud and noisy may i ndicate the burner tube insulation or heat exchanger casting is damaged.

F24700 (October 2001)Page 31 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

F24700 (October 2001) Page 32 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

AIR PRESSURE SWITCH

ADJUSTMENT

The air pressure switch senses the pressure level produced by the blower for combustion. When the pressure is sufficient, the switch closes and supplies power to the igni tion control module. The gas ignition sequence starts to light the gas pilot and then mai n burner. If the gas pilot is not lighting (valve not energized), the ignition control module may not be receiv ing power, assuming the minimum water level is satisfied. Check the air pressure switch operation then adjust if necessary as outlined in the procedur e below.

1. Turn the power switch OF F.

2. Remove the left side panel from t he c abinet base.

A. Inspect the air intake to the blower for

debris buil d up and c logging.

A. Turn the adjust ment screw ful ly clockwise

to the highest setting.

1) I f debris is found, clean it away from the air i ntake.

B. Turn the power switch ON and verify main

burner igni tion.

1) I f burner ignites then no adjustment to the pressure switch setting is necessary.

2) I f burner does not step 3.

ignite, proceed to

B. Slowly tur n the adjustment screw

counterclockwise energizes then add ½ turn to the adjustment.

NOTE

: The screw head should not

past the screw housing.

1) I f Pilot gas valve energizes, proceed to step 5.

2) I f Pilot gas valve does not check the following:

a. Remove the lead wires from the

switch and v er ify wit h a meter that the switch c ontacts are closing with the blower ON. If necessary, continue to turn the adjustment scr ew several turns counterclockwise switch contacts.

b. If t he swit c h c ontacts are not

closing, turn the power switch OFF, r emov e the pressure switch from the TEE and c hec k the air orifice for debris build up and clogging. If debri s is found, clean it away from t he or ifi c e.

until the pilot gas valve

extend out

energize,

to CLOSE the

3. Open the cabinet base door and turn the ON/OFF knob for t he main gas valve to OFF.

4. Adjust the air pressure switch setting as follows:

F24700 (October 2001)Page 33 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

2) Press the reset switch to start the ignition process.

C. Li sten for main gas burner ignit ion to

verify operation.

GAS PILOT PRESSURE

ADJUSTMENT

c. Replace the orifice, pr essure

switch and connect the lead wires to the switch. Turn the power switch ON and adjust the pressure switch again as outli ned in steps 4A and 4B. Verify t he pilot gas valve is energizing.

d. If t he pilot gas valve is not

energizing and power is available to the pressure switch, turn the power switch OF F. Replace with a new air pr essure switch and adjust the switch as outlined from step 3 thru the end of this procedure.

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

WARNING:

SERVICING THE UNIT.

1. Open the cabinet base door to access pilot gas valve.

2. Remove the pil ot pressure plug tap f r om the outlet

DISCONNECT THE ELECTRICAL

SHUT OFF THE GAS BEFORE

side of valve.

5. Restart the ignition sequence by "r apidly" turning the power switch OFF then back ON. A rapid switchi ng is needed to keep the boiler from starting automatic blowdown.

A. Press the reset switch to start the ignition

process.

1) Listen for gas pilot ignition to verify operation.

a. If gas pilot igni tion is successful ,

turn the ON/ OFF knob for the main gas valve back to ON.

b. Listen for main gas burner

ignition to verif y operation.

B. Verify the pil ot and main bur ner both ignite

in su ccession.

1) Restart the ignition sequence by "rapidl y " turning the power switch OFF then bac k ON. A rapi d switc hing is needed to keep the boiler from starting automatic blowdown.

F24700 (October 2001) Page 34 of 68

3. Turn the gas supply and power switch ON.

A. Install a hose barb adaptor and attach a

gas pressure manometer.

A. Once the boiler fills, press the reset switch

to start the ignition process.

NOTE

: The reset switch can be pr essed af ter the green ready l ight on the switch comes ON. This indicates the water level in the boiler is at the mi nimum operating level.

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

4. After the main burner lights, allow the boil er to reach operati ng pr essure then t ur n the ON/OFF knob for t he main gas valve to OFF.

5. Restart the ignition sequence by "r apidly" turning the power switch OFF then back ON. A rapid switchi ng is needed to keep the boiler from starting automatic blowdown.

A. Press the reset switch to start the ignition

process.

6. After the pilot bur ner lights, c ompare the manometer pressure reading to the pr essure chart near the end of this procedur e.

NOTE:

The pilot gas valve operates on a time delay circuit and will only be energized for approximat ely 15 seconds to light the main burner then shut OFF. The pilot pressure reading must be t ak en while the pilot valve is energized within t his time interval. After the main burner ignition time expires, the ignition control module will sense there is no flame present and will then try to re-establ ish a flame to light the main burner. This cycle will continue to repeat until the main gas valve is turned back ON.

A. If t he pr essure i s not

correct, pr oc eed to

step 7 to adjust.

B. If t he pr essure i s corr ec t, turn the power

switch OFF, replace the adjustment screw cap and pilot pressure plug tap to the gas valve. Turn the knob on the main gas valv e back to ON.

7. Remove the adjustment screw cap to access

the pressure adjustment screw.

8. With the burner lit, set the pressure as outlined below.

A. To increase pressure, tur n the screw

clockwise

B. To decrease pressure, turn the screw

NOTE:

counterclockwise

Accurate gas pressure adjustments can only

be made with the gas O N and the burner lit.

PRESSURE READINGS (INCHES W.C.)

GAS TYPE

Natural

Propane

NOTE:

If t he incomi ng line pressure is less

PILOT

MANIFOLD

RECOMMENDED

3.5 7.0

3.5 11.0

LINE

MINIMUM

MAX

14.0

than the minimum recomm ended, then the manifold pressure can not be set correctly.

9. Once the corr ec t pressure has been set, turn

the gas supply and power switch OFF. Replace the adjustm ent screw cap and pilot pressure plug tap on the valve.

10. Turn the knob on the main gas valve to O N,

the gas supply ON and check for proper operation.

F24700 (October 2001)Page 35 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

GAS MANIFOLD PRESSURE

ADJUSTMENT

WARNING:

POWER TO T HE MACHINE AT THE MAIN CIRCUIT BO X. P LA CE A TAG ON THE CI RCUIT BOX INDICATING THE CIRCUIT IS BEING SERVICED.

WARNING:

BEFORE SERVICING THE UNIT.

1. Open the cabinet base door to access main gas valve.

2. Remove the manifold pr essure tap plug from the outlet

DISCONNECT THE ELECTRICAL

SHUT OFF THE GAS SUPPLY

side of valve.

A. If ot her appliances are connect ed to the

same gas line, turn them all ON and check manometer pressure reading again. If the pressure drops ½ inch water column or more, t hen the gas supply needs to be checked by the gas line installer or the local gas company for adequate sizing.

NOTE:

The gas supply li ne to the steamer should be a minimum of one inch diameter (ID).

B. If t he pr essure does not drop as described

above but the manifold pressure still requires adjustment, proceed t o step 5.

5. Remove the adjustment screw cap to access the pressure adjustment screw.

A. Install a hose barb adaptor and attach a

gas pressure manometer.

3. Turn the gas supply and power switch ON. A. Once the boiler fills, press the reset switch

to start the ignition process.

NOTE:

The reset switch can be pressed after the green ready l ight on the switch comes ON. This indicates the water level in the boiler is at the mi nimum operating level.

4. After the main burner lights, allow the boil er to reach operati ng pr essure then compare the gas manometer pressure reading to the pr essure chart near the end of this procedur e.

