Vulcan-Hart ET8 Guide

VULDHI
SERVICE & PARTS MANUAL FOR
ELECTRIC CONVECTION OVENS
MODELS;
ET8, ET8R, ETH8, ETH8R,
ET88, ET88R, ETH88, ETH88R,
ET10, ET10R, ETH10, ETH10R,
ET1010, ET101R, ETH101, ETH11R
(208/240, 480,440, 220/380 VOLTS - ALL PHASES)
VULCAN-HART COMPANY, P.O. BOX 696 LOUISVILLE, KY 40201-0696, TEL [phone]
FORM F-30519 Rev. B (10-91) (Fwmerly 115725)

SERVICE AND PARTS MANUAL
ET8. ET10 SERIES ELECTRIC CONVECTION OVENS INDEX
PLEASE KEEP THIS MANUAL FOR FUTURE REFERENCE
Your Vulcan oven is produced with quality workmanship performance .The manufacturer suggests that you
andmaterisJ. Pr<^erinstallation,usageandmaintenance thoroughly read this entire manual and carefully follow
of your oven will result in many years of satisfactory alt of the instructions provided.
DESCRIPTION PAGE
INDEX
3
TROUBLESHOOTING GUIDE
4.5
GENERAL SERVICE INFORMATION
6
PARTS DESCRIPTION AND REPLACEMENT
7-10
SWITCH PANEL
7,8
MASTER SWITCH
7
OVEN INDICATOR LIGHT
7
THERMOSTAT
7
LOAD CONTROL INDICATOR LIGHT
8
LOAD CONTROL
8
TIMER (ONE- OR FIVE-HOUR MODELS)
8
AUXILIARY FAN SWITCH
8
OVEN LAMP SWITCH
8
BLOWER MOTOR
9
OVEN LIGHTS
9
OVEN HEATING ELEMENTS
9
DOOR SWITCH
9
POWER PANEL ASSEMBLY
10
CONTACTOR
10
RELAY
10
BUZZER 10
CIRCUIT BREAKER
10
TRANSFORMER
10
REPUCEMENT PARTS LIST 11-30
3

TROUBLESHOOTING GUIDE
WARNING: CERTAIN PROCEDURES IN THIS
SECTION REQUIRE ELECTRICAL TESTS OR
MEASUREMENTS WHILE POWER IS APPLIED TO
THE MACHINE. EXERCISE EXTREME CAUTION AT
ALL TIMES. IF TEST POINTS ARE NOT EASILY
ACCESSIBLE, DISCCWNECT POWER, ATTACHTEST
EQUIPMENT. AND REAPPLY POWER TO TEST.
This section provides a guide for troubleshooting and
covets some of the more common problems with the
equipment. Servicing personnel need to become familiar
with the draiit aid the components in order to be able to
also follow a logics^ sequence of troubleshooting and
repair malfunctions not mentioned in the following
paragraphs.
The instruments necessary for troubleshooting are:
A. A .C. Voltmeter to measure line voltages up to 480
volts.
B. A.C. Ammeter to mes^ure line currents up to 160
amps for 208 volt, 1-phase model.
C. Accurate thermometerto measure oven temperature
up to 500®F.
In the following paragraphs, the voltmeter is used to
measure the voltage between 2 phases on 240,
440, 480 volt and between 1-phase and nmibal on
220/380 and 240/415 volt supplies. Do not measure the
voltage to the chassis ground. For the sake of
simplicity, when the measured voltage is referred to as
208 volt, it is assumed that the supply Is 208 volt. When
supply is 240 or 220, the measured voltage should also
be 240 or 220- It is also assumed that flie voltage rating
of the oven matches exactly (within the allowable
supply tolerance) that of the field supply. Refer to the
appropriate wiring diagram.
With the main power and oven circuit breakers ON, the
master switch turned to ttie ON position, and the oven
door closed, tiie following conditions may occun
PROBLEM
CORRECTION PROCEDURE
No blower. No heat.
Depress oven light swteh or turn timer knob tij “0" position. If light comes
on and buzzer sounds, follow Step B; if not, follow Step A.
A. Measure voltage between leads 42 and 48 of master switch. If 208
volts, measure voltage across 21 and 22. If 208 volts, chedc for bad
connection to switch terminal. If no voltage, check for tripped 15-amp
breaker or bad connection to the breaker.
B. Turn load control to HI. If load control indicator light is Rt, chedi Mower
or motor relay. If indicator light is not iit, depress auxOtary fan switch. If
blower comes on, door switch needs to be adjusted (see PARTS
DESCRIPTION AND REPLACEMENT in this manual). If not. check for
proper connections to door switch on leads 12,13,14.
Btower is (with auxiliary
fan switch de-energized), but
no heat.
Turn thermostat knob to about SSO^F. If oven indicator Mght is lit, foltow
Step B; If not, follow Step A.
A. Measure voltage between the phases on load side of contactor. If 208
volts exist, check heating elements or connecting leads. If no voltage,
check voltage on supply side of contactor. If 208 volts, contactor is bad.
if no voltage. ched< main circuit breakers and supply voltage.
B. Check voltage on contactor coil teiminals. If 208 vMts eost, Mjt
contactor does not pull in, contactor is bad. If no voltage, check voltage
across terminals HI and H2 of toad control switdi. If 208 volts, look for
bad connection on leads 60 and 61. If no voltage, check load control
switch.
4

