Market Forge Industries PLUS-TWELVE ST-12 Instruction manual

35 Garvey Street lEverett lMA l02149
Tel: [phone] lFax: [phone] lFax: (Outside MA) 1-800-227-2659
E-Mail: custser[email protected] lWebsite: http://www.mfii.com
INSTALLATION, OPERATION & MAINTENANCE MANUAL
Form Number: S-4475 Rev: A 06/03 Printed in U.S.A.
PLUS-TWELVETM
PRESSURELESS STEAM COOKER
Warning
Improper Installation, adjustment,
alteration, service, or maintenance can
cause property damage, injury, or death.
Read the installation, operating, and
maintenance instructions thoroughly
before installing or servicing this
equipment.
For Your Safety
Do not store or use gasoline or other
flammable vapors or liquids in the vicinity
of this or any other appliance.
MODEL: mST-12 COVERING:
mInstallation
mOperation
mService & Parts

i
TABLE OF CONTENTS
PARAGRAPH
SECTION 1 INTRODUCTION
1.1Description ............................................
1.2Basic Functioning .................................
1.3Service ..................................................
SECTION 2 INSTALLATION
2.1Assembly ..............................................
2.2Setting in Place .....................................
2.3Mechanical Connections ......................
2.4W ater Connections ...............................
2.5Installation Check-Out ..........................
2.5.1Initial Control Settings ...........................
2.5.2Cooker Check-Out ................................
2.5.3Shut-Down Procedure ..........................
2.6Reversing the Doors .............................
SECTION 3 OPERATION
3.1Operating Controls & Indicators ...........
3.2Operating Procedures ..........................
3.2.1Steam Source Operation ......................
3.2.2Preheating ............................................
3.2.3Cooking ................................................
3.2.4Shut-Down Procedure ..........................
3.3Cleaning ...............................................
3.4Drainage ...............................................
3.4.1Cooking Compartment Drainage ..........
3.4.2Drip/Spill Trough Drainage ...................
3.5T est Kitchen Bulletin .............................
SECTION 4 PRINCIPLES OF OPERATION
4.1General .................................................
4.2Plumbing Circuits ..................................
4.2.1Steam Inlet Line ....................................
4.2.2Steam Exhaust & Drain Lines ...............
4.2.3Steam Exhaust Condensing System ....
4.3Electrica Circuits ...................................
4.3.1Control Circuit Components .................
4.3.1.160 MinuteTimer ....................................
4.3.1.2Indicator Lights .....................................
4.3.1.3Buzzer ..................................................
4.3.1.4Door Interlock Switch ............................
4.3.1.5Thermostatic Switch .............................
SECTION 5 TROUBLE-SHOOTING
5.1General .................................................
5.2T rouble-Shooting ..................................
5.3Electrical Fault Isolation ........................
5.4Elec Trouble-Shooting Procedures .......
5.4.1Incoming Power ....................................
5.4.2Electrical Inspection ..............................
5.4.360 Minute Timer ....................................
5.4.3.1Timer Contacts .....................................
5.4.3.2Timer Motor ..........................................
5.4.4Door Interlock Switch ............................
5.4.5Steam Solenoid V alves .........................
5.4.6Indicator Lights .....................................
5.4.7Cooking Compartment Thermostat
Switch ...................................................
PARAGRAPH
5.4.8Buzzer ..................................................
5.4.9Cold W ater Condener Circuit ................
5.4.10Wiring ...................................................
SECTION 6 MAINTENANCE
6.1General .................................................
6.2Preventive Maintenance .......................
6.2.1Cooking Compartment Cleaning ..........
6.3Repair & Replacement .........................
6.3.1Door Latch Tension Adjustment ............
6.3.2Door Handle Tension Adjustment .........
6.3.3Door Gasket Replacement ...................
6.3.4Exterior Panel Removal ........................
6.3.5Steam & W ater Solenoid Valve
Replacement ........................................
SECTION 7 ILLUSTRATED PARTS LIST
7.1General .................................................
7.2Ordering Information .............................
7.3Index of Illustrated Parts List ................
7.4Illustrated Parts List ..............................
LIST OF TABLES
TABLE
SECTION 3 OPERATION
3-1Controls & Indicators ............................
SECTION 5 TROUBLE-SHOOTING
5-1General Trouble-Shooting Guide ..........
5-2Electrically Fault Isolation Guide ..........
LIST OF ILLUSTRATIONS
FIGURE
SECTION 2 INSTALLATION
2-1T ypical Door Layout ..............................
SECTION 3 OPERATION
3-1Controls & Indicators ............................
SECTION 4 PRINCIPLES OF OPERATION
4-1Pictorial Diagram -
Steam & W ater Circuits ........................
SECTION 5 TROUBLE-SHOOTING
5-1Wiring Diagram, ST -12 .........................
5-2Schematic Diagram, ST -12 ...................
SECTION 7 ILLUSTRATED PARTS LIST
7-1Cabinet Assembly .................................
7-2Door Assembly .....................................
7-3Control Panel Assembly .......................
7-4Condenser Assembly ............................
PAGE
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PAGE
5-6
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6-1
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6-1
6-1
6-1
6-2
6-2
6-2
6-2
7-1
7-1
7-1
7-2/7-6

3-3
5-1
5-2

2-3
3-2
4-2
5-4
5-7
7-3
7-4
7-5
7-6

1-1
SECTION 1 INTRODUCTION
This service and parts manual contains general information, installation instructions, principles of operation, trouble-shooting,
and maintenance information for Market Forge ST-12 Pressureless Steam Cooker. Also included is a part list in which each
replaceable part is identified and shown in an accompanying exploded view.
1.1 Description
The ST-12 is a pressureless steam cooker consisting of a
controlled compartment enclosed in a single cabinet. The
compartment is equipped with a separate three-piece door
with inner gasket plate isolated from the exterior surface.
The door latch design ensures positive sealing of the inner
door. Steam delivery and steam-condensing circuits are
both electrically controlled. The operating controls are
displayed on a single front-mounted panel that includes a
timer with an indicator light for the selection of constant
steam or 60-minute-long duration cooking.
A separate steam source is required for operation of the
Pressureless Cooker and is normally purchased with it,
please refer to the respective manual for guidance.
1.2 Basic Functioning
The Model ST-12 compartment is equipped with controls,
allowing selection of constant steam or 60-minute timer
operation. The cooker becomes operational when it is set
to constant steam, or the timer is set at the desired
cooking time and the compartment door is closed. The
indicator light comes on and the steam solenoid valve
opens, allowing steam to flow into the compartment.
When steam flowing inside the compartment has raised
the interior temperature to 195°F, the contacts of a
thermostatic switch automatically close, completing the
circuit to the timer motor and starting the selected cooking
time period. At the end of the set interval, timer contacts
switch to shut off the cooking operation and sound a signal
buzzer. The buzzer is silenced by returning the timer dial
to the OFF position.
In the constant steam mode, operation will be continuous.
When steam and condensate is emitted from the
compartment it is directed through a drain screen inside
the compartment into the cooker drain line. A cold water
solenoid valve connected into the compartment drain line
is automatically actuated by a thermostatic switch in the
cooking compartment drain line to condense the steam to
water prior to discharge into the drain.
1.3 Service
Required service, both preventive and corrective, is
explained in Section 6. Should repairs be required, a
network of authorized service agencies is available to
assist with prompt service. A current Directory of
Authorized Service Agencies may be obtained by
contacting:
Product Service Department
Market Forge Industries Inc.
35 Garvey Street lEverett lMA l02149
Tel: [phone] lFax: [phone]
Fax: (Outside MA) 1-800-227-2659
E-Mail: [email protected] lWebsite: http://www.mfii.com
The model and serial number must be referenced when
corresponding with Market Forge service personnel. The
data plate containing the serial number pertaining to the
equipment is located on the top front trim of the cabinet
base and also on the top panel of the steamer.

2-1
SECTION 2 INSTALLATION
2.1 Assembly
The Pressureless Cooker is factory-mounted on a cabinet
base containing either a steam boiler or direct steam
connection controls for the cooker. The assembled unit is
shipped bolted to a skid, with cabinet feet in a separate
container. Steps required for assembly are as follows:
1. Remove the four bolts that fasten the equipment frame
to the skid.
2. Install feet in threaded mounting locations of the cabinet
frame.
3. Mount the two pan support racks in brackets and studs
inside cooking compartment.
4. Attach panels to lower cabinet. Detailed instructions are
enclosed with the panels.
5. Attach the drip trough on studs located on the face of
the unit.
2.2 Setting in Place
Level the unit in final location by turning the adjustable
feet. Using the cabinet top as a reference, obtain level
adjustment left-to-right and front-to-back.
2.3 Mechanical Connections
Since the Pressureless Cooker is interconnected at the
factory to the steam boiler or direct steam plumbing, no
field connections to the cooker are required. All electrical
and plumbing connections are routed to the steam boiler
cabinet through the 6-inch-high space between the floor
and the bottom edge of the cabinet frame. Connection
locations for the cooker mounted on steam boilers of
electric, gas, and steam coil utility and direct-connected
steam are shown in separate installation instructions for
each.
2.4 Water Connections
Before connecting water to this unit, have water supply
analyzed to make sure that hardness is no grater than
2.0 grains per gallon and pH level is within the range of
7.0–8.5. Water that fails to meet these standards should
be treated by the installation of a water conditioner.
2.5 Installation Check-Out
Check-out procedures for the cooker mounted on steam
boilers of electric, gas, and steam coil or direct-connected
steam are given in separate installation instructions for
each. Procedures for the cooker only are included in
Subsection 2.5.2.
If the cooker fails to perform as described, consult Table 5-
1 of the Trouble-Shooting Guide for corrective action. If
difficulty arises with the boiler, reference the separate
service and parts manual for that equipment.
Before making this check-out, the operator must be
thoroughly familiar with the operating procedures in
Section 3 and with the function of each control described
in Table 3-1. Reference Figure 3-1 for identification of
controls required in the following procedures.
2.5.1 Initial Control Settings
Before beginning the start-up procedures for the cooker,
the instruction plate and service manual for the steam
boiler must be consulted and all start-up procedures
completed to supply 15 PSI steam to the steam inlet line
for the cooker.
1. All steam boiler controls are in the operating mode and
15 PSI steam is applied to the cooker inlet plumbing.
2. Cooker timer for the compartment (Figure 3-1) is in the
OFF position.
3. Cooker compartment is empty of all information
materials, pan supports are mounted in place, and door
is open.
2.5.2 Cooker Check-Out
The cooker check-out procedures are as follows:
1. With the door open set timer to about the “4-minute”
position. Observe that indicator light is off and steam
does not enter compartment.
2. Close cooker compartment door. Observe that indicator
light turns on, and steam can be heard rushing into the
compartment simultaneously with the door closing.
3. Observe the boiler drain line for passage of steam into
the open floor drain. Correct steam condenser operation
is evidenced by presence of water flowing from the
drain line.
4. Observe cooker operation for several minutes. Opera-
tion is correct if timer dials begin to rotate after a short
delay period required for preheating. After the delay
period plus the “4-minute” initial setting, the timer dials
will return to the “0-Minute” position, at which a buzzer
sounds. The buzzer is silenced by turning the dial to the
OFF position.
EQUIPMENT FAILURE CAUSED BY INADEQUATE
WATER QUALITY IS NOT COVERED UNDER
WARRANTY!
CAUTION
PVC or CPVC are not acceptable materials for drains.

2-2
SECTION 2 INSTALLATION
2.5.3 Shut-Down Procedure
No shut-down procedure is required for the Pressureless
Cooker except to check that the timer dial is in the OFF
position and the compartment door are open. Consult the
steam boiler instruction plate and complete the shut-down
procedures for the boiler.
2.6 Reversing the Doors
The Pressureless Steam Cooker has a reversible cooking
compartment door. This section contains instructions for
reversing this door.
1. Turn off power to the unit.
2. Open the cooking compartment door
3. Remove the two screws that attach the top hinge to the
front of the unit.
4. Slide the door upwards, off the bottom hinge.
5. Remove the two screws that attach the bottom hinge to
the front of the units.
6. Remove the right and left side panels by unscrewing the
1 screw on each panel and sliding the panel down.
7. Remove the door interlock assembly by unscrewing the
two nuts that hold it in place (assembly is attached to
the screws in the top right hinge mounting holes, see
fig. 2-1).
8. Remove the four screws in the right side hinge
mounting holes and install them in the left side hinge
mounting holes (where the hinges were originally
mounted).
9. Using the nuts removed in step #6, reinstall the door
interlock assembly onto the 2 screws in the lower left
hinge mounting holes (see fig. 2-1) with by moving the
assembly over the cooking cavity to the other side of the
unit. Rotate the door interlock assembly 180° for
installation, so that the switch is now facing up.
10. Reinstall the top hinge and screws into the right lower
hinge mounting holes. Rotate the hinge 180° for
installa- tion, so that the pin which the door rides on is
now facing up. The hinge must be rotated because it
will now function as the bottom hinge. DO NOT
COMPLETELY TIGHTEN THE HINGE MOUNTING
SCREWS YET. These will be used later for adjusting
the door.
11. Remove the door latch assembly from the face of the
unit. The 2 nuts mounting the door latch are located
behind the face of the unit and must be accessed
where the right side panel was removed.
12. Remove the two white hole plugs from the left door
latch mounting holes, and insert them into the right
door latch mounting holes (where the door latch
assembly was originally mounted).
13. Rotate the door latch assembly 180°, and install into
the left door latch mounting holes.
14. To adjust the tension of the door latch, tighten both
nuts down until the springs are fully compressed, then
back each nut off 1 1/2 turn.
15. Rotate the door 180° for mounting.
16. Slide the remaining hinge into the top door bearing.
17. Slide the door and hinge assembly down onto the
hinge which you have already mounted to the front of
the unit. Use the two screws to mount the top hinge
into the right upper hinge mounting holes. DO NOT
COMPLETELY TIGHTEN THE HINGE MOUNTING
SCREWS YET.
18. Slowly push the cooking compartment door closed
until it is latched.
19. The cooking compartment door can now be raised,
lowered, and/or rotated into position by bumping it with
the palm of your hand or by using a small rubber
mallet.
20. First, check the alignment at the front of the door by
making sure that the striker in the door is centered with
the latch mechanism on the front of the unit.
21. Square the door to the unit by raising or lowering the
hinge side of the door, keeping the latch centered with
the striker.
22. Visually inspect the door. Be sure that the door is
square to the unit, the striker is centered with the latch,
and the gasket is in contact with the entire lip of the
cooking compartment.
23. Gently open the cooking compartment door, taking
care not to move it out of position.
24. Tighten all 4 door hinge bracket mounting screws.
25. Close and visually inspect the door again, as
described in step 22.
26. Reinstall the left and right side panels, using the
screws for each panel.
NOTE:
Each stud on the latch assembly should have a plastic
washer, a spring, a plastic washer and a Nyloc type nut.

2-3
SECTION 2 INSTALLATION
TOP LEFT HINGE MOUNTING HOLES
LEFT DOOR LATCH MOUNTING HOLES
INTERLOCK ASSEMBLY POSITION WHEN DOOR IS REVERSED
LOWER LEFT HINGE MOUNTING HOLES
TOP RIGHT HINGE MOUNTING HOLES
INTERLOCK ASSEMBLY ORIGINAL POSITION
DOOR LATCH ASSEMBLY ORIGINAL POSITION
LOWER RIGHT HINGE MOUNTING HOLES
Figure 2-1 Typical Door Layout

3-1
SECTION 3 OPERATION
3.1 Operating Controls and Indicators
The controls and indicators required to operate the
Pressureless Steam Cooker are listed in Table 3-1,
together with a short functional description of each.
Figure 3-1 shows the physical location of each control and
indicator.
3.2 Operating Procedures
The ST-12 Pressureless Steam Cooker defrosts frozen
foods and cooks fresh and defrosted foods. The cooking
compartment permits selection of continuous (constant
steam) cooking or timed (0–60 minutes) cooking.
Instructions for operation are included in this section.
Consult Test Kitchen Bulletin for detailed cooking
information.
3.2.1 Steam Source Operation
The Pressureless Cooker is supplied mounted on a
cabinet containing either a steam boiler or controls for
direct-connected steam. Manual controls are accessed by
opening the cabinet door. The start-up procedure for the
steam source is completed once before each daily
operating period of the cooker. (For steam boilers, see
instruction plate.)
3.2.2 Preheating
Before each initial operation of the cooker, and at any
other time when the cooking compartment is cold, a 1-
minute preheating period is required. To preheat the
cooker, put steam source into operation and proceed as
follows:
1. Close cooking compartment door.
2. Set 60-Minute Timer Dial (1) to “4-minute” setting.
3. Turn off buzzer, which sounds to indicate cooking is
complete, by setting the Timer Dial (1) to OFF position.
3.2.3 Cooking
Before loading the cooker, be sure compartment is hot.
See Subsection 3.2.2 for preheating instructions.
1. Slide pans of food into cooking compartment pan
supports.
2. Close cooking compartment door.
3. Set timer cooking time:
a. constant steam—for continuous cooking
b. 60-minute timer—for timed cooking.
4. Set appropriate timer to the required cooking time (see
pages 3.3 to 3.6).
5. Turn off buzzer, which sounds to indicate cooking is
complete, by setting timer dial (1) to the OFF position.
6. Open door sightly at first letting most of the steam out of
the compartment and then fully open the door.
7. Unload by sliding pans of food from pan supports,
taking care to avoid hitting compartment opening.
3.2.4 Shut-Down Procedure
No shut-down procedure is required for the cooker except
to check the timer dial (1) are in the OFF position and that
the compartment door is open. When all cooking has been
completed for the day, the steam source must be shut off.
(For steam boilers, see instruction plate.)
3.3 Cleaning
After each period of daily operation (more frequently as
required to maintain cleanliness), the cooker should be
thoroughly cleaned by completing the following steps:
1. Remove left, right & center pan supports, and drain
screen by lifting up and off mounting studs. Wash with a
mild detergent. Rinse and set aside for reassembly.
2. Wash cooking compartment interior using a mild
detergent and water. Rinse and dry thoroughly.
3. Replace pan supports, and drain screen in compartment
and leave door slightly ajar.
3.4 Drainage
3.4.1 Cooking Compartment Drainage
The bottom of the cooking compartment is angled slightly
toward the rear of the unit. This assures that any
condensate build-up or spills will be directed toward the
drain hole, which is located at the rear bottom center of the
cooking compartment. Any liquid exiting the cooking
compartment runs down the cooking compartment drain
tube and into the drain line.
NOTE:
Total elapsed preheating time equals the timer
setting plus a short delay period needed to active a
thermostatic switch included in the controls.
CAUTION
When the unit is not in use, leave the cooking
compartment door slightly ajar to prolong the life of
the door gasket.

3-2
SECTION 3 OPERATION
PLUS - 12
STEAM
UPPER COMPARTMENT
&
LOWER COMPARTMENT
STEAM
LOWER COMPARTMENT
&
KETTLE
TIMER
TIMED
STEAM
OFF
CONSTANT
STEAM
O
oOFF
12
3
456
789
0
START
STOP
CLEAR
3
4
5
CONVECTION
STEAM
COOKER
STEAM
UPPER COMPARTMENT
&
LOWER COMPARTMENT
STEAM
LOWER COMPARTMENT
&
KETTLE
OFF
O
oOFF
5
2
1
MANUAL OPTION
DIGITAL OPTION
0
S
T
E
A
M
5
10
15
20
25
30
35
40
45
50
55
60
C
O
N
S
T
A
N
T
O
F
F
Figure 3-1 Controls & Indicators
3.4.2 Drip/Spill Trough Drainage
The ST-12 Pressureless Steam Cooker has a drip/spill
trough below the cooking compartment door. It will catch
any condensate gathering on the front of the unit when the
door is opened.
TABLE 3-1
CONTROLS & INDICATORS
(See Figure 3-1)
REF. NUMBER
1

2

3

4
DESCRIPTION
Timer/Constant Steam

Indicator Light
Digital Timer
Mode Switch
FUNCTION
Controls cooking up to
60 Minutes or uses
constant operation.
Indicates cooker is in
operation.
Control cooking up to
99 minutes or constant.
Constant Steam/Timer

3-3
SECTION 3 OPERATION
TEST KITCHEN BULLETIN
Model ST-12 Pressureless Cooker
Facts On Parade
3.5 TEST KITCHEN BULLETIN
1. Frozen vegetables should always be cooked in perforated 12” x 20” x 2 1/2” (1/1 65mm) pans.
2. Frozen entrees should be underlined with a perforated pan for best results. If they are defrosted first, the heating
time will be decreased.
3. Fresh foods may also be cooked in this unit. Vegetables and other foods where the stock is not to be retained
should be cooked in perforated 12” x 20” x 2 1/2” (1/1 65mm) pans for the most nutritious results.
4. There is a thermostatic time delay built into this unit which adapts the unit to the proper cooking time. This means
that the total time will usually be longer than the time setting.
5. There is a safety interlock switch on the door which shuts off the steam each time the door is opened if the unit is in
the cooking cycle.
6. Compartments may be filled and timer set simultaneously.
7. Sheet pans will fit in compartment with the center rack removed.
8. All foods, except cakes and pastry, can be cooked in a steam cooking unit.
9. Steam cooked meals have greater nutritional value since they retain most of their vitamins and minerals.
10. Because foods are cooked faster by the higher temperatures of steam cooking, they can be prepared closer to
serving time, insuring maximum freshness.
11. Steam cooked foods have a higher percent yield more portions per dollar spent.
12. Food may be served from the same pan in which it is steam cooked, thus reducing food breakage since there is no
extra handling or transferring of food from cooking pans to serving pans. It also reduces pot washing tasks.
13. Some important advantages of steam cooking are labor saving, reduced operating costs, space saving, and the
lifting of heavy stock pots is eliminated.
14. Rice and spaghetti products, if thoroughly wet at the start of the cooking process, are very easily prepared.
15. Food such as potatoes, poultry, seafood, and some meats may be blanched in the steam cooker, thus reducing the
total cooking time and grease absorption.
16. Fuel is used only when the steam cooking unit is in operation.
17. The steam cooker will loosen foods burned on pans making washing easier.
18. Solid pans are recommended when liquid is to be retained and perforated pans when the liquid is not to be retained.
19. Eggs may be cooked out of the shell if they are to be chopped which eliminates peeling after steaming.
20. The steam cooker can be opened during the cooking period to add or remove items. If any time is lost, an
adjustment may be made on the timer.
21. Steam cooking information, including recommended pan size and type, weight per pan, cooking times and pan
yields are given on the following pages of this manual.