Duke WB302-NAT User manual

This manual is Copyright 2011 Duke Manufacturing Company. All rights reserved.
Reproduction without written permission is prohibited. Duke is a registered
trademark of the Duke Manufacturing Company.
Duke Manufacturing Company
2305 N. Broadway
St. Louis, MO 63102
Phone: [phone]
Toll Free: 1-800-735-3853
Fax: [phone]
www.dukemfg.com
Please read this manual completely before attempting to
install, operate or service this equipment
Service Manual
GAS OPERATED
WETBATH
FOODWARMERS
MODELS
WB302-NAT WB302-LP
WB303-NAT WB303-LP
WB304-NAT WB304-LP
WB305-NAT WB305-LP
P/N 219218B

Gas Operated Foodwarmers
2
IMPORTANT WARNING AND SAFETY INFORMATION
WARNING
READ THIS MANUAL THOROUGHLY BEFORE OPERATING, INSTALLING OR PERFORM-
ING MAINTENANCE ON THE EQUIPMENT.
WARNING
FAILURE TO FOLLOW INSTRUCTIONS IN THIS MANUAL CAN CAUSE PROPERTY
DAMAGE, INJURY OR DEATH.
WARNING
DO NOT USE OR STORE GASOLINE OR OTHER FLAMMABLE VAPORS OR LIQUIDS
IN THE VICINITY OF THIS OR ANY OTHER APPLIANCE.
WARNING
DO NOT OPERATE THIS EQUIPMENT WITHOUT PROPERLY PLACING AND SECURING
ALL COVER AND ACCESS PANELS.
CAUTION
Observe the following:
• Provide and maintain adequate minimum clearances from all walls and combustible materials.
• Provide and maintain adequate clearance for air openings.
• Keep the equipment area free and clear of combustible material.
• Operate equipment only on the type of electricity indicated on the specication plate.
• Retain this manual for future reference.

3
Gas Operated Foodwarmers
TABLE OF CONTENTS
SPECIFICATIONS ...............................................................................................................................4
INSTALLATION ...................................................................................................................................4
Location ...............................................................................................................................4
Leveling ...............................................................................................................................4
Stabilizing ............................................................................................................................4
Gas Connection ...................................................................................................................4
MAINTENANCE ..................................................................................................................................5
Stainless Steel Care and Cleaning ......................................................................................5
Gas Regulators ....................................................................................................................5
SERVICE INFORMATION / TROUBLESHOOTING ............................................................................6
PARTS REPLACEMENT .....................................................................................................................7
Gas Valve Replacement ..............................................................................................................7
Safety Valve Replacement...........................................................................................................8
Thermocouple Replacement .......................................................................................................8
Pilot Replacement .......................................................................................................................9
Direct Burn Pilot ...................................................................................................................9
Safety Valve Pilot .................................................................................................................9
Burner Replacement ..................................................................................................................10
Direct-Burn Burner .............................................................................................................10
Safety Valve Burner ...........................................................................................................10

Gas Operated Foodwarmers
4
INSTALLATION
Location
The unit represented in this manual is intended for
indoor use only. Be sure the chosen location has
a oor strong enough to support the total weight
of the unit . Reinforce the oor if necessary to
provide for maximum loading. For the most efcient
operation, be sure to provide good air circulation
inside and out.
Figure 1.
Gas Foodwarmer
Leveling
Be sure that the units are placed on a rm, at
surface/oor. Check for cracks in ooring or tile
and avoid these areas if possible. If necessary
place support pads, properly rated for the weight
of the unit, to “bridge” uneven or cracked ooring.
Level the unit accordingly.
Stabilizing
Use the leg adjustments to insure that the unit
is solid to the oor surface at all contact points.
Insure that the unit does not “rock” when pressure
is applied to the top corners.
Gas Connection
Gas food warmers are available for natural gas
and propane. All gas connections service must be
performed by a certied plumber and must comply
with local codes.

