A. O. Smith DSE-10 Service Manual
Service Handbook
COMMERCIAL ELECTRIC WATER HEATERS
MODELS DSE-5 THRU DSE-120
SERIES 100 and 102
INSTALLATION CONSIDERATIONS - PRE SERVICE
CHECKS - WATER HEATER CONSTRUCTION -
500 Tennessee Waltz Parkway
Ashland City, TN 37015
OPERATION & SERVICE - TROUBLESHOOTING
SERVICING SHOULD ONLY BE PERFORMED BY A QUALIFIED SERVICE AGENT.
PRINTED IN THE U.S.A 1008 198335-000
1
COMMERCIAL ELECTRIC WATER HEATER
SERVICE MANUAL
TABLE OF CONTENTS
INTRODUCTION .......................................................................2
Qualifications......................................................................2
Service Warning .................................................................2
Tools Required....................................................................3
INSTALLATION CONSIDERATIONS........................................4
Closed Water Systems.......................................................4
Thermal Expansion.............................................................4
Electrical Requirements......................................................5
PRE SERVICE CHECKS...........................................................6
Service Precautions............................................................5
WATER HEATER CONSTRUCTION ........................................7
5 - 20 Gallon Models ..........................................................8
30 - 120 Gallon Models ......................................................9
OPERATION & SERVICE........................................................10
Principles of Electricity......................................................10
Single And Three Phase Power ....................................... 12
Checking Single Phase Power..................................13
Checking Three Phase Power...................................14
Fuses................................................................................15
Heating Elements ............................................................ 16
Heating Element Construction...................................16
Six and Three Wire Heating Elements ......................17
Single Phase Element Wiring.............................18 - 19
Three Phase Element Wiring..............................20 - 22
Heating Element Ratings & Configurations...............23
Heating Element Amperage Tables...........................24
Heating Element Amperage Test...............................25
Heating Element Voltage Test...................................26
Heating Element Resistance Tables..........................28
Heating Element Resistance Test..............................29
Heating Element Ground Test...................................30
Replacing Heating Elements.....................................31
Heating Element Sensors.................................................32
Element Sensor Operation........................................33
Contactors........................................................................34
Contactor Configurations...........................................35
Contactor Inspection..................................................36
Contactor Coil Voltage - At Contactor........................37
Contactor Coil Voltage - At CCB................................38
Transformers ....................................................................39
120 VAC Control Circuit Transformer Wiring.... 39 & 40
120 V AC Control Circuit Transformer Test.................41
24 VAC Transformer Test..........................................42
Immersion Temperature Probe.........................................43
Temperature Sensor Resist ance Test........................44
Temperature Sensor DC Vo ltage Test................. ... ...45
ECO Continuity Test..................................................45
ECO Voltage Test......................................................46
LWCO (Low Water Cut Off)..............................................47
Powered Anode Rod........................................................48
Electronic Controls ...........................................................49
CCB - Central Control Board.....................................50
CCB Socket & Wiring Terminal Identification ............51
CCB Enable Disable Circuit(s) Test...........................53
Checking Power And Ground To The CCB...............54
UIM - User Interface Module.....................................55
ELECTRONIC CONTROL SYSTEM.......................................56
Heating Element Operation..............................................56
Control System Features..................................................57
Control System Navigation...................................... ... ......57
The Desktop Screen.........................................................58
Status Icons...............................................................59
Operating States............................................ ............60
Control System Menus..............................................60
Temperatures Menu..........................................................61
Temperature Settings................................................62
Heater Status Menu..........................................................63
Economy Mode Setup Menu............................................64
Setpoint Adjustment Value........................................65
Time Clock Settings ..................................................66
Daily Operating Mode Settings..................................67
Alarm Output Setup Menu................................................68
Display Settings Menu......................................................69
Heater Information Menu..................................................70
Current Fault/Alert Menu..................................................71
Fault History Menu ............................ ... .. ..........................71
Fault Occurrence Menu...................................... ..............71
Restore Factory Defaults Menu........................................72
TROUBLESHOOTING.............................................................73
Common Service Problems..............................................73
Control System Diagnostics .............................................74
Fault Conditions ........................................................74
Alert Conditions.........................................................74
Resetting The Control System ..................................74
Control System Unresponsive....................................... ...74
UIM Display Is Blank.................................................74
UIM Is Inoperable......................................................75
Heating Cycle Disabled.............................................75
Fault & Alert Messages....................................................76
No Current Detected .................................................76
Temp Probe Open.....................................................77
Temp Probe Short.....................................................77
Energy Cut Out (ECO) ..............................................78
LWCO Fault...............................................................79
No Anode Current .....................................................80
INTRODUCTION
INTRODUCTION
This Service Manual is designed to be an aid in servicing and troubleshooting the
commercial electric water heater models listed on the cover .The instructions, illustrations
and procedures contained in this manual are used to verify proper operation and to
diagnose and repair common service problems.
This manual does not replace or supersede the Instruction Manual that came with the water
heater. Always refer to the Instruction Manual that came with the water heater for complete
installation instructions. If the Instruction Manual is not available copies can be obtained
from the manufacturers web site or by calling the technical support phone number shown on
the back cover of this manual.
Review the Common Service Problems on page 73 prior to performing any service
procedures.
QUALIFICATIONS - QUALIFIED SERVICE AGENT
Servicing the products referenced in this manual requires ability equivalent to that of a
Qualified Agency (as defined by ANSI below) in the field involved. Installation skills such as
plumbing, electrical supply are required in addition to diagnostic and electrical testing skills
when performing service.
ANSI Z223.1 2006 Sec. 3.3.83: “Qualified Agency” - “Any individual, firm, corporation or
company that either in person or through a representative is engaged in and is responsible
for (a) the installation, testing or replacement of gas piping or (b) the connection, installation,
testing, repair or servicing of appliances and equipment; that is experienced in such work;
that is familiar with all precautions required; and that has complied with all the requirements
of the authority having jurisdiction.”
SERVICE WARNING
If you are not qualified (as defined by ANSI above) and licensed or certified as required by
the authority having jurisdiction to perform a given task do not attempt to perform any of the
service, diagnostic or troubleshooting procedures described in this manual. If you do not
understand the instructions given in this manual or do not feel confident in your abilities to
perform a given task do not attempt to perform any procedures outlined in this manual.
IMPORTANT SERVICE REMINDER
When performing any troubleshooting step outlined in this manual always consider the
wiring and connectors between components. Perform a close visual inspection of all wiring
and connectors to and from a given component before replacement. Ensure wires were
stripped before being crimped in a wire connector. Ensure wires are crimped tightly in their
connectors. Ensure connection pins in sockets and plugs are not damaged or worn. Also
ensure plugs and sockets are mating properly and providing good contact.
Failure to perform this critical step or failing to perform this step thoroughly often results in
needless down time, unnecessary parts replacement, and customer dissatisfaction.
Servicing should only be performed by a Qualified Service Agent
2
INTRODUCTION
INSTRUCTION MANUAL
Have a copy of the Instruction Manual that came with the water heater on hand for the
correct model water heater you are working with before servicing.
Installation information given in this Service Manual IS NOT a complete installation
instruction. Installation information covered in this Service Manual has a limited focus as it
applies to servicing. This Service Manual does not replace or supersede the Instruction
Manual that came with the water heater. Always refer to the Instruction Manual that came
with the water heater for complete installation instructions.
If the Instruction Manual is not on hand copies can be obtained from the manufacturers web
site or by calling the technical support phone number shown on the water heater labeling
and the back cover of this Service Manual.
TOOLS REQU IRED
• Instruction Manual that came with the water heater.
• All tools common to installation and service of commercial water heaters such as hand
tools, torch, pipe wrenches etc.
• Electrical switch lock out device - used to secure disconnect switches/breaker panels
while servicing.
• Insulated fuse puller(s).
• Adhesive numbered/colored wire markers - 3M Scotch Code SDR0-9 Numbered Wire
Markers; 3M Scotch Code STD-C Colored Wire Markers or equivalent.
• Volt-Ohm Multi Meter - recommend Fieldpiece HS36, Fluke 187, UEI model DL289 or
equivalent capable of measuring:
• AC Voltage up to 600 VAC
• DC Voltage up to 24 VDC
• Ohms up to 2,000,000 ohms
• AC amp meter - recommend UEI model DL289 or equivalent capable of measuring:
• AC amperage up to 400 amps
Servicing should only be performed by a Qualified Service Agent
3
INSTALLATION CONSIDERATIONS
INSTALLATION CONSIDERATIONS
Installation information given in this Service Manual IS NOT a complete installation
instruction. Installation information covