SERVICE MANUAL
GHF SERIES HEAVY DUTY
RANGE MATCHING GAS
FRYERS & FRYMATES
MODELS
GHF91G ML-135503
GHF90G ML-135504
- NOTICE -
This manual is prepared for the use of trained Vulcan Service
Technicians and should not be used by those not properly
qualified. If you have attended a Vulcan Service School for this
product, you may be qualified to perform all the procedures
described in this manual.
This manual is not intended to be all encompassing. If you have
not attended a Vulcan Service School for this product, you
should read, in it's 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.
Reproduction or other use of this Manual, without the express
written consent of Vulcan, is prohibited.
For additional information on Vulcan-Hart or to locate an authorized parts
and service provider in your area, visit our website at www.vulcanhart.com
VULCAN-HART
DIVISION OF ITW FOOD EQUIPMENT GROUP, LLC
WWW.VULCANHART.COM
– 1 –
P.O. BOX 696, LOUISVILLE, KY 40201-0696
TEL. (502) 778-2791
FORM 35618 (11-04)
TABLE OF CONTENTS
GENERAL .............................................................................................................................................................. 3
Introduction ............................................................................................................................................... 3
Installation ................................................................................................................................................ 3
Oil Filtering ................................................................................................................................................ 3
Operation ................................................................................................................................................... 3
Cleaning .................................................................................................................................................... 3
Lighting Pilot ............................................................................................................................................. 3
Specifications ........................................................................................................................................... 3
Gas Data............................................................................................................................................. 3
Tools ......................................................................................................................................................... 3
Standard ............................................................................................................................................. 3
REMOVAL AND REPLACEMENT OF PARTS ..................................................................................................... 4
Covers and Panels ................................................................................................................................... 4
Door .................................................................................................................................................... 4
Front Panel ......................................................................................................................................... 4
Burners ...................................................................................................................................................... 4
Thermostat ................................................................................................................................................ 5
High Limit .................................................................................................................................................. 6
Thermopile ................................................................................................................................................ 6
Pilot Orifice ............................................................................................................................................... 7
Combination Valve ................................................................................................................................... 7
Fry Tank .................................................................................................................................................... 8
SERVICE PROCEDURES AND ADJUSTMENTS ............................................................................................. 9
Millivolt Controls Test .............................................................................................................................. 9
Thermostat Calibration ............................................................................................................................. 9
Calibration Steps ................................................................................................................................9
Pilot Adjustment ...................................................................................................................................... 10
Burners, Nozzles and Orifices ................................................................................................................10
Burners .............................................................................................................................................. 10
Nozzles and Orifices.........................................................................................................................10
Combination Valve Regulator Adjustment ..............................................................................................11
ELECTRICAL OPERATION ................................................................................................................................12
Control System Description ....................................................................................................................12
System Condition Quick Check Procedures ..........................................................................................12
Schematic ................................................................................................................................................13
Component Function ...............................................................................................................................13
TROUBLESHOOTING .........................................................................................................................................14
© VULCAN-HART, 2004
– 2 –
GENERAL
INTRODUCTION
Models
This service manual was written for:
GHF91G Gas Fryers and GHF90G Gas Frymates.
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, which is sent with each fryer.
OIL FILTERING
Filtering instructions are included in the Installation
and Operation Manual.
NOTE: If pilot does not remain lit, repeat steps 2
through 5, but allow a longer period of time before
releasing the combination valve knob. Adjust pilot
flame, if necessary, as outlined under Pilot Adjustment
in Service Procedures and Adjustments.
6. Turn combination valve knob to ON.
SPECIFICATIONS
Gas Data
MODEL No. Tubes BTU/HR
GHF91G 4 120,000
GHF90G 00
TOOLS
OPERATION
Detailed operation instructions are included with each
fryer in the Installation and Operation Manual.
CLEANING
Detailed cleaning procedures are included in the
Installation and Operation Manual.
LIGHTING PILOT
1. Turn thermostat OFF.
2. Push combination valve knob in and turn to
OFF.
3. Wait 5 minutes for unburned gas to vent.
4. Push combination valve knob in and turn to
PILOT.
5. While holding the combination valve knob in,
light the pilot with a lit taper. Hold the
combination valve knob in for approximately
30 seconds before releasing.
Standard
• Hand tools (standard set)
• VOM with AC current tester (any quality VOM
with a sensitivity of at least 20,000 ohms per
volt can be used)
• Gas test kit
• Temperature tester (thermocouple type)
• Manometer
– 3 –
REMOVAL AND REPLACEMENT OF PARTS
COVERS AND PANELS
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
Door
1. Open door and using a 5/16" wrench or ratchet,
remove (2) screws securing the top door
mounting bracket to the left body side channel.
BURNERS
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
1. Open door panel.
2. Loosen (Do not remove) the two mounting
bolts at the top of each burner.
2. Hold door in one hand and lift the door panel
assembly off of the bottom hinge.
3. Reverse this procedure to reinstall the door
panel.
Front Panel
1. Using a flat head screwdriver, remove (2)
screws holding the front panel in place.
2. Remove the panel from the unit.
3. Push burner up while pulling the bottom of the
burner forward to clear the burner nozzle.
4. Reverse the procedure to install.
3. Remove heat shield.
– 4 –
THERMOSTAT
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
1. Drain shortening from fry tank.
2. Remove left burner as outlined under Burners.
3. Remove thermostat knob by pulling knob off
thermostat shaft.
4. Remove thermostat mounting screws and
remove thermostat from mounting bracket.
6. Loosen the packing nut and holding nut.
7. Remove the thermostat bulb from the clamp.
5. Remove wire leads from the rear of the
thermostat, noting all connections for
reassembly.
8. Pull the thermostat bulb through the underside
of the fry tank and remove the thermostat
assembly.
9. Reverse the procedure to install. When
installing the new thermostat assembly, do
not kink the thermostat capillary. Wrap threads
of packing nut with Teflon tape to prevent
leakage.
– 5 –
HIGH LIMIT
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
1. Drain shortening from fry tank.
2. Remove wire leads from high limit, noting all
connections for reassembly.
7. Pull the high limit bulb through the underside
of the fry tank and remove the high limit
assembly.
8. Reverse the procedure to install. When
installing the new high limit assembly, do not
kink the high limit capillary. Wrap threads of
packing nut with Teflon tape to prevent
leakage.
THERMOPILE
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
3. Remove high limit from mounting bracket.
4. Remove left burner as outlined under Burners.
5. Loosen the packing nut and the holding nut.
6. Remove the high limit bulb from the clamp.
WARNING: ALL GAS JOINTS DISTURBED DURING
SERVICING MUST BE CHECKED FOR LEAKS.
CHECK WITH SOAP AND WATER SOLUTION
(BUBBLES). DO NOT USE AN OPEN FLAME.
1. Disconnect thermopile lead wires as outlined
under High Limit.
2. Remove (1) 10-24 screw and pull the pilot
assembly away from the tank body.
3. Remove (2) side screws to detach the pilot
from the holding bracket.
– 6 –
4. Remove pilot tubing from pilot.
5. Remove screws holding pilot bracket.
6. Remove thermopile from pilot bracket.
7. Reverse procedure to install.
PILOT ORIFICE
2. Remove the right hand burners as outlined
under Burners (optional).
3. Disconnect lead wires from combination valve
and mark for reconnecting.
4. Disconnect pilot tubing from combination
valve.
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
WARNING: ALL GAS JOINTS DISTURBED DURING
SERVICING MUST BE CHECKED FOR LEAKS.
CHECK WITH SOAP AND WATER SOLUTION
(BUBBLES). DO NOT USE AN OPEN FLAME.
1. Remove pilot assembly from fryer as outlined
under thermopile.
2. Remove hex nut on the bottom of the pilot to
expose the orifice.
3. Replace orifice and reverse procedure to
assemble.
COMBINATION VALVE
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
WARNING: ALL GAS JOINTS DISTURBED
DURING SERVICING MUST BE CHECKED FOR
LEAKS. CHECK WITH SOAP AND WATER
SOLUTION (BUBBLES). DO NOT USE AN OPEN
FLAME.
5. Disconnect combination valve union (Fig.1)
and pressure fitting (Fig. 2).
6. Remove the combination valve from the fryer.
7. Reverse procedure to install.
Fig.1 Fig. 2
1. Disconnect fryer from main gas supply.
– 7 –
FRY TANK
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
WARNING: ALL GAS JOINTS DISTURBED DURING
SERVICING MUST BE CHECKED FOR LEAKS.
CHECK WITH SOAP AND WATER SOLUTION
(BUBBLES). DO NOT USE AN OPEN FLAME.
1. Disconnect fryer from main gas supply.
2. Drain oil from tank.
3. Remove baskets, fryer basket hanger and
crumb screen.
8. Remove screws holding pilot assembly to
bracket and remove pilot assembly.
9. Lift the fry tank up and out of cabinet. Carefully
place the tank assembly on the floor (this
procedure requires two people).
10. Remove the tank ball drain valve.
4. Remove screws holding fry tank.
5. Remove burners as outlined under Burners.
6. Remove the manifold bracket from the tank
assembly.
7. Remove thermostat and high limit as outlined
under Thermostat and High Limit.
11. Reverse the procedure to install new tank.
– 8 –
SERVICE PROCEDURES AND ADJUSTMENTS
MILLIVOLT CONTROLS TEST
1. Verify proper gas (natural or propane) is
present.
2. Check for correct wiring and secure
connections.
3. Verify the pilot flame is adjusted properly as
outlined in Pilot Adjustment.
4. If the pilot is not lit, light pilot as outlined
under Lighting Pilot. Allow the pilot to burn for
3 to 4 minutes to stabilize.
A. If the pilot remains lit, proceed to step 6.
B. If the pilot will not remain lit, proceed to
step 5.
5. Connect DC voltmeter to terminals TH TP
and TP of combination valve. Relight the
pilot, hold the combination valve knob in and
allow the pilot to burn for 3 to 4 minutes to
stabilize.
A. If the voltage measures 450 millivolts or
greater and the pilot will not stay lit,
replace the combination valve.
B. If the voltage is less than 450 millivolts,
measure the voltage at terminals NO and
C of high limit.
1) If the voltage is 500 millivolts or
more, replace the high limit.
7. Turn combination valve to ON. Turn
thermostat to a setting higher than the
shortening temperature.
A. If the voltage measures 150 millivolts or
more but the burners do not ignite, replace
the combination valve.
B. If the voltage is less than 150 millivolts,
measure the voltage between terminals
NO of the high limit and TP of the
combination valve.
1) If the voltage is 200 millivolts or
greater, replace the thermostat.
2) If the voltage is less than 200
millivolts, replace the combination
valve.
THERMOSTAT CALIBRATION
1. Place temperature tester in the fry tank near
the thermostat bulb.
2. Set the thermostat to 300°F and allow the
temperature to stabilize.
3. Check the temperature tester reading against
the thermostat dial reading. If there is
a variance of more than ±20°F (280°F to
320°F), calibration is required.
Calibration Steps
2) If the voltage is less than
500 millivolts, disconnect the lead
wire from terminal TH TP of the
combination valve and remeasure
voltage at the high limit.
a. If the voltage is less than
500 millivolts, replace the
thermopile.
b. If the voltage is 500 millivolts or
more, replace the combination
valve.
6. Connect DC voltmeter to terminals TP and
TH of combination valve.
1. Remove thermostat knob from shaft.
2. Using a small screwdriver, rotate the setscrew
inside the hollow shaft counterclockwise to
increase the temperature or clockwise to
decrease the temperature (1/4 turn equals
approximately 18°F).
3. Allow temperature to stabilize and recheck
temperature. Repeat until the temperature
falls within the limits as stated in step 3 under
Thermostat Calibration.