5
Gas Operated Foodwarmers
MAINTENANCE
Stainless Steel Care and Cleaning
Stainless steel contains 70-80% iron, which will rust.
It also contains 12-30% chromium, which forms an
invisible passive lm over the steel surface and acts
as a shield against corrosion. As long as the protective
lm remains intact, the metal will not corrode.
However, if the lm is broken or contaminated,
outside elements can begin to breakdown the steel
and begin to form rust or discoloration. To prevent
rust and discoloration on stainless steel, several
important steps need to be taken.
CAUTION: Never use steel wool pads or wire
brushes or scrapers.
Avoid cleaning solutions that
contain alkaline or chloride.
Use alkaline based or non-chloride cleaning
solutions. Anything containing chloride will damage
the protective lm on stainless steel. Chlorides
are found in household and industrial cleaners
and also in hard water and salts. If a chloride or
alkaline cleaner has been used, rinse repeatedly
and dry thoroughly.
Always use only soft cloths or plastic scouring pads.
For routine cleaning, use warm soapy water. For
stubborn stains use a non-abrasive cleanser. For
heavy grease use a degreaser. For best results,
rub with the grain of the steel.
Pitting and cracking are early signs of stainless
steel breakdown. But special stainless steel
cleaners can restore and preserve the protective
lm. If signs of breakdown appear, thoroughly clean
and dry all surfaces. Begin regular application of
a high quality stainless steel cleaner according to
the manufacturer’s instructions. Again, always rub
with the grain of the steel for best results.
CAUTION: Never use an acid-based
cleanser! Be sure to clean
all food products from any
stainless surface. Many food
products contain acid, which can
deteriorate the nish. Common
foods include tomatoes, peppers
and other vegetables.
WARNING
THE GAS SUPPLY MUST BE TURNED
OFF AND DISCONNECTED AT ALL
TIMES DURING MAINTENANCE OR
REPAIR FUNCTIONS.
Gas Regulators
Figure 2.
Typical Gas Regulator
A regulator (see Figure 2) is a device for maintaining
a constant safe, operating pressure between a gas
source and a gas appliance. A regulator works
independently of supply pressure and ow.
Installation, service and repair of gas regulators
must be performed by qualified, certified
maintenance personnel.
The Vent Limiting Device is standard on the
regulators. The vent limiter limits gas levels to
within the ANSI safe standard level in the event
of a gas leak. It is absolutely necessary to provide
and maintain free airow around the vent limiter.

Gas Operated Foodwarmers
6
SYMPTOM
Cabinet too cold
Cabinet too warm
Water in bottom of unit
CAUSE
Unit won’t light
Unit won’t light
Pilot light won’t stay lit
Flame set too high
Drain hose plugged
Drain hose loose or disconnected from
drain pan
REMEDY
Turn gas on (Direct burn units)
Light pilot light
Replace thermocouple (Safety valve units)
Adjust pilot ame (Direct burn units)
Turn gas valve down
Clear drain hose
Tighten or connect drain hose.
TROUBLESHOOTING

7
Gas Operated Foodwarmers
PARTS REPLACEMENT
Gas Valve Replacement.
Figure 3.
Location of gas valves
General
The gas valve is located in front on the control
panel below each pan (see Figure 3).
1. Shut the gas supply to the unit off.
2. Remove the galvanized burner liner.
3. Remove the knob.
4. Remove the mounting screws.
5. Disconnect the burner tube from the valve.
CAUTION: Do not kink the burner tube when
moving it out of the way.
6. Remove the valve from the manifold.
7. Place gas rated thread sealer on new valve
threads.
Figure 4.
Manifold with gas valve
8. Thread the new valve onto the manifold as
shown in Figure 4. Make sure it is tight.
9. Place gas rated thread sealer on the threads
of the valve.
10. Reconnect the burner tube.
11. Perform pressure check for leaks.
12. Install the bottom cover.
13. Connect the unit to the gas supply.
14. Turn the gas on and light the pilot.
15. Replace the galvanized burner liner.

Gas Operated Foodwarmers
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Safety Valve Replacement
Figure 5.
Safety Valve
General
Safety valves are mounted between the gas control
valve and the burner (see Figure 5).
1. Shut off the gas supply.
2. Remove the galvanized burner liner.
3. Remove the screws the hold the bottom cover
in place.
4. Disconnect gas line and pilot tube on the inlet
side of safety valve.
5. Disconnect pilot tube and gas line on the outlet
side of the safety valve.
6. Disconnect the thermocouple from the safety
valve.
CAUTION: The thermocouple line is fragile.
Do not kink it.
7. Remove the safety valve from the unit.
8. Install the new safety valve, mounting screws
(if used) and thermocouple.
Note: Do not kink the thermocouple.
9. Apply gas approved thread sealer to all gas
and pilot tube ttings.
10. Check for leaks.
11. Install the bottom cover.
12. Connect the unit to its gas supply
13. Light the pilot light.
14. Replace the galvanized burner liner.
15. Verify that the burner lights properly.
Thermocouple Replacement
Figure 6.
Thermocouple
General
The thermocouple is connected to the safety
valve at one end. The probe end is near the pilot
burner.
1. Shut off the gas supply.
2. Remove the galvanized burner liner from the
pan.
3. Remove the screws the hold the bottom cover
in place.
4. Unscrew the thermocouple from the safety
valve.
5. Remove the probe end from the burner
area.
6. Replace the thermocouple.
CAUTION: The thermocouple line is fragile.
Do not kink it.
7. Perform leak test at safety valve tting.
8. Install the bottom cover.
9. Turn on the gas supply.

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Gas Operated Foodwarmers
10. Light the pilot.
11. Replace the galvanized burner liner.
12. Verify the burner lights properly.
Pilot Replacement
Direct Burn Pilot
Figure 7.
Direct Burn Pilot
The pilot, Figure 7, for a direct burn unit is
connected directly to the gas supply manifold.
1. Shut off the gas supply.
2. Remove the galvanized burner liner from the
pan.
3. Remove the screws the hold the bottom cover
in place.
4. Remove the pilot tube from the manifold.
5. Slide the pilot tube away from the burner and
out of the unit.
6. Place gas approved thread sealer on the new
pilot tube tting.
7. Replace the pilot tube.
8. Perform leak test.
9. Install the bottom cover.
10. Turn the gas supply on.
11. Replace the galvanized burner liner.
12. Light the pilot.
13. Verify that the burner will light correctly.
Safety Valve Pilot
Figure 8.
Safety Valve Pilot
On units with a safety valve the pilot, Figure 8, is
connected to the safety valve.
1. Shut off the gas supply.
2. Remove the galvanized burner liner from the
pan.
3. Disconnect the pilot tube from the safety
valve.
4. Remove the pilot assembly from the unit.
5. Place gas approved thread sealer on new pilot
tube tting.
6. Replace pilot assembly.
7. Perform leak test.
8. Install the bottom cover.
9. Turn gas supply on.
10. Light pilot.
11. Replace the galvanized burner liner.
12. Verify that the burner lights properly.

Gas Operated Foodwarmers
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Burner Replacement
Tube Burner
Figure 10.
Tube Burner
1. Turn off the gas supply.
2. Remove the galvanized burner liner, Figure
10.
3. Remove the burner from the gas supply
tube.
4. Replace the burner.
5. Turn on the gas supply.
6. Light the pilot.
7. Verify that the burner lights properly.
8. Replace the galvanized burner liner.

11
Gas Operated Foodwarmers

Gas Operated Foodwarmers
12
Duke Manufacturing Company
2305 N. Broadway
St. Louis, MO 63102
Phone: [phone]
Toll Free: 1-800-735-3853
Fax: [phone]
www.dukemfg.com
P/N 219218