PROBLEM
CORRECTION PROCEDURE
Only one side of oven heats Check oven circuit breaker and contactor leads going to the cool side,
up. Check heating elements.
Oven heats up very slowly Check for tripped breakers, supply voltage, contactor or heating elements,
with no food in it. Compare amp reading on each phase lead with the expected nominal.
They should match closely.
Oven heats up properly Meals containing excessive moisture can cause temperature drop. Also,
when empty, but as soon as excess load can cause temperature drop. The K.W. rating of the oven may
food is put in it, temperature not be adequate to properly handle type or quantity of food in the oven,
drops and oven never Remember that the larger the quantity of food, the higher the setting should
recovers. be on the load control switch.
Oven temperature does not Place a temperature measuring device on center rack. Allow thermostat to
correspond with thermostat cycle at least 3 times. If thermostat setting and thermometer reading do not
setting. correspond within ± 20®F, recalibrate thermostat as described in PARTS
DESCRIPTION AND REPLACEMENT section in this manual.
Oven temperature keeps If thermostat Indicator light cycles on and off, check contactor (contacts
increasing beyond setting of welding). If thermostat light remains ON, check thermostat (contacts
tiiermostat. welding).
With master sv/ftch OFF, Check contactor (contacts welded shut) or for shorted heating element to
oven heats up. ground (the short could either be internally within ttie element or externally
through the connecting leads of the elements).
Motor turns off and The internal thermal protector of the motor is sensing a too high
automatically comes back on temperature which is caused by:
after a few minutes.
A. High current — check for clockwise rotation of shaft, for any binding on
shaft of blower wheel (wheel should be rotated freely by a hand touch).
If none of the above, check for problem vwth motor.
B. High ambient—check for hot air leakage from inside oven to back
through light or motor housings. Check to see if hot air is blowing on
motor from adjacent equipment. Check for proper ventilation in the
area.
NOTE; Occasionally the overcurrent affects the circuit breaker (15 amp
breaker) before it does the thermal protector, and the circuit breaker will
keep tripping to the OFF position.

GENERAL SERVICE INFORMATION
WARNING: THE OVEN AND ITS PARTS ARE HOT;
USE CARE WHEN OPERATING, CLEANING AND
SERVICING THE OVEN.
Vulcan electnc ovens are manufaclured for use with
the voltage specified by the rating plate which is
mounted above the switch panel. All double stack oven
rating plat^ list total K.W. rating for both ovens on each
rating plate.
For installation procedires in tfie United States of ^erica,
refer to the National Electrical Code, ^Si/NFPA No. 70
(latest edition).
LOADING
Before loading, set the load control dial to flie proper
setting for product being cooked.
OPENING OVEN DOORS
WARNING: DO NOT STAND DIRECTLY IN FRONT
OF THE OVEN WHILE OPENING THE OVEN DOOR.
ALTHOUGH OPENING THE OVEN DOOR WILL
AUTOMATICALLY SHUT THE FAN OFF. SOME HEAT
ESCAPES. STEP AWAY TO AVOID HOT AIR.
Before opening oven doors, fMJsh auxiliary fan switch to
OFF position.
BACK-UP THERMOSTAT
All ET10, ET1 OR, ET1010 aid ET101R ovens employ a
bad<-up thermostat. Should the primary thermostat fall,
the badc-up thermostat is set to open at 550®F aid
reclose when the oven temperature cools to 400'‘F.
CONVERTING ET8 OR ET8R OVENS TO ET88 OR
ET88R
WARNING: DISCONNECT ELECTRICAL POWER
SUPPLY AND PLACE A TAG AT THE DISCONNECT
SWITCH TO INDICATE YOU ARE WORKING ON THE
CIRCUIT.
ET8 and ET8R ovens (single section oven) are
constructed similarly to tee top section of ET88 and
ET88R ovens. In order to ainvert an ET8 or ET8R to an
ET88 or ET88R (double section) in the fi^, disconnect
the electrical supply leads from the old oven and move
the oven away. Locate the new oven (ET8 or ET8R.
bottom section) in the desired location and mount the
old ET8 or ET8R on top of the new oven, foltawing
installation instructions in the Installation and Operation
Maiual.
In 220^80 or 240/415 volt models, the oven r^iaates on
either 220 or 240 volts between the neutral and tee
phase leads: therefore, it is essential that the neutral
wire, independent from grounding wire which is used to
ground the oven frame, be included in the main supply
leads.
6

PARTS DESCRIPTION AND REPLACEMENT
WARNING; DISCONNECT THE ELECTRICAL
POWER SUPPLY AND PUCE A TAG AT THE
DISCONNECT SWITCH TO INDICATE YOU ARE
WORKING ON THE CIRCUIT.
SWITCH PANEL
In order to replace the components on the switch panel,
first taJte off the protective bade cover by removing the
four screws on both sides that mount the cover to the
switch panel. Reinstall the back cover after repair work
is completed.
Master Switch
The master switch Is the main ON-OFF D.P.S.T.
(double-pole, single-throw) switdi providing the supply
voltage to the controls.
To replace, remove back cover from switch panel.
Locate toggle switch from back of control panel. Note
switch wire connections. Remove wire connections.
Remove toggle switch holding nut from front of control
panel. Pull switch tiirough back of control panel. Install
new switch ^d reassemble control panel.
Oven Indicator Light
Light ON indicates that the oven has not reached the
thermostat diai setting and Is calling for heat Light
OFF indicates that the set temperature has been
reached and that the heating elements are de¬
energized.
To replace, follow procedure described in MASTER
SWITCH section above.
Thermostat
A S.P.S.T. {single-pole, single-throw) sn^ action
switch controls the temperature of the oven from 200‘’F
to SOO^F. The normally closed contacts of the thermostat
provide power to the coil of the heating element
contactor as long as the heat is needed. Once the set
temperature is reached, the contacts open, de¬
energizing the contactor coil.
To replace the thermostat remove the thermostat bulb
from its two retaining clips located in the right rear of
the oven cavity, push the bulb and the capillary tube
through the grommet in the cavity w^l, remove the
knob and the two mounting screws and pull the
thermostat off the back of the panel.
For a calibration check, use a calibrated potentiometer
with the thermocouple located in the center of the
center rack. Set the dial to a mid-range temperature
and allow the oven to cycle at least three times.
if measured temperature is outside of 20'*F of the dial
setting, remove the thermostat Imob and recalibrate by
turning screw "A” clodwise to decrease temperature
or counterclockwise to increase temperature. A % turn
of screw “A” causes a temperature shift of 35®F (Fig, 1).
I PL-501191
7

Load Control Indicator Light
Similar to the Oven Indicator Light in construction, the
light ON indicates that the load control switch is
operating between the LO and HI positions. Unlike ttie
Oven Indicator Light, this light remains ON even when
the set terr^rature is reached.
Load Control
A D.P.S.T. cycling switch which varies, according to Its
setting, the percent on-time of the output as shown
below:
DIAL SETTING PERCENT ON-TIME
HI
Hl-
MED+
MED
MED-
LO+
LO
OFF
100%
83%
72%
60%
48%
37%
27%
0%
The load control, as shown schematically (Fig. 2), is
connected in series with the thermostat, thus providing
a variable rate of temperature rise to reach the
thermostat setting, as well as maintaining the final set
temperature. Therefore, with load control set at LO, it
will t^e much longer to readi a desired temperature
than with a setting of HI. The cooking chart in the
Installation and Operation Manual shows the necessary
dial setting for different food products.
LQJtCt
{ fOJOttm tamiiam vt\
«OUE3I09 j
To replace, remove the knob and the locknut. To
reinstall, make sure the dimples on the face of the
switch fall in the slot of the switch panel In order to
prevent it from rotating.
Timer (One- or Five-Hour Models)
The normdiy open and common contacts of the electric
timer are connected together, en^tzing the timer
motor when the knob is set to the desired pcsriWon.
Once the timer completes its set interval (returns to ttie
zero mark), the common terminal disconnects from the
timer motor (shuts the motor off) and connects with the
buzzer. The buzzer will continue to sound until the
knob is manually turned to flie HOLD position where
all contacts are opened (timer motor and buzzer turned
off). (Fig. 3)
To replace, remove the knob and the locknut Reinstall
same as the Load Control.
Auxiliary Fan Switch
A D.P.S.T, switdi whkrfi, when depressed, energizes
a relay which overrides the door interlock, allowing the
blower to operate with the oven door opened.
To replace the switch, compress the spring dips on the
top and bottom of the switch while forcing It out the
front of the switch panel.
Oven Lamp Switch
Similar in construction to the Auxiliary Fan Switch. The
switch turns on the two interior lights. To replace,
follow the same procedure as for ttie Auxiliary Fan
Switch.
8
Schematic Load Control Connection
Fig. 2
Rear View Schematic Compon^t
Fig. 3

BLOWER MOTOR
The blower motor has internal thermal protection, and its
sealed bearings do not require any lubrication. The
rrK)unting of the blower assembly allows servicing from
inside the oven as follows:
1. Remove fan cover.
2. Loosen set screw on the airotor with an Allen
wrendi.
3. Pull airotor forward off the motor shaft with a wheel
puller.
4. Remove the four nuts holding the motor mounting
plate.
5. Pull ttie motor assembly forward and reset it on
cavity bottom.
6. Remove the junction box cover and the supply
leads.
7. Reset the motor on its back. Remove the four flat
head screws, lockwashers, nuts and spacers used
to fasten the motor mounting plate to the motor.
The motor is suitable for connection of two different
voltage supplies. Check the connection instruction
inside the motor junction box cover to assure proper
connection for the available voltage supply.
The direction of rotation is clockwise as viewed from in
front of the oven. The 1 -phase motois are internally
designed for clockwise rotation. On 3-phase motors,
interchange any two supply leads to convert
counterdockwlse to clockwise rotation.
8. Remove the two screws holding the side liner. Pull
the liner backward and out
9. Remove the element clamp covers holding the
element to the oven side.
10. Remove the three screws holding the element
bracket to the top.
11. Remove the element and the wires down from the
top of the oven.
12. Remove the connecting supply lead.
OVEN LIGHTS
The two 50 watt. 120 volt bulbs £U'e connected in series
in these electric ovens.
To replace lamps, remove the four mounting bolts
holding the lamp window assembly from the rear of the
unit. Both the lamp, as well as the socket can now be
serviced. Make sure the replacement lamp is of high
temperature type and is not larger than 50 watts.
OVEN HEATING ELEMENTS
The three heating elements mounted on each side of the
oven behind the perforated side liner can be sen/iced
from inside the oven as follows:
1. Remove the two screws holding the liner. Pull tfie
liner backward and out.
2. Remove the element damp covers holding element
to the oven side.
3. Remove the three screws holding the element
bracket to the top.
4. Remove the element and the wres down from the
top of the oven.
DOOR SWITCH
With the oven door dosed, the normally open contact
of the door switch is dosed providing power to the
element and motor controls. When the door opens, tiie
normally open contact is de-energized, and the element
contactor and the blower are turned off.
To adjust or replace the door switch, remove the two
mounting screws on the underside of the top finishing
piece. Depress the door catches up inside the top
channel and pull the top finishing piece off.
The door switch is controlled by a cam-type device
mounted to the top of the right hinge pin. The cam
must actuate the door switch when the door is
approximately 3" away from being dosed.
To replace the door switch, remove the mounting
screws on the door switch support bracket and remove
the switch from the bracket.
g

POWER PANEL ASSEMBLY
Contactor
The 4-pole (208,240 volt models) and 3-pole (220/380,
240/415 & 480 volt models) contactors, when energized
by the thermostat and load control, provide power to
the heating eiemente.
To reji^ace, remove the two mounting screws and
disconnect the leads.
Relay
The S.P.D.T. relay provides power to the blower motor
(on units equipped with the auxiliary fan switch) in order
to override the door interlock.
To replace, compress the ^ing clips on ttie top and
bottom of the switch while forcing it out the front of the
smtdi panel.
Buzzer
Signalled by the timer, the buzzer sounds when the
preset time is completed.
To replace, cut both wires approximately 3" from the
buzzer ^d strip the ends. Remove the brad^et holding
the buzzer. Install the new buzzer with its mounting
bracket and lead, and connect the wires writh wire nuts.
Circuit Breaker
The 15-amp circuit breakers (two breakers in 208,240
volt, and one breaker in 220/380,24(^415 volt models)
on tile right side provide protection for the control dnajlt
and tile motor. The 50-amp breakers on the left are for
protection of the heating elements. The drcuit breakers
have an internal time delay. They detect a short circuit
or overload condition in the equipment and trip to the
OFF position.
TRANSFORMER
The control transformer is used to step down the
available supply voltage from 480 volts to 120 volts for
the use of the control and oven light drcuits. The jumper
straps (or wires) are used to set up the input and output
voltages to the required voltage. Rg. 4 is a schematic
showing the connection used. In replacing the old
transformer with the new one, take care to follow the
required connection accurately.
10

REPLACEMENT PARTS LIST (All Electric Ovens)
REPLACEMENT PARTS ORDERING
The following Information must accompany a replacement parts order or it cannot be filled.
A. Model and st^e or serial number.
B. Voltage and phase.
C. Appliance finish, permafinish, stainless steel, etc. (if applicadDle to part to be replaced).
This information can be found on the rating plate of the oven.
Parts may be ordered from your dealer, service agency, or the factory.
Orders to the factory shouid be addressed as shown below. Forf urther information concerning parts, ordering location,
contact:
Vulcan-Hart Company
3600 North Point Blvd.
Baltimore, MD 21222.
ALL SERVICE PERSONNEL
WHEN SERVICING THIS EQUIPMENT, USE ONLY
CONTROLS ORIGINALLY SUPPLIED ON THIS EQUIPMENT BY
VULCAN-HART COMPANY.
DO NOT SUBSTITUTE.
SUBSTITUTION OF CONTROLS AS STATED ABOVE
WILL AUTOMATICALLY VOID THIS WARRANTY
AND THE CERTIFICATION ASSOCIATED WITH THIS EQUIPMENT.
11