4. Install thermostat knob and set dial to 350°F.
– 9 –
5. Allow temperature to stabilize at new setting
and compare temperature tester to dial setting.
Recalibrate if the temperature does not fall
within the range of 330°F to 370°F.
6. If the temperature does not fall within the
limits at both settings, replace the thermostat.
BURNERS, NOZZLES AND ORIFICES
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
Burners
PILOT ADJUSTMENT
1. Light pilot as outlined under Lighting Pilot on
page 3.
2. If the flame does not extend beyond the outer
edges of the pilot shield 1/2", or extends more
than 1/2", an adjustment is necessary.
3. Remove the cap covering pilot adjustment
screw. Turn the recessed pilot adjustment
screw counterclockwise to increase the size
of the flame or clockwise to decrease the
size of the flame.
If the burner ports become clogged, the fryer will not
operate properly. If the burner is cracked, it must be
replaced.
1. Remove burner(s) as outlined under Burners.
2. Check burner(s) for cracks and clogged ports.
3. If the ports are clogged, wash burner(s) in
warm, soapy water. If this does not remove
obstructions, a #37 drill bit can be used (do
not use in an electric drill; hand-turn only).
Nozzles and Orifices
1. Remove the burners as outlined under
Burners.
2. Hold the burner nozzle with channel locks
and remove the orifice. Check the orifice for
obstructions or damage.
3. If the orifice is clogged, wash the orifice in
warm, soapy water. If this does not remove
obstructions, a #37 drill bit can be used (do
not use in an electric drill; hand-turn only).
– 10 –
4. With channel locks, remove the burner nozzle.
5. Reverse procedure to install new burner
nozzle and orifice.
COMBINATION VALVE REGULATOR
ADJUSTMENT
3. Turn on the gas and light the pilot as outlined
under Lighting Pilot in General.
4. Turn the combination valve to ON.
WARNING: SHUT OFF THE GAS BEFORE
SERVICING.
Accurate gas pressure adjustments can only be
made with the gas on and the burner lit. If the
incoming line pressure to the valve is less than the
minimum stated, then the pressure cannot be set
correctly.
The combination valve is preadjusted for natural or
propane gas as specified on the rating plate. The
natural gas rating is 4" W.C., and the propane rating
is 10" W.C.
1. Turn the combination valve knob to OFF.
5. Set the thermostat so the burners will come
on.
6. Read the pressure gauge. The manifold
pressure reading should match the pressure
rating on the data plate.
A. To adjust, remove the cap covering the
manifold pressure adjustment screw. Turn
the recessed manifold pressure
adjustment screw counterclockwise to
decrease pressure or clockwise to
increase pressure.
2. Remove the plug from the submanifold and
install pressure gauge at this point.
7. Install the cap and check for proper operation.
– 11 –
ELECTRICAL OPERATION
CONTROL SYSTEM DESCRIPTION
1. The thermopile (TP) provides the total control
voltage for this system.
A. One side of the thermopile is connected
to the common (C) of the high limit (HL).
B. The other side of the thermopile is
connected to the normally open (NO)
contacts of the high limit.
C. The common of the high limit (below the
high limit trip temp.) is connected through
the normally closed (NC) contacts of the
high limit, through wire 3 to the
combination valve pilot connection
common.
D. The other side of the pilot valve is
connected through wire 4 to wire 1 to the
high limit normally open contacts which
hold the pilot valve open.
1) If the high limit trips, connection is
made from the common to the
normally open contacts, turning off
pilot valve voltage. The gas valve
closes.
3. Total Shutdown.
A. When the high limit trips, 0.0 millivolts
will read across both coils of the
combination valve, causing both valves
to close.
B. Pilot relight cannot be accomplished until
oil cools sufficiently to allow high limit to
close.
C. If any wire in the system is cut or broken,
the system will shut down.
SYSTEM CONDITION QUICK CHECK
PROCEDURES
1. Use the Pilot Lighting procedure and check
millivolts (mV) at wires 3 and 4.
A. If the pilot lights, then pilot combination
and high limit are good.
B. If the pilot will not stay lit, check high
limit and open the thermopile circuit. It
should read 300 mV; if there are Ø volts,
check high limit. If the high limit is good,
replace combination valve.
2. Thermostat Control.
A. One side of the millivolt supply is
connected through the high limit system,
as described above, to the thermostat
common (wire 3) of the combination valve.
B. The other side of the thermopile is
connected from the normally open
contacts of the high limit to the thermostat
through wire 1.
C. When the thermostat calls for heat (closed
circuit) power from the thermopile is then
connected to the other combination valve
thermostat connection through wire 2.
D. If the high limit trips, the thermopile is
connected across zero ohms, the output
voltage of the thermopile drops to 0.0
millivolts, and the thermostat coil of the
combination valve drops out, shutting
the thermostat valve.
C. Check for voltage at disconnected
thermopile. It should read 300 mV; if
there are Ø volts, replace thermopile.
Check high limit. If the high limit is good,
replace combination valve.
2. Turn on thermostat; burners should light.
A. If the burner does not light, check the
following:
1) Voltage at combination valve at
wires 2 and 4.
2) If correct voltage is present, then
check combination valve.
3) If there are Ø volts, check voltage
between wire 3 of combination
valve and wire 1 of thermostat. If
correct voltage is present, then
check resistance of thermostat
and wire 32. If there is no voltage,
check resistance of wire 1 to
normally open contacts of high
limit.
– 12 –
SCHEMATIC
COMPONENT FUNCTION
Thermostat - Millivolt type with capillary bulb, single-throw break on temperature rise. Temperature range of 200°F
to 400°F.
Thermopile - Millivolt control with 24" capillary. Rated to generate 500 millivolts.
Combination Valve - Regulates gas flow to burner and pilot. Provides pilot safety.
Hi-Limit - Prevents overheating of fryer in the event of thermostat failure. Opens at 450°F and automatically resets
at 415°F.
– 13 –
TROUBLESHOOTING
SYMPTOM
1. The temperature of the shortening drops,
or excessive recovery time is required.
2. Pilot won't stay lit. Fryer shut off.
3. Rapid shortening breakdown, crumbs and
specks in frying compound.
POSSIBLE CAUSE
A. Insufficient gas supply to unit.
B. Ventilating system pulling heat out of
heat exchanger and flue box.
C. Overloading fryer capacity.
A. Malfunctioning thermopile or loose/dirty
connection in thermopile.
B. Malfunctioning shutoff valve.
C. Pilot burner orifice and air openings need
cleaning.
A. Excessive temperature settings (over
375°F).
B. Shortening not being filtered regularly.
C. Incorrect preparation of breaded food.
• Do not use salt.
• Allow breading time to adhere to
food.
• Do not allow loose flour to fall into
shortening from hands.
D. Do not add strainings or drippings from
meat fats to shortening.
E. Use correct shortening and follow
temperature recommendations.
F. Take out 10% to 15% of the shortening.
G. Check thermostat settings with
thermometer periodically.
– 14 –
TROUBLESHOOTING
SYMPTOM
4. Leaking tank.
5. Pilot burner flames adjusted properly, but
fluctuate to very low and blow out easily.
POSSIBLE CAUSE
A. Foam-over by depleted shortening permits
oil to drip from the tank surface, giving the
appearance of leaking.
B. Careless draining procedures. Gas valve
should be in the PILOT or OFF position
before draining oil. Burners heating an empty
tank will damage tank joints.
C. Carbon buildup causes rapid attack on tank
by promoting acid formulation.
A. Check gas pressure at submanifold fitting on
fryer when fryer is in operation. Check all
other equipment on the same gas line in
operation.
B. Pressure at submanifold (pipe on which
burners are mounted) should not be less than
4.0" W.C. (natural and mixed gas) or 10"
W.C. for propane gas.
– 15 –
NOTES
FORM 35618 (11-04) PRINTED IN U.S.A.
– 16 –
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