948RX
SERVICE MANUAL
HEAVY DUTY GAS GRIDDLES
MODELS
924RX MSA24
936RX MSA36
948RX MSA48
960RX MSA60
972RX MSA72
This Manual is prepared for the use of trained Vulcan Service
Technicians and should not be used by those not properly qualified.
This manual is not intended to be all encompassing. If you have not
attended a Vulcan Service School for this product, you should read,
in its entirety, the repair procedure you wish to perform to
determine if you have the necessary tools, instruments and skills
required to perform the procedure. Procedures for which you do not
have the necessary tools, instruments and skills should be
performed by a trained Vulcan Service Technician.
The reproduction, transfer, sale or other use of this Manual, without
the express written consent of Vulcan, is prohibited.
This manual has been provided to you by ITW Food Equipment
Group LLC ("ITW FEG") without charge and remains the property
of ITW FEG, and by accepting this manual you agree that you will
return it to ITW FEG promptly upon its request for such return at
any time in the future.
For additional information on Vulcan-Hart Company or to locate an authorized parts
and service provider in your area, visit our website at www.vu lcanhart.com.
A product of VULCAN-HART LOUISVILLE, KY 40201-0696
F25383 (510)
GENERAL
TABLE OF CONTENTS
GENERAL ................................................................................3
Introduction ............................................................................3
Installation ............................................................................ 3
Operation .............................................................................3
Cleaning .............................................................................. 3
Specifications ..........................................................................3
Tools.................................................................................4
Component Location ....................................................................4
REMOVAL AND REPLACEMENT OF PARTS ....................................................5
Covers and Panels ......................................................................5
Front Panel ........................................................................5
Back Panel ........................................................................5
Momentary Power Switch (900rx) ..........................................................5
Electric Igniter (900rx) ...................................................................6
®
BASO
Thermostat Valve Assembly...............................................................6
Burner................................................................................8
Pilot, Thermocouple Assembly ............................................................. 8
SERVICE PROCEDURES AND ADJUSTMENTS..................................................9
Calibration ............................................................................ 9
Pilot Adjustment .......................................................................10
Gas Pressure Measurement..............................................................10
Gas Pressure Regulator Adjustment .......................................................10
Burner Adjustment .....................................................................11
Thermocouple Test .....................................................................12
Safety Valve.....................................................................6
ELECTRICAL OPERATION.................................................................. 13
Electrical Diagram ..................................................................... 13
TROUBLESHOOTING......................................................................15
© VULCAN 2010
F25383 (510)
Page 2 of 16
GENERAL
GENERAL
The griddle and its parts are hot. Use care when operating, cleaning or servicing the griddle.
INTRODUCTION
This Service Manual covers specific service
information related to the models listed on the front
cover and built after March 2010.
Procedures in this manual will apply to all 900RX
models unless specified. No procedure in this
manual will require the removal or raising of the
griddle plate. Pictures and illustrations can be of any
model unless the picture or illustration needs to be
model specific.
MSA griddles have a standing pilot that must be lit
manually. One pilot services two burners via a flame
tube between the burners. The 900RX utilizes a
spark ignition system that has a 'momentarily on'
switch - that means the switch must be held down for
sparking to take place, and it ceases sparking when
released.
The MSA and 900RX have BASO
valves that must be pressed to allow gas to feed the
pilot burner. For the 900RX, the pilot buttons must be
pressed at the same time the power switch is
pressed in order to light the pilot.
®
pilot safety
INSTALLATION
Generally, installations are made by the dealer or
contracted by the dealer or owner. Detailed
installation instructions are included in the
Installation and Operation Manual that is sent with
each unit. However, it should be noted that an
improperly installed unit, especially an unlevel unit
can lead to premature electrical component failures.
A unit that is higher in the front will cause the flue
gases to vent improperly and gather in the front near
the electrical components. All models must be
installed with an externally mounted regulator.
monitored by thermocouples and pilot safety valves.
If the pilot goes out, the safety valve will shut-off the
gas supply to the pilot and main burners. In the event
of a failure of the electronic ignition system, it is
possible to ignite the pilots with an outside source
(such as a lit taper). You will have to reach under the
front of the unit and through the pilot cutout to ignite
the pilots while again depressing the corresponding
red button.
CLEANING
Detailed cleaning procedures are included in the
Installation & Operation manual sent with each unit.
SPECIFICATIONS
Stainless steel front, sides and front top ledge. Fully
welded stainless and aluminized steel body frame.
11" low profile cooking height on 4" legs. 1" thick
polished steel griddle plate with 12 gage, 4" stainless
steel back and tapered side splashes. Grease chute
is fully welded to stop grease migration.
One 27,000 BTU/hr. “U” shaped aluminized steel
burner and mechanical snap action thermostat for
each 12" of griddle width. Chrome thermostat knob
guards. Temperature adjusts from 200° to 550° F.
One pilot safety for every two burners. Manual
shut-off valve. 3½" wide stainless steel grease
trough. 120V 50/60Hz 1 Amp single phase electric
ignition circuit. Plug type is NEMA 5-15 USA. ¾"
rear gas connection and gas pressure regulator.
A gas pressure regulator supplied with the unit must
be installed.
Check and set the gas pressure after the regulator is
installed.
Manifold pressure should be:
OPERATION
Detailed operation instructions are included in the
Installation & Operation Manual sent with each unit
and are also available at
WWW.VULCANHART.COM.
The 900RX models feature an electric ignition
system that is controlled by a momentary power
switch. The power switch turns the electric ignition
system off and on only and will only supply power to
the igniters when held down in the ON position. The
burners and pilots will continue to work with the
power switch in the OFF position until the gas supply
to the unit is cut off or the griddle gas shut-off valve
is turned to the OFF position. The pilots are
Natural Gas 4.0" W.C.
Propane Gas 10.0" W.C.
Incoming pressure should be 5-9" W.C. for Natural
Gas and 11.0" W.C. for Propane Gas.
Incoming pressure should not exceed 14.0" W.C.
F25383 (510)Page 3 of 16
TOOLS
• Standard set of hand tools.
• VOM with A/C current tester (any quality VOM
with a sensitivity of at least 20,000 ohms per
volt can be used).
• Temperature tester (thermocouple type).
• U-Tube or Digital Manometer.
• Thread sealant suitable for use with natural or
propane gas.
• Aluminum Foil Tape - McMaster Carr Part
No.7631421 or equivalent.
• Adapter to test thermocouple, Johnstone Supply
Part No. H23-226 or equivalent.
GENERAL
924RX SHOWN
1. Burner assembly
2. Electric igniter (RX only)
3. Thermostat
4. Orifice
5. Thermostat capillary tube
6. Pilot, igniter (RX only) and thermocouple
®
7. BASO
pilot safety valve
COMPONENT LOCATION
924RX SHOWN
1. Pilot electric ignition system control switch (RX
only)
2. Power cord (RX only)
3. Thermostat
4. Gas shut off valve (RX only)
®
5. BASO
pilot safety valve
8. Pilot adjustment valve
6. Pilot flame adjustment
F25383 (510)
Page 4 of 16
REMOVAL AND REPLACEMENT OF PARTS
REMOVAL AND REPLACEMENT OF PARTS
COVERS AND PANELS
Front Panel
1. Turn all thermostats to off position, loosen set
screw securing thermostat knobs and pull off
knobs.
Back Panel
NOTE: It will be necessary to remove the back panel
when changing a burner or to remove excessive
grease build up from flue area.
1. Disconnect gas supply at griddle.
2. Remove screws securing back panel to griddle.
3. Install in reverse order.
MOMENTARY POWER SWITCH
(900RX)
NOT IN OFF POSITION FOR VIEW
2. Remove screws securing front panel to griddle.
3. Pull front panel forward and lay aside. If
servicing a 900RX lay front panel face down in
front of unit.
4. Install in reverse order.
NOTE: Before installing front panel, check that lineof-sight through the front panel to see both pilot
burners and griddle burners. Move any flexible gas
tubing, or capillary tubing that may obstruct the sight
holes.
1. Remove FRONT PANEL.
2. Label and disconnect wires from power switch.
3. Squeeze switch retainers and slide switch out
through front of panel.
4. Install in reverse order.
F25383 (510)Page 5 of 16
REMOVAL AND REPLACEMENT OF PARTS
ELECTRIC IGNITER (900RX)
1. Remove FRONT PANEL.
2. Push tab to release igniter from frame and pull
out of unit.
2. Measure distance between manifold pipe and
valve for reassembly later.
NOTE: Ignition wires must be routed in front of
valves as shown to prevent them from touching hot
heat shield.
3. Disconnect all gas lines and thermocouple from
valve.
4. Remove valve from unit.
5. Transfer fittings from old valve to new valve.
Use thread sealant on assembly.
3. Label and disconnect wires from electric igniter.
4. Install in reverse order.
BASO® SAFETY VALVE
1. Remove FRONT PANEL.
6. Install new valve to same measurement as in
step 2.
7. Continue to install in reverse order.
THERMOSTAT VALVE
ASSEMBLY
1. Remove FRONT PANEL.
2. Disconnect gas line.
F25383 (510) Page 6 of 16
REMOVAL AND REPLACEMENT OF PARTS
3. Remove screws securing thermostat mounting
bracket to frame.
4. Pull capillary tube out from underneath griddle
plate.
5. Transfer fittings from old thermostat to new
thermostat. Use thread sealant.
6. Transfer thermostat mounting bracket to new
thermostat.
10. Carefully insert orifice into burner and secure
thermostat mounting bracket to frame.
11. Inlet to burner must be straight. Adjust thread
on orifice and/or extension to close gap
between orifice and burner to 1/16".
7. Remove insulator sleeve from old capillary tube
and install on new thermostat.
8. Secure end of insulator sleeve to thick end of
capillary tube with metal tape as shown.
9. Slide capillary tube all the way into slot
underneath griddle plate until it is fully seated.
12. Continue to install in reverse order.
F25383 (510)Page 7 of 16
REMOVAL AND REPLACEMENT OF PARTS
BURNER
1. Remove FRONT PANEL and REAR PANEL.
2. Disconnect gas supply at griddle.
3. Remove screw securing burner to wall.
PILOT, THERMOCOUPLE
ASSEMBLY
1. Remove FRONT PANEL.
2. From underneath the front of the griddle,
remove screw securing pilot assembly bracket.
4. At rear of unit, pull burner enough to disengage
burner pin from frame and pull burner out.
5. Install in reverse order.
6. Adjust as outlined in BURNER ADJUSTMENT.
VIEW FROM REAR OF UNIT TO SEE PARTS
3. Carefully lift to disengage bracket from slot and
work assembly down to access parts.
4. Service assembly as required and assemble in
reverse order being sure bracket is seated in
slot for alignment.
F25383 (510)
Page 8 of 16
SERVICE PROCEDURES AND ADJUSTMENTS
SERVICE PROCEDURES AND ADJUSTMENTS
CALIBRATION
Level
The griddle must be level (side-to-side and
front-to-back) during operation to ensure proper
performance. Improper leveling can result in uneven
temperature distribution, cold spots, and possibly
damage electrical components.
1. Place a level on the griddle.
2. Adjust legs by turning the bullet feet at the
bottom of each leg. Using pliers or a crescent
wrench, turn the feet counter-clockwise to
increase height, and clockwise to decrease
height until leveling is achieved. Do not extend
the legs more than 1-¾”.
Calibrate
1. Each thermostat controls a 12” zone of the
griddle. Using a Surface Probe temperature
measurement device, observe the temperatures
at the center points of the cooking zones. These
points are located by starting 6” from the side
splash (left or right) and every 12” across the
width of the griddle, with all points located 12”
back from the front edge of the griddle plate.
NOTE: Use of infrared thermometers is not
recommended. These devices are highly sensitive to
surface color (clean or dirty), angle of reading and
distance from the unit.
2. Set thermostats to 350°F and allow to stabilize.
3. Record the temperature tester readouts for
each zone for 3 cycles.
Temperature
Tester turn-off
deg F
____
____
____
4. Calculate total average temperature for that
zone.
5. The temperature should be 350°F ±15°F. If not,
continue to next step.
6. Carefully loosen the knob set screw. DO NOT
allow the knob to turn. Carefully remove the
knob from the thermostat shaft, exposing the
temperature dial.
Temperature
Tester turn-on
deg F
____
____
____
Turn-Off +
Turn-On divide
by 2 = average
____
____
____
Total averages
divide by 3
____ deg F
7. Loosen screws on the temperature dial and
adjust it so that the temperature indicated by the
knob arrow matches the griddle plate
temperature reading. Knob will have to be
carefully placed back on the shaft to verify
adjustment.
F25383 (510)Page 9 of 16
SERVICE PROCEDURES AND ADJUSTMENTS
GAS PRESSURE
MEASUREMENT
1. Turn the gas supply off at a manual shutoff
valve.
2. Remove the control panel.
3. Remove the pressure tap plug and attach
manometer.
Never adjust the screw in the center of the
thermostat shaft. This will ruin the factory calibration;
the thermostat will no longer operate properly and
will need to be replaced.
8. Once calibration is achieved, tighten the
temperature dial screws and knob set screws.
9. Repeat steps 3 thru 8 for each zone.
PILOT ADJUSTMENT
4. Turn gas back on.
5. Light pilot(s).
6. Turn all thermostats on to the maximum setting
so that all burners are on.
7. Turn all the equipment on the same supply line
on.
8. Check gas pressure.
9. Gas pressure should read 4” W.C. for natural
and 10” W.C. for propane gas. If not correct,
refer to GAS REGULATOR ADJUSTMENT.
10. Turn gas supply off, disconnect manometer and
reinstall pressure tap plug.
924RX SHOWN
Using a flathead screwdriver, turn the slotted pilot
adjustment screw clockwise to decrease the flame,
and counterclockwise to increase the flame.
F25383 (510)
GAS PRESSURE REGULATOR
ADJUSTMENT
A gas pressure regulator is supplied with the griddle
and must be installed as close to the griddle on the
gas supply line as possible. Make sure that the arrow
on the underside of the regulator is oriented in the
direction of gas flow to the griddle and the regulator
is positioned with the vent plug and adjustment
screw upright. Check that vent plug is not clogged by
grease and debris.
Check and set the gas pressure after the regulator is
installed. The pressure should be set for 4” water
column (W.C.) for natural gas and 10” W.C. for
propane gas while all burners are on.
Page 10 of 16
SERVICE PROCEDURES AND ADJUSTMENTS
The supply pressure (upstream of the regulator)
should be 7-9” W.C. for natural gas and 11-12” W.C.
for propane gas. At no time should the griddle be
connected to supply pressure greater than ½ psig
(3.45 kPa) or 14” W.C.
Graphic shows pressure plug location.
NOTE: MSA models are in same locations. There are no shut off valves.
BURNER ADJUSTMENT
For efficient burner operation, it is important that a
proper balance of gas volume and primary air supply
is maintained to give complete combustion.
Insufficient air supply results in a yellow streaming
flame. Primary air supply is controlled by the air
shutter on the front of the burner venturi. Loosen the
screw on the venturi and adjust the air shutter to just
eliminate yellow tips on the burner flames. Lock the
air shutter in place in place by tightening the screw.
Repeat this procedure as necessary with all burners.
F25383 (510)Page 11 of 16
SERVICE PROCEDURES AND ADJUSTMENTS
THERMOCOUPLE TEST
1. Unscrew thermocouple fitting from safety valve.
2. Install thermocouple test adapter finger tight
plus a quarter turn.
3. Install thermocouple into test adapter finger tight
plus a quarter turn.
8. Verify thermocouple output voltage.
A. If 25 - 35 millivolts is measured, the
thermocouple is functioning properly.
B. If less than 17 millivolts is measured,
install a replacement thermocouple.
9. Remove test adapter.
NOTE: Over tightening can cause thermocouple tip
to short out.
4.
Set VOM to DC millivolt scale and connect (+)
meter lead to pin on thermocouple adapter and
(-) meter lead to thermocouple.
5. Light pilot flame.
6. Verify that
flame. Adjust pilot valve to allow more gas flow if
necessary.
7. With thermostat off, allow pilot to burn for 3-4
minutes to stabilize voltage output from
thermocouple.
thermocouple is sufficiently immersed in
F25383 (510) Page 12 of 16
ELECTRICAL OPERATION
ELECTRICAL DIAGRAM
ELECTRICAL OPERATION
F25383 (510)Page 13 of 16
ELECTRICAL OPERATION
F25383 (510) Page 14 of 16
TROUBLESHOOTING
TROUBLESHOOTING
SYMPTOMS POSSIBLE CAUSES
No spark to ignite pilot gas. 1. Power cord unplugged.
2. Igniter switch malfunction.
3. Shorted electrode on ignitor.
4. Ignitor cable malfunction.
5. Interconnecting wiring malfunction.
6. Electric Igniter Module malfunction.
Sparks but gas does not ignite. 1. Service gas valve closed.
2. Gas supply not purged of air. Depress pilot safety button until
air is purged.
3. Gas supply off or insufficient gas pressure.
4. Adjust pilot valve to allow more gas flow.
5. Safety valve malfunction.
Gas pilot ignites but will not maintain flame. 1. Air blowing pilot out. Prevent air flow from affecting unit.
2. Gas supply not purged of air. Depress pilot safety button until
air is purged.
3. Adjust pilot valve to allow more gas flow.
4. Thermocouple not sufficiently immersed in flame. Adjust
accordingly.
5. Thermocouple malfunction. Refer to THERMOCOUPLE TEST.
6. Obstructed pilot orifice.
7. Insufficient gas pressure.
8. Safety valve malfunction.
Gas burners ignite but will not maintain flame. 1. Gas pressure incorrect or fluctuating.
2. Obstructed flue.
3. Gas orifice obstructed, improperly aligned / spaced, or
incorrect.
4. Burner malfunction.
One or more burners have lower flame level than
the others.
One burner has a delayed ignition; a several
second lapse when the burner actually lights.
Excessive or low heat. 1. Gas shut off valve not completely open.
Heat does not come on when the thermostat
is turned on.
1. Check gas pressure.
2. External air flow or vent hood problems may agitate affected
burners.
3. Gas orifice obstructed, improperly aligned / spaced, or
incorrect.
4. Adjust burner air shutter.
1. Check gas pressure.
2. Check that burner is properly seated.
3. Check that burner ignition ports, pilot flash tube and pilot burner
are all aligned.
4. Gas orifice obstructed, improperly aligned / spaced, or
incorrect.
5. Check burner shutter adjustment.
6. Check pilot flame adjustment.
2. Thermostats need calibrated. See CALIBRATION section.
3. Thermostat malfunction.
4. Gas pressure incorrect.
5. Unit's gas
6. Incorrect gas type.
7. Gas orifice obstructed or incorrect.
1. Pilot burner not lit.
2. Griddle shut-off valve not in ON position.
3. Low gas pressure.
4. Thermostat malfunction.
regulator not installed or malfunctioning.
F25383 (510)Page 15 of 16
TROUBLESHOOTING
F25383 (510) Printed in USA
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