6. With the burner lit, set the pressure as outlined below.

A. To increase pressure, tur n the screw

clockwise

B. To decrease pressure, turn the screw

NOTE:

counterclockwise

Accurate gas pressure adjustments can only

be made with the gas O N and the burner lit.

PRESSURE READINGS (INCHES W.C.)

GAS TYPE

Natural

Propane

NOTE:

If t he incomi ng line pressure is less

BURNER

MANIFOLD

RECOMMENDED

3.0 7.0

3.0 11.0

LINE

MINIMUM

MAX

14.0

than the minimum stated, then the manifold pressure can not be set correctly.

F24700 (October 2001) Page 36 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

7. Once the corr ec t pressure has been set, turn the gas supply and power switch OFF. Replace the adjustm ent screw cap and manifold pressure plug tap plug on t he valve.

8. Turn the gas supply on and check for proper operation.

IGNITION CONTROL MODULE

CHECKS

1. Turn the power switch ON and allow the boiler to fill.

2. Aux. water level control satisfied and high limit closed.

3. Press the reset switch. A. Combustion blower comes on and

generates pressure to close the ai r pressure switch contacts.

B. Ignition control module is energized and

trial for ignition starts. Chec k for 24VAC between terminals fi ve and six.

C. Ignition module closes the internal pilot

valve contacts. Check for 24 volts between terminals two and three.

F. " Rapidly", turn the power switch OFF then

ON. A rapid switching is needed to keep the boiler from st ar ting autom atic blowdown. Then press the reset button.

NOTE:

module continues sparking for a total of 90 seconds, then locks out. The module remains locked out unt il the power switch i s tur ned to OFF then bac k ON and the reset switch i s pressed to re-start the ignition trial cycle.

If t he power is not re-set, the i gnition

1) High voltage is sent fr om term inal nine to the spark electrode and sparking begins.

2) At the same time, pilot timing circuit (control boar d) and pilot valve are both energized allowing gas flow to the pilot.

NOTE:

by the relay board tim er c ircuit for approximately 15 seconds to light the main burner.

D. Pilot ignition i s establ ished (pilot lit), and

main gas valve is energiz ed. Check for 24 volts between terminals one and two.

1) Spar k ing stops.

2) I gnition module monitors mai n bur ner

3) After 15 seconds relay boar d timer

E. As long as the igni tion control module is

sensing a burner flame through t he igniti on cable on terminal nine, the internal main voltage (MV) and pilot (PV) c ontacts (N.O.) remain closed.

The pilot valve will be energized

flame.

tim es out. a. Pilot valve de-energized.

Terminals:

1. Main Valve #1 with the f lame sensing elec trode sensing an adequate burner f ame. This output voltage will remain present as long as the burner flame remains adequat e.

2. MV/PV (c ommon).

3. Pilot Valve #3 at the instant an input voltage is supplied to the modul e. This output volt age will remain present on term inal #3 providing an adequate pilot flame is established within 90 seconds. In the ev ent that an adequate pi lot flame is not established within 90 seconds this output voltage will drop out.

4. Ground (burner).

5. 24VAC Neutral (ground).

6. 24VAC Input.

7. High Volt age to spark electrode. Prov ides high output voltage (13kv peak) t o the spark electrode t o light the gas pilot. O nc e pilot i s l it, provides a path for flam e c urrent sensing by the Ignit ion Module via the spark electrode high voltage cable on ter minal #9.

- 24VAC will be present on terminal

NOTE:

seconds, you can re-start t he igniti on sequence.

If pilot flame is not sensed within 15

F24700 (October 2001)Page 37 of 68

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

Spark Verifi cat ion T est

1. Turn the power switch OF F.

2. Check to ensure that all electrical terminal connections on the igniti on c ontrol module and the ignitor rod are clean and tight. I f the ignition cable appears to be damaged, replace it and re-try lighting bur ner .

3. Verify that the ignition c ontrol m odule and the burner ground have a good ground connecti on.

A. If loose connections are found, make t he

necessary adjustment s and check for proper operati on.

B. If connec tions are ok but sparki ng does

not occur, pr oc eed to step 4.

4. Remove ignit ion cable boot from t he ignitor r od terminal and check ignitor posit ion in the burner head assembly.

A. Measure distance ignitor terminal extends

past ignitor nut, approx imately 3/4" to 7/8" . See diagram 5898 "COMPLETE B URNE R ASSEMBLY" under "MAIN BURNER IGNITION CHECKS”.

NOTE:

Touch igni tor term inal only and not

the ceramic insulator.

1) I f distance is ok, proceed to step 5 and perform steps B thru E.

2) I f distance is other than stated, loosen ignitor nut, set the ignitor position.

3) Re-c onnec t ignition cable.

B. Turn the power switch ON and allow the

boiler to fill.

C. Press reset switch to start the ignition

process.

1) I f pil ot lights, then ignition system is working properly .

2) I f igni tor does not spark, proceed to step 5.

5. Turn the power switch OF F.

1) I f pil ot lights, then ignition system is working properly .

2) I f igni tor does not spark, repeat steps E thru thi s step unt il rod has been rotated 360°.

3) If ignitor still does not spark, proceed to step 6.

WARNING:

SHUT OFF THE GAS BEFORE

SERVICING THE UNIT.

6. Turn the power switch OF F.

7. Remove the burner head assembl y as outlined under "BURNER HEAD ASSEMBLY" in "REMOVAL AND REPLACEMENT OF PARTS" and check the following:

A. The gap between the spark probe and the

ground pin should be approximately 0.090" to 0.100". A djust as necessary. See diagram 5899 "BURNER HEAD ASSEMBLY" under "MAIN BURNER IGNITION CHECKS".

B. Inspect the ceramic flame r od insulator for

cracks or evidence of exposure to ex treme heat, which can permit leakage to ground. If either of these conditions ex ist, then replace ignitor rod and re-test.

1) I f replacing ignit or rod, loosen the ignitor rod mounti ng nut and remove the ignitor rod from the burner head assembly.

WARNING:

THE FOLLOWI NG ST EPS REQUIRE POW E R TO BE APPLIED TO THE UNI T DURING THE TEST. USE EXTREME CAUTION AT ALL TIMES.

8. Verify spark at electrode.

A. Place the assembly on the f loor and attach

a temporary ground wire from the burner ground on the heat ex c hanger to the burner head assembly.

B. Turn the power switch ON and press the

reset swit ch.

A. Remove ignit ion cable boot from t he

ignitor rod terminal.

B. Grasp the ignitor terminal and rot ate the

ignitor approximately 45°.

NOTE:

Touch igni tor term inal only and not the

ceramic insulator. C. Re-connec t ignition cable. D. Tur n the power switch ON and allow the

boiler to fill.

E. Press reset switch to start the ignition

process.

F24700 (October 2001) Page 38 of 68

C. Observe spark condition fr om ignitor.

1) I f a good spark fr om ignitor is present then the ignition system is working properly.

2) If ignitor is still not sparking, replace the ignition control module and r epeat steps 8A and 8B to check for proper operation.

3) After making the necessary component adjustments or replacements, re-assemble and check for proper operation.

VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS

COOKING COMPARTMENT

NOTE:

remove the right side compartment panel .

Intake Shut-Off Valve Adjustment (S t eam Flow)

1. With the ri ght side compartment panel

2. If t he steamer ready l ight is on, then pr oc eed to

3. If t he boiler is off, then turn main power switch

For access to com par tment cont r ols,

removed, open the i ntake shut-off v alve completely.

step 4.

ON and allow boi ler to heat up until steamer ready light comes on. Allow boiler to cycle 2 to 3 tim es, then proceed to step 4.

Door Sealing Adjustment

1. Check the door gasket quality. If dam aged or worn, replace as outl ined in "REMO V A L" under "COOKING COMPARTMENT DOOR(S)".

2. Loosen screws until the screw heads no longer touch the gasket plate.

3. Tighten screws until screw head touches gasket plate and at t hat point begin c ounting turns.

4. Tighten all screws approximately t wo turns.

5. Close the door and check for proper operat ion. A. If necessary, tighten all screws an

additional 1/2 turn and repeat step 5.

6. Repeat step 5 until the door closes properl y and no steam leaks are seen around t he gasket seal.

4. Turn both cooking timers on.

5. Monitor the boiler unt il heat source tur ns off.

6. At that t ime, adjust the intake shut - off valve until the manifold psi. The valve setting should be made while the boiler pressure is at the upper cycling lim it.

7. Monitor gauge reading 1 t o 2 cycles to ensure pressu re is set correc tly.

8. Once the valve is set, turn both cooking timers off and reinstall right side c ompartm ent panel.

pressure gauge reads 9 ±1

F24700 (October 2001)Page 39 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

Door Latch Adjustment

Should the cooker door jam and c an not be opened, DO NOT FORCE OR PRY occur.

First, try lifting up on the bottom of the door at the handle end to disengage the latch. If that does not work, remove the right side panel.

The striker that catches on the door latch is located behind the front fac e of the cooking cavity. Remove the nut f r om the stri k er and this will release it from the panel.

the door as damage wil l

4. Once the proper sl ot alignment has been set, hold the striker close to i ts base using a rag and vise grips, then tighten the strik er nut. Be careful not to damage the striker slot when tightening or door may not latch properly.

Once the nut and washer have been removed, door will open freely.

Remove any burrs on the stri k er that may cause the latch to stick. Rei nstall the striker and adjust, so door will not jam.

To adjust:

1. Reinstall the striker with the slot pointing upwards and hand tighten nut onl y .

2. Close the door to center the striker in the oval mounti ng hole.

3. Open the door and check the strikers’ sl ot for horizontal alignment. The slot on the striker must be kept hor izontal in order for the door latch to c atch it proper ly and latch.

NOTE:

to turn and change al ignment.

Do not over tighten as the striker will begin

F24700 (October 2001) Page 40 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

ELECTRICAL OPERATION

WATER LEVEL CONTROLS

Low Level Cut-Off & Differential Control

The steamer is equipped with three water level sensing probes (high, low and low level c ut-off) and a single water level c ontrol board (solid state). The water level control board perfor ms two functions: 1) Prov ide low level cut- off pr otection 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 pr obes.

The water level cont r ol (WLC) 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 i s provided t o the control by a series path through chassis ground (terminal 10). The other side of the transformer secondary (12VAC) i s attached to the probe that directs power to the other side of board r elay coil s (LLCO and HL) and to the Inverse Latc hing Relay (ILR) elec tronic ci r c uit on the board. A s water enters the boiler , it becomes part of t he water level control’s ci r c uit. When the water level in the boil er reaches a probe, that c ircuit is complet ed.

into the boiler. When the water level drops below the low level ( LL)

probe, power is removed from the inverse l atching relay, t he HL relay energiz es thr ough ILR-2 and HL contacts change state. The fill solenoid is energized through HL-3 to refill the boiler and the HL LED is lit. The HL relay and LED will toggle O N and OFF during a cooking cycl e as needed.

The inverse latching relay of the board is deenergized, 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 whic h ener gizes the high level (HL) relay, closes HL-3 norm ally open contacts, and illuminates the HL relay LED. With the HL-3 contacts closed, the boiler fill solenoid is energized and water begi ns filling the boiler.

When the water level reaches the l ow level c ut-off (LLCO) probe, t he LLCO relay i s energized and illuminates the LLCO LED. With the LLCO-2 contacts cl osed the heat source is then energized. The LLCO relay will remain energized and its LED will stay lit until the water level in the boiler drops below the LLCO probe. in the heating circuit must al so be sati sfied bef or e heating can start.

When the water level reaches the l ow level ( LL) probe, power to terminal 2 on t he WLC board is present but no switching oc c ur s.

After the water level reaches the hi gh level (HL) probe, the inverse latching relay of the board i s energized and locked through the l ow level pr obe (LL) and ILR-1 contacts. With ILR-2 contacts open, this de-energi z es the HL r elay and the HL LED goes out. With t he HL- 3 c ontacts open, the boi ler fill solenoid is de-energized, stopping t he flow of water

NOTE:

Auxiliary control(s)

F24700 (October 2001)Page 41 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

Auxiliary Low Level Cut-Off

This control serves as a safety bac k up to the mai n water level control (W LC) boar d to meet CSD-1 code requirements. The operation of the auxiliary control is identical to the low level c ut-off (LLCO) function of the main WLC board but performs a single function: 1) Provide auxiliary low level cut-off protecti on to shut off the heat source in c ase the water level drops below the low level c ut-off (LLCO) probe. A singl e LLCO probe, identical to t he LLCO probe on the main WLC boar d, is connected to the auxiliary control.

The auxiliary water level control (WLC) has input voltage (120VAC) acr oss terminals 11 and 12 which powers the primary si de of the transformer. On one side of the transformer secondary, power is provided to the contr ol by a series path through chassis ground (terminal 10). T he other side of t he transformer secondary (12VAC) is attached to the control t hat directs power to the other side of t he internal 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 r eac hes the LLCO probe, t he c ircuit is complet ed.

When the main power switch is turned ON, power is supplied to the auxiliary WLC 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 l ow level c ut-off (LLCO) probe, t he LLCO relay i s energized (LLCO-2 close) and the LLCO LED lights up. T he LLCO relay will remain energized and its LED will stay lit until the water level in the boiler dr ops bel ow the LLCO probe.

When the boiler stops filling, press the manual reset switch on the boiler base control panel . This turns off the low water li ght, energizes the combustion blower and allows the ignition cycle to begin.

F24700 (October 2001) Page 42 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

RELAY BOARD

Board Layout and LED Legend

The relay boar d P r ovides a cent r alized loc ation for wire harness connections and power transfer t hr ough board relays (K1-K7) to the other steam er c ontrols. Also, provides a condition or c omponent troubleshooting indi c ator by utilizing seventeen LED’S on the board to represent the status of the condition or component in t he operating sequence. W hen the condition for the component being monitored is satisfied or ac tivated, an LED will light to indicat e its proper operation. If the corresponding LED does not light then the condition or component has not been satisfied or is not activat ed.

LED LEGEND

LED ON = Condition satisfied or component activated. 1 LED OFF = Condition not satisfied or component de-activated.

LED DESCRIPTION LED DESCRIPTION

N1 Board powered (24vac). N10 Aux iliary water lev el satisfied (LLCO) and reset switch

N2 Auxiliary water le vel satisfied (LLCO). N11 Boiler operating pressure condition satisfied and reset

N3 High limit pressure switch closed. N12 Combustion blower ON. N4 Steamer is ready (ready light "green" is ON). N13 Combustion blower air pressure switch satisfied. N5 Auxiliary water level satisfied (LLCO) and reset switch activated. N14 Ignitio n module pilo t volta ge (PV) to board level timing

Low water condition exists (N2 LED ON) or previously existed. If

wate r level condition is satisfied and the reset switch is activated then N6 LED will turn off.

N7 Boiler pressure condition satisfied an d reset switch activated. N16 Ignition module main voltage (MV) to low wate r leve l

Boiler High pressure condition exists (N3 LED ON) or previously

existed . If boiler pressure condition is satisfied a n d th e reset switch is activate d then N8 led will turn o ff.

N9 Cycling pressure switch CL O SED “call for heat”.

: 1. At initial power on, N6 & N8 le d ’s will be ON until conditions are satisfied and reset switch is activated.

NOTES

NOTE: 2. Board level timing circuit energized and powers pilot gas valve for a pproximately 15 seconds then de-e nergizes.

N15 2Pilot voltage (PV) to pilot gas va lve.

N17 Low water leve l satisfied (LLCO) and main volta ge (MV)

activa ted.

switch activated.

circuit.

contacts (LLCO) on water board.

from ignition module is supplied to main gas valve.

F24700 (October 2001)Page 43 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

Boiler Operational Status (LED Indicator)

Use the tables below to deter mine the operational status of a component or c ondition by utilizing the LED indicat ors on the board. The operational state’s are divided into categori es A t hru F.

Initial Conditions: (STATE A)

- 120V, water and gas supplied t o steamer

- Power Switch ON

- HIGH PRESS and LOW WATER li ghts ON (amber, f r ont control panel)

- Green “ready” li ght OFF

- Water is filling boiler

LED

N1 X 24V supplied to relay board N2 X Aux Water l evel not satisfi ed Aux. LLCO c ontacts OPEN N3 X High li mit pr essure switch sati sfied K2 energized - K2(1) CLOS E , K2(2) CLOSE

N4 X N5 X Reset switch is not being ener gized

N6 X Aux Water l evel is/was not satisfied K3 not energized N7 X Reset switch is not being ener gized

N8 X

N9 X

N10 through N17 remain OFF

Aux Water Level Satisf ied: (STATE B)

- Green “ready” l ight ON (ready li ght remains ON, until a LOW WATER or HIGH PRESSURE) condition occurs.

STATUS

ON OFF

DESCRIPTION ELECTRICAL COMPONENTS CONDITION

Aux Water level is initially not satisfied. Therefore N4 is OFF

High Limit pressure switch is/was not sati sfied

Cycling pressure switch is closed and unit is calling for HEAT

K1(1) OPEN

K4 not energized

Status of LE D’s are t he same as “Initial Conditi ons” except for the following:

LED

N2 X Aux water level is satisfied

N4 X

Reset Engaged: (STATE C)

User presses/engages the RESET button

- LOW WATER and HIGH PRESSURE li ghts OFF (amber, front control panel)

F24700 (October 2001) Page 44 of 68

STATUS

ON OFF

DESCRIPTION ELECTRICAL COMPONENTS CONDITION

Aux LLCO water level and high li mit are satisfied. Green “ready” l i ght ON.

Aux. LLCO r elay energized, Aux. LLCO contacts CLOSED

K1 energized - K1(1) CLOSE

VHX SERIES STEAMER - ELECTRICAL OPERATION

LED

DESCRIPTION ELECTRICAL COMPONENTS CONDITION

ON OFF

N1 X same as “state A” N2 X same as "state B" N3 X same as “state A” N4 X same as "state B

STATUS

N5 X

N6 X

N7 X

N8 X

Reset switch is/was momentarily energized

Aux Water level is satisfied. (Amber WATE R light OFF)

Reset switch is/was momentarily energized

High Limit is satisfied. (Amber HIGH PRESS OFF)

N9 X same as “state A” N10 X

N11 X

High li mit is satisfied and r eset switch energized

Aux Water level is satisfied and reset switch energized

K3 energized - K 3( 1) CLOSE (locking circuit)

K3 energized - K 3( 1) OPEN

K4 energized - K 4( 1) CLOSE (locking circuit)

K4 energized - K 4( 1) OPEN

K3(2) CLOSE

K4(2) CLOSE, K 5 energized

N12 X Air intake blower receiving power K5(1) CLOSE N13-N17 remai n OFF

Air Pressure Switch Satisfied : (STATE D)

Assume water level control “LLCO” is satisfied (LLCO contacts closed) N1 thru N12 same as “Reset Engaged: (state C) "

STATUS

LED

DESCRIPTION ELECTRICAL COMPONENTS CONDITION

ON OFF

N13 X Air pressure switch sati sfied 24V to igniti on module (term 6) N14 X Ignition module P V c oil energiz ed PV CLOSE, 24V to K7

N15 X

N16 X

N17 X

Pilot gas valve is energi z ed.

N15 and the pilot gas valve will

Note:

be ON for approximately 15 seconds, then turn OF F.

Ignition module PV coil energized, pilot igniti on flame is detected

Water level board LLCO is satisfied and main gas valve is recei ving power.

K7 energized K7( 1) CLOSE, relay boar d timer circuit energized and starts time count. K6 energized K6(1) CLOSE, pilot gas valve coil energized for 15 sec. only.

MV CLOSE, 24V to water level board LLCO contacts

Main gas v alve c oil energi z ed, main burner lights and flame c ontinues to be detect ed.

Burner ON, Boiler Heating to generate steam: (STATE E)

All LED’s ON except N6 & N8, N15 (still OFF from state D)

Burner OFF, Boiler P ressure Satisfied : ( S TATE F)

These LED’s should be OFF - N6, N8, N9, , N10, N11, N12, N13, N14, N15 (still OFF from state D) N16 & N17 These LED’s should be ON - N1 thru N5, N7

F24700 (October 2001)Page 45 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

SEQUENCE OF OPERATION

NEW STYLE CONTROLS - BOILER This sequence of oper ation is writt en for boiler

bases with the new style boiler c ontrols. See "BOILER CO NTROL STYLES" under "GENERAL". Refer to schematic diagram TS P 1480.

Initial Fill and Preheat

Conditions.

A. Power switch OFF. B. Boiler connected to correc t voltage

(120VAC). C. Boiler properl y gr ounded. D. Gas and water supply valve(s) ON. E. Main gas valv e manual valve in ON

position F. Cyc ling pressure switch closed. G. High limit pressure switch closed. H. Col d water c ondenser (CWC) thermostat

open. I. Automat ic blowdown solenoid valve

(A.B.D. ) open and boiler empty.

2. Turn power switch ON. A. Automatic Blowdown valve (N.O.) is

energized and close.

B. Water level control (WLC) energized.

1) High level (HL) rel ay energized, HL-3 contacts (N.O.) close.

a. Fill solenoid energized, water

begins filling the boiler (fill time 4-11 min.).

2) HL LED lit.

C. Auxiliary water level control is powered.

1) Aux. LLCO N.O. contacts remain open.

D. 120VAC to one side of K5(1) N .O., K1(1)

N.O., K3(1) N.O., K4(1) N.O. contacts.

N6 lit.

thru K3(1) N.C.

N8 lit.

thru K4(1) N.C.

N1 lit.

and relay board is powered.

1) 24VA C to one side of auxiliary water

Low Water light (c ontrol panel) lit

Hi Pressure li ght (control panel) lit

24VAC transf or mer is energiz ed

level control LLCO contacts (N.O.).

N3 lit.

K2 energized through the high

limit pressure switch contacts (N.C.). a. K2 contacts K2(1) N.O. & K2(2)

N.O. close, no power transferred.

N9 lit.

3. Water level reaches LLCO probe for both water level control and auxiliary low level control.

A. LLCO relay on water level board

energizes, LLCO c ontacts (N.O.) close

1) LED on boar d lights.

B. Aux. LLCO r elay energizes, aux. LLCO

contacts (N.O.) close.

1) LED on boar d lights.

3) K1(2) N.O. close.

NOTE:

reset swit ch pressed.

NOTE:

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.

NOTE:

start combustion blower & ignition cycle but it’s preferred to let the boiler fill the to the "High Level" before c ontinuing.

4. Water reaches LL (low level) probe.

5. Water reaches HL (high l evel) pr obe. A. Fill solenoid is de-energized. B. HL-LED

6. Manual reset switch pressed. A.

NOTE:

K3(1) N.O. locking circuit.

No power is transferred until manual

The LLCO and aux. LLCO relays wil l

The reset switch coul d be pr essed to

N5 lit.

Relay K3 remains energized t hr ough

2) Low water light (control panel) goes

N7 lit.

24VAC to one side of K3(2) N.O. contacts through cycling pressu re switch N.C.

N2 lit.

K1 is energized. a. K1(1) N.O. close.

N4 lit.

K3 is energized ( 120V A C) .

N6 goes out

close and K3(1) N.C. contacts open.

out.

N10 lit.

a. 24VAC to one side of K4(2) N.O.

K4 is energized ( 120V A C) .

Ready light (green) on the control panel manual r eset switch, ON.

. K3(1) N.O. contacts

K3(2) N.O. contacts close.

contacts.

F24700 (October 2001) Page 46 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

NOTE:

Relay K4 remains energized t hr ough

K4(1) N.O. locking circuit.

N8 goes out.

K4(1) N.O. contacts

close and K4(1) N.C. contacts open.

2) High pressure light (c ontrol panel) goes out.

N11 lit.

K4(2) N.O. contacts close.

1) K5 is energized (24VAC) . a.

N12 lit.

K5(1) N.O. contacts

close. a) Combustion blower start s.

N13 lit.

When the combustion blower generates suff icient air pressure, the air pressure switch N.O. contacts close.

A. Ignition module is powered (24VAC).

1) I gnition module starts sparking.

N14 lit.

Pilot voltage (PV) N.O.

contacts cl ose. a. K7 is energized.

a) K7(1) N.O. contacts close.

3) 15 sec. timer circuit (board level, solid state t imer) energized and tim ing of pi lot gas valve ON tim e begins.

a. K6 energized.

N15 lit.

K6(1) N.O. close.

4) Pilot gas valve energized, pilot valve opens for gas to f low.

B. Pilot flame established. Micro amp flam e

"sense" current rectifi ed to ignition module through igni tion cable.

1) Spar k ing stops.

N16 lit.

Main voltage (MV ) N.O.

contacts cl ose. a.

N17 LED lit.

Prov es LLCO on

water level board cl osed.

b. Main gas v alve opens, burner

lights and boiler begins to heat up.

C. 15 seconds after ignit ion module

energized, r elay board timer circ uit times out.

N15 goes out .

K6 de-energized.

a. Pilot valve cl oses, gas flow stops

to pilot.

NOTE:

If pilot ignition i s not est ablished within the allotted 15 seconds, the ignition m odule continues to spark. To attempt to reli ght the

pilot, quickly cycle the reset switch to prevent the boiler from draining. If the pilot is not established within 90 seconds from t he ignitor module being energized, the ignition module locks out power to the gas valves. The m odule remains locked out unti l the power switch is turned to OF F then ON and the manual reset switch is pressed to r e-start t he igniti on trial cycle.

D. 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 condensing any steam vapors bef or e exit ing the drain. The CWC sol enoid is powered through the CWC cycling thermostat.

NOTE:

On initial cold startup only, the boiler pressure may overshoot and cause the mechanic al pressure relief v alve to open momentarily.

E. As long as the igni tion control module

senses a burner flam e, the internal main voltage (MV) contacts (N.O.) on the ignition module remain closed, and main gas valve stays ON.

NOTE:

PV N.O. contacts are also closed, but K6 contacts are open t o k eep pilot valve closed.

8. Boiler st eam pressure reaches upper limit set point of 10 PSI (Approx. 15 minutes).

A. Cycling pr essure switch open.

N9, N10, N11, N12, N13 go out.

a. K5 de-energized.

a) K5(1) N.O. contacts open.

b. Combustion blower is de-

energized. a) Air pressure switch opens.

B. Ignition module is de-energized

1) PV and M V contacts open. a.

N14, N16, N17 go out.

b. Main gas v alve c loses, burner

goes out.

c. K7 de- energized.

a) K7( 1) open

9. Boiler st eam pressure drops below lower limit set point of 8 PSI and the cycling pressure switch close.

A. Boiler st eam pressure is maintained by the

cycling of the pressure switch between the

F24700 (October 2001)Page 47 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

upper and lower set point limits. The cycling pressure switch continues to energize and de-energize the heati ng circuit t o cycle the burner ON and OFF.

This sequence conti nues until one of the following occurs:

1) Power switch is turned OFF.

2) Boiler water l evel dr ops bel ow the LLCO probes for t he main water l evel control ( WLC) and t he auxiliary low level control.

3) Boiler pressurizes to 15 P S I, 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) Fill solenoid is energized.

3) HL LED c omes ON.

2. Water reaches LL (low level) probe.

3. Water reaches high level pr obe. A. HL relay is de-ener gized.

1) HL-3 (N.O.) contacts open.

2) Fill solenoid is de-energized.

3) HL LED goes out.

4. The water refill cycle will occur whenever t he water level is below the low level probe and will not affect the operation of either the preheat or cook cycle.

Boiler Blowdown/drain

1. Power switch turned OFF. A. Automat ic blowdown solenoid valve (N.O.)

is de-energized and valve opens to drai n the boiler .

B. Power is removed fr om all c omponents

except cold water condenser (CWC) thermostat and solenoid v alve. The CWC thermostat cycles as necessary to lower the discharge temperature of the water

and condense steam going into the drain. OLD STYLE CONTROLS - BOILER This sequence of oper ation is writt en for boiler

bases with the old style boiler contr ols. See "BOILER CO NTROL STYLES" under "GENERAL". Refer to schematic diagram 5480.

Initial Fill And Preheat

1. Conditions.

A. Power switch OFF.

B. Boiler connected to correc t voltage

(120VAC).

1) Power to cooking com par tment controls. See "COOKING COMPARTME NT CONTROLS" later in this section.

C. Boiler properl y gr ounded ( boiler and water

level controls share a common ground) D. Gas and water supply valve(s) ON. E. Main gas v alve ON. F. Cyc ling pressure switch CLOSED. G. High limit pressure switch CLOSED. H. Col d water c ondenser (CWC) thermostat

OPEN. I. Automatic blowdown valv e (A.B.D.) OPEN

and boiler empty.

2. Turn power switch ON. A. Relay R4 energiz ed and R4 contacts

(N.O.) CLOSE. B. Power ON light (red) comes ON. C. Blowdown solenoid valve is energized and

CLOSES. D. Auxiliary water level control is powered.

1) Aux. LLCO N.O. contacts remain OPEN (Aux. LLCO relay deenergized).

E. Low water level light ( amber) com es ON.

NOTE:

The low water indicator light will remain ON and the safet y circui t de-energized until the water level in the boiler reaches the auxiliary low level cut-off probes (aux. LLCO, minimum level) f or the aux. water level control, and the manual reset switc h is pressed.

F. High pressure light (amber) com es ON.

NOTE:

The high pressure indicator light will remain ON and the safety c ircuit de- ener gized until the manual reset button is pressed (high limit pressure switch m ust be c losed).

G. Power is connected through t he high limit

pressure switch contacts (N.C. ) to one side of the push butt on r eset switc h.

H. Water level control is powered (Low Level

Cut-off & Differential Contr ol).

1) High level (HL) rel ay is energized, HL contacts (N.O.) CLOSE

a. HL LED light s up. b. Fill solenoid is energized and

water begins filling boiler (fill tim e 4-11 min.).

F24700 (October 2001) Page 48 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

3. Water level reaches LLCO (low water level cutoff) probe for the water level control and to the auxiliary LLCO probe for t he auxiliary low level cut-of f control.

A. LLCO relay energizes, LLCO contacts

(N.O.) CLOSE and LED light s.

NOTE:

No power is transferred until i gnition

sequence starts. B. Aux. LLCO r elay energizes, LLCO

contacts (N.O.) CLOSE and LED lights.

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 t he power switch is turned OFF.

4. Water reaches LL (low level) probe.

5. Water reaches HL (high l evel) pr obe.

A. Fill solenoid is de-energized.

6. Press the manual r eset switc h.

A. Relay coil (R1) energiz ed.

1) High pressure light turns OFF.

B. Relay coil (R3) energiz ed.

1) Low water light turns OFF.

2) T r ansformer ( T1) energized.

7. 24VAC is connected through the cycling

pressure switch contacts to the foll owing components:

A. Normally open (N.O.) side of the air

pressu re switch.

NOTE:

No power is transferred until ai r

pressure switch CLOSES. B. Relay coil (R2) is energi z ed and R2

contacts (N.O.) CLOSE.

1) 120VA C is supplied to the combustion air blower and blower starts.

C. Onc e the combustion blower devel ops

sufficient pressure, the air pressure switch CLOSES.

1) 24VA C is then applied to the Ignition control m odule and the ignition cycle starts.

a. Pilot voltage (PV) N.O. contacts

CLOSE.

b. Pilot gas valve energized, pilot

valve opens for gas to fl ow and Ignitor begins sparking to light pilot.

2) Pilot i gnition i s established (pilot lit) and a micro amp flame "sense" current i s sent back to the ignition module t hrough the ignition cable.

3) Main voltage (MV) N.O. contacts CLOSE.

a. Main gas v alve OPENS, burner

lights and boiler begins to heat up.

NOTE:

As boiler heat s up and bui lds pressure, some by-pass water/steam is produced which runs into the steam drain box . This causes the cold water condenser (CWC) solenoid t o cycle, cooling t he drain water and condensing any steam vapors before exiting the drain. T he CWC sol enoid is powered by the CWC thermostat.

NOTE:

On initial cold startup only, the boiler pressure may overshoot and cause the mechanic al pressure relief v alve to OPEN momentarily.

b. As long as the igni tion control

module senses a burner f lame, the internal main voltage (MV) contacts (N.O.) on the ignition module remain closed, and main gas valve stays ON.

c. I f sparking is allowed to conti nue

for a total of 90 seconds, t hen the ignition module locks out power to the gas valve ( pilot valve and main valve remai n closed). The module remains locked out unt il the power switch is turned to OFF then ON and the manual reset switch is pressed to re-start the ignition trial cycle.

8. Boiler st eam pressure reaches upper limit set point of 10 PSI (approximat ely 15 min).

A. Cycling pressure switch opens and power

is removed fr om the f ollowing components:

1) Combustion air pressure switch normally open (N.O.) terminal.

2) Relay coil ( R2) returning R2 contacts to there N.O. shelf state.

a. Combustion air blower de-

energized.

B. Ignition control module is de-energized,

PV and MV contacts OPEN.

1) Main gas solenoid valve deenergizes, gas f low shuts OFF and burner goes out.

9. Boiler st eam pressure drops below lower limit set point of 8 PSI and the cycling pressure switch CLOSES.

A. Boiler st eam pressure is maintained by the

cycling of the pressure switch between the

F24700 (October 2001)Page 49 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

upper and lower set point limits. The cycling pressure switch continues to energize and de-energize the heati ng circuit t o cycle the burner ON and OFF.

This sequence conti nues until one of the following occurs:

1) Power switch is turned OFF.

2) Boiler water l evel dr ops bel ow the LLCO probes for t he main water l evel control and t he auxiliary low level cutoff control

3) Boiler pressurizes to 15 P S I, 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 N.O. contacts CLOSE, fill solenoid is energized and HL LED comes ON.

2. Water reaches LL (low level) probe.

3. Water reaches high level pr obe. A. HL relay is de-ener gized.

1) HL N.O. contacts OPEN, fill solenoid is de-energized and HL LE D goes out.

4. The water refill cycle will occur whenever t he water level is below the low level probe and will not affect the operation of either the preheat or cook cycle.

Boiler Blowdown/Drain

1. Power switch turned OFF. A. Boiler blowdown sequence starts. B. The automatic blowdown solenoid valve

(N.O.) is de-energized and valve OPENS to drain the boiler.

C. Power is removed from all com ponents

except cold water condenser (CWC) thermostat and solenoid v alve. The CWC thermostat cycles as necessary to lower the discharge temperature of the water and condense steam going into the drain.

COOKING COMPARTMENT CONTROLS

1. Conditions. A. Doors shut (closes the N.O. door switch

contacts). B. Cooking ti mers OFF. C. Compartment pr essure switch contacts

OPEN.

2. With boil er at operating pressure. A. Cooking com partment pr essure switch

CLOSES (approx. 3 PSI).

1) Cooking compart ment ready light (green) com es ON.

3. Start a cook cycle. A. Insert product into steamer and c lose door. B. Set a cook time.

NOTE:

On initial startup, if a cooking ti mer is set immediately after the ready li ght comes on, steam solenoi d c hattering will be heard (oil canning) and the r eady lights will flash for several seconds. This condition is caused by the mani fold steam pressure being on the "fringe" of t he pr essure switch set point. When a cook timer is set, the c ompartm ent steam solenoid valve opens causing the manifold steam pressure to drop, sl ightly below the pressure switch set point. At the same time, steam pressure is still increasing in the boiler. This opposing condi tion causes a pressure "bounce" to occur . After the steam pressure passes approximat ely 4 psi this condition subsides. During norm al operation, this conditi on will not be seen.

C. Contac ts 1/3 of cook t imer CLOS E and

tim er motor is energized.

1) Compartment steam solenoi d 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 compartm ent until a c ook time is set. This energizes the steam solenoi d valve of the cooki ng c ompartm ent to allow steam f low.

4. Tim e expires on timer. A. Tim er contacts 1/3 OP E N, tim er motor de-

energized.

B. Steam solenoid valve de- energizes,

stopping the flow steam into compartment.

C. Timer cont ac ts 4/1 CLOSE and energiz e

buzzer until manual ly turned OF F.

D. Cooking light ( r ed) goes out and Ready

light ( green) comes ON.

5. Tim er manually turned OFF. A. Contacts 1/4 OPE N B. Alarm Buzzer de-energiz ed 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.

F24700 (October 2001) Page 50 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

- THIS PAGE INTENTIONALLY LEFT BLANK -

F24700 (October 2001)Page 51 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

SCHEMATICS

Models Bu ilt After 5/25/00 (New Style Boil er Controls)

F24700 (October 2001) Page 52 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

F24700 (October 2001)Page 53 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

Models Built Before 5/25/00 (Old Style Boiler Controls)

F24700 (October 2001) Page 54 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

Cooking Compartment Controls

F24700 (October 2001)Page 55 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

WIRING DIAGRAMS

Models Bu ilt After 5/25/00 (New Style Boil er Controls)

F24700 (October 2001) Page 56 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

F24700 (October 2001)Page 57 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

Models Built Before 5/25/00 (Old Style Boiler Controls)

F24700 (October 2001) Page 58 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

F24700 (October 2001)Page 59 of 68

VHX SERIES STEAMER - ELECTRICAL OPERATION

Cooking Compartment Controls

F24700 (October 2001) Page 60 of 68

VHX SERIES STEAMER - TROUBLESHOOTING

TROUBLESHOOTING

BOILER BASE CONTROLS

WARNING

Models with new style cont r ols: Before per forming any of t he troubleshooting c hec k s l isted below, remove the cover from the main control box and check the condition of the LED’S on the relay boar d for the status of the conditi on or component in the operating sequence. B y utilizing the troubleshooting LED’S, t he Service Technician can quickly and easily deter mine if a component is funct ioning properl y or in need of repair. Refer to "RELAY BOARD" under "ELECTRICA L OPERATIO N" .

Steamer does not operate. 1. No power to steamer .

Steamer ON, cannot reset low water condition.

: CERTAIN PROCEDURES IN THIS SECTION REQUIRE ELECTRICAL TESTS OR

SYMPTOM POSSIBLE CAUSES

2. F1 Fuse open.

3. Malfunctioning power switch.

4. Malfunctioning power switch latching relay (old style contr ols only).

1. Low water level in boiler. A. Water inlet valve(s) OFF. B. Fill solenoid not receiving power, c logged or

malfunctioning.

2. Manual blowdown valve on water level pr obe housi ng open.

3. Improper ground.

4. Lime scale build-up auxiliary water level probe.

5. Malfunctioning reset switch.

6. Malfunctioning auxiliary water level control board.

Steamer ON, cannot reset high pressure condition.

Steamer ON, reset switch pressed but blower does not operate when calling for heat.

(boiler pr essure within operating l imits)

1. Excessiv e pr essure in boiler.

2. Malfunctioning reset switch.

3. Malfunctioning high pr essure limit switch.

4. Malfunctioning pressure switch lat c hing relay (old style contr ols only).

1. Blower malfunctioning or loose connecti on on blower cord.

2. 24 VAC transformer malfuncti oning.

3. Malfunction in cycling pressure switch.

4. Malfunctioning "Low Water" or "Hi Pressure" light not indicat ing true condit ion.

5. Blower relay malfunct ioning (old sty le controls onl y ).

F24700 (October 2001)Page 61 of 68

VHX SERIES STEAMER - TROUBLESHOOTING

SYMPTOM POSSIBLE CAUSES

Blower operati ng, no pilot gas flow. 1. Main gas supply tur ned OFF.

2. Ignition module lockout. Turn power switch OF F for several seconds then ON to reset the module.

3. Air pressure switch: A. Not m ounted in true verti c al position. B. Incorrect pressure setting. C. M alfunct ioning switch.

4. Malfunctioning Igni tion module.

5. Malfunctioning pilot gas valve.

6. Blocked or dirty pilot gas orific e.

Pilot flame not proving or lighting m ain burner.

Main burner not lighti ng c or r ec tly or excessive ignition noise.

Excess combustion noise or combustion induced harmonics.

1. Gas not ON.

2. Inc orrect manifol d pr essure for pilot gas.

3. Poor connection between igniter and ignition cabl e.

4. Fouled spark igniter.

5. Inc orrect gap in spark igniter.

6. Faulty igniter or crack ed insulation.

7. Improper ground.

8. Low water level in boiler or boiler not filling.

9. Flame sensing current too low.

10. Crac k ed or incorrect bur ner head attachment .

11. I nc or rect igni ter positioning.

12. I nc or rect pil ot orif ice.

1. Blocked or dirty air ori fice on blower.

2. Insuffi c ient gas supply pressure.

3. Inc orrect gas pilot pressure.

4. Inc orrect gas mani fold pressure.

5. Pilot flame not sensing c or r ec tly.

6. Burner tube insulation broken or deteriorated.

7. Blocked or restri c ted flue.

8. Inc orrect pilot or main gas burner orif ice size.

1. Blocked or dirty air ori fice on blower.

2. Inc orrect gas mani fold pressure.

3. Insuffi c ient gas supply pressure.

4. St eam v apor s introduced int o blower inlet.

5. Loose f lue connecti ons.

Boiler not maint aining set pressure and/or excessive burner on t ime.

F24700 (October 2001)

1. Leaking boiler blowdown valve.

2. Manual blowdown valve on water level pr obe housi ng open.

3. Malfunctioning 13 psi overshoot relief valve.

4. Low incoming gas supply pressure.

5. Excessiv e load on steam outlet.

Page 62 of 68

VHX SERIES STEAMER - TROUBLESHOOTING

SYMPTOM POSSIBLE CAUSES

Gas odor. 1. Leaks i n pipe fi tting connect ions or components.

2. Leaking pressure tap plug on pilot or main gas valve; loose or missing pressure adjustment screw cap on main gas valve.

3. Leaking gaskets in air/ gas mixt ur e path.

4. Pilot or main gas valve malfunction (improper venti ng or vent blocked).

5. Inc orrect gas pressure.

6. Malfunctioning gas burner.

7. Blocked or dirty air ori fice on blower.

8. Blocked or dirty gas orifice.

9. Malfunctioning blower.

10. No pilot ignition.

11. I mproper hood venting, vent blocked or room not vent ed properly.

Drain box leaking. 1. Cl og in drain l ine plumbing.

2. Drain restrict ed to size below 1-1/4" pi pe.

3. Drain extension plumbing not at the proper slope or plumbing too lengthy.

4. Grommet s not seal ing.

5. St eamer draining while under pressure and relief valve opening at the same time (flooding dr ain box).

6. Col d water c ondensi ng spray is "over spraying".

7. Drain box thermostat improperly set or malfunctioni ng.

Cold water condenser not operat ing properly.

Heat coming on without water in boiler (Dry firing).

Spark Ignitor not sparking. 1. Ignitor boot on i gnition cable loose, damaged or missing

1. Water supply val ves(s) turned off.

2. Col d water c ondenser solenoid not receiving power, inoperative or valve plugged.

3. Col d water c ondenser t her mostat malfunct ion or needs adjustment.

4. Plugged spray nozzle.

5. Water supply pressure high (im pr oper valve operation).

1. Li me scale build-up on water level probes (shorted to gr ound) .

2. Retention of water in probe housing (assembly or aux.LLCO).

3. Water level control malf unc tion.

4. Aux. water level control malfunct ion.

causing excessive ignition voltage leakage.

2. Loose, brok en or damaged lead wires (inc luding ground) from ignition module to ignitor.

3. Poor ground on ignitor assembly.

: Items 4, 5 & 7 see "IGNITION CONTROL MODULE

NOTE

CHECKS" in "SERVICE PROCEDURES AND ADJUSTMENTS".

4. Ignition module not receiving power.

5. Ignition module malfunction (no output voltages or spark) .

6. Ceramic flame r od insulator on ignitor cracked or damaged from extreme heat.

7. Inc orrect spark gap setti ng.

Page 63 of 68

F24700 (October 2001)

VHX SERIES STEAMER - TROUBLESHOOTING

SYMPTOM POSSIBLE CAUSES

Boiler Slow to Pressurize (over 15 min. t o achiev e operating

pressure)

1. Low water supply pressure, i nline water strai ner c logged or fill solenoid valve malfuncti on. See "INLINE WATE R S TRAINER CLEANING" and " FILL AND COLD WATER SO LE NOID VALVES" in "SERVICE PROCEDURES AND ADJUSTMENTS".

2. Boiler blowdown solenoid valve clogged and not full y c losing. Check for a slow leak out of steamer drain. If not able to v er ify, then proceed to step 3. If blowdown solenoid valve appears to be functioning properly, then proceed t o step 4.

3. Turn power switch OFF, disconnect lead wires from blowdown solenoid and remove it for inspection.

4. A heavy build-up of scalants has coated the inter ior of t he boiler, creating an i nsul ating effect. E xami ne interior of boil er as outlined under “BOILER” in "SERVICE PROCEDURES AND ADJUSTMENTS".

5. Low incoming gas pressure is reducing BTU output. A. Verify gas supply line to the steam er is a mini mum of one

inch diameter (ID).

B. Check inc oming line and mani fold gas pressures as

outlined i n " G AS MANIFOLD PRESSURE ADJUSTMENT" under "SERVICE P ROCEDURES AND ADJUST M E NTS".

6. Gas valve malfunction. A. Check inc oming line and mani fold gas pressures as

outlined i n " G AS MANIFOLD PRESSURE ADJUSTMENT under "SERVICE P ROCEDURES AND ADJUST M E NTS".

Boiler will not heat or build pressure. 1. Gas not on.

2. Power/r eset switc h assembly mal functi on.

3. Boiler not filling - check fill solenoid for power, cl ogging or malfunction.

4. Gas pilot and/or gas manifold pressure low. See "GAS PILOT PRESSURE ADJUSTMENT" and "GA S M A NIFOLD PRESSURE ADJUSTMENT" in " S E RV ICE PROCEDURES AND ADJUSTMENTS".

5. Cycling pressure switch open or set too high. Steam er is cycling on high li mit.

6. Hi gh limit pressure switch open and not re-sett ing (malfunction).

7. Water t oo "pure" for pr obes to pr operly conduct electric ity.

Items 8 & 9 see "WATER LEVEL CONTROLS TEST"

Pressure relief v alve( s) opening or leaking.

NOTE:

in "SERVICE PROCEDURES AND ADJUSTMENTS".

8. Water Level Cont r ol malfuncti on.

9. Aux. Water Level Control malfunction.

1. Pressure overshoot on initial star tup or long burner on times under heavy usage.

2. Pressure relief valve m alfunct ion.

3. Cycling pressure switch set to hi gh.

4. Hi gh limit pressure switch not set correc tly or m alfunct ioning.

F24700 (October 2001)

Page 64 of 68

VHX SERIES STEAMER - TROUBLESHOOTING

SYMPTOM POSSIBLE CAUSES

Steam out put low or slow cooking. 1. Cooking Compartment.

A. Block ed steam inj ec tor ports. (Open door, press door

switch button and verify good steam flow into

compartment). B. Steam solenoid valve not fully opening or blocked. C. S team int ak e shut- off valve cl osed or out of adjustment.

See "INTAKE SHUT-OFF VALVE ADJUSTMENT (STEAM

FLOW)" in "SERVICE PROCEDURES AND

ADJUSTMENTS".

2. Boiler Base. A. Cycling pressure switch malfuncti on or needs adj ustment. B. Steam header line (supply) blockage. C. Heavy amount of condensate in the pressure controls

steam supply line. D. P r essure rel ief valve leaking. E. Steam supply lines leaking badly.

Steamer leaks water. 1. Loose water, steam or drain l ine connections (t op or base).

2. Heat exchanger gasket not seal ing.

3. Leak at gauge glass.

Boiler water level too high. 1. Fill solenoid does not shut off.

2. Li me scale build-up (moist) on High level probe ( open c ircuit) .

3. Water level control malf unc tion.

Boiler does not fill. 1. Water supply not on.

2. Fill solenoid not openi ng or plugged.

3. Water level control malf unc tion.

Burner won’t light. 1. G as not on.

2. Power/r eset switc h assembly mal functi on.

3. Boiler not filling - check fill solenoid for power, cl ogging or malfunction.

4. Air pressure switch: A. Not m ounted in true verti c al position. B. Incorrect pressure setting. C. M alfunct ioning switch.

5. Ignition module not receiving power.

6. St eamer not properly grounded and/or pol ar ity of incomi ng power is incorrect on spark igniti on systems.

7. Ignition module malfunction.

8. Gas valve malfunction.

9. Water t oo "pure" for pr obes to pr operly conduct electric ity.

10. Cyc ling pressure switch open or set too high. Steam er is cycling on high li mit.

11. High limit pressure switch open and not re- setting (malfunction).

12. Water level control malfunction.

13. Aux. water level control malfunct ion.

Page 65 of 68

F24700 (October 2001)

VHX SERIES STEAMER - TROUBLESHOOTING

COOKING COMPARTMENT CONTROLS

SYMPTOM POSSIBLE CAUSES

Cooking com partments do not oper ate. 1. No power to compartment s.

2. Pressure i n boiler is bel ow compartment pressure switch setting.

3. Door switc h malfunction.

4. Timer malfunction.

5. Malfunctioning pressure switch in compartm ent.

6. Verify correct com par tment wiring and functioning components.

Steam generated inside compartment when timer is off .

Tim er motor does not run. 1. Door open or door switc h inoperative.

Door not closi ng pr oper ly. 1. Door latch assembly malfunction or out of adjustment. See

Door won’t open. 1. Latch won’t release. See "DOOR LATCH ADJUSTM E NT" in

Buzzer not operating. 1. T imer malfunction.

Compartment leaks water around door or water accumulating i n c ompartm ent .

Steam leaks around door. 1. Worn gasket - See "DOOR SEALING ADJUSTMENT " in

1. St eam supply solenoi d not fully closing (c logged or dirty ) . See "FILL AND COLD WATER SOLENOID VALVES" in "SERVICE PROCEDURES AND ADJUSTMENTS".

2. Timer contacts 1 & 3 closed.

2. Timer not getting power.

3. Timer motor inoperative.

"DOOR SEALING ADJUSTMENT" in "SERVICE PROCEDURES AND ADJUSTMENTS"

2. St r iker adjustment. See "DO OR LATCH ADJUSTM E NT" in "SERVICE PROCEDURES AND ADJUSTMENTS".

"SERVICE PROCEDURES AND ADJUSTMENTS".

2. Buzzer malfunction.

1. Compartment drain screen clogged.

2. Drain line obstruc ted or not to an open gap drai n.

3. St eamer not level.

"SERVICE PROCEDURES AND ADJUSTMENTS".

2. Damaged gasket.

3. Drain line obstruc ted or not to an open drai n.

F24700 (October 2001) Page 66 of 68

VHX SERIES STEAMER

- NOTES -

F24700 (October 2001)Page 67 of 68

VHX SERIES STEAMER - CONDENSED SPARE PARTS LIST

CONDENSED SPARE PARTS LIST

NEW STYLE CONTROLS ONLY

VHX24G, VHX24G5, MHB24G

PART NUMBER DESCRIPTION NOTES

853582-1 Igniter, Sensor 850778-1 Switch, Air Pressure 850735-1 Blower, Com bustion 354344-4 Valve, Pilot Gas 851315-1 Valve, Main G as 851316-1 Valve, Pressure Reli ef 13 psi 880413 Valve, Pressure Reli ef 15 psi 817222 Valve(s), Cold Water Condenser and Boiler Fill 833488 Switch, Pressure Cycling 851578-1 Switch, Pressure Hi gh Limit 844062-1 Thermostat, Condenser/drain Box 411500-12 Transformer, 120vac to 24vac 417980-1 Module, Ignition Control 844070-1 Control, Aux. Low Water Board 844069-1 Control, Water Board 852081-1 Circui t, Breaker 5amp Slow Blow (fuse) 851613-1 Boiler, Drain Valve (bl owdown) 851618-1 Power Cord, drain Valve 844130-3 Cable, Ignitor 18" 853275-1 Switch assembly , on/off, reset & l ights 853273-1 Relay Board 411690-1 Tim er , Cooking 843836 Steam Solenoid Valves, Cooki ng Compartment

F24700 (October 2001) Printed in U.S.A.

Vulcan-Hart MHB24G, VHX24G5, VHX24G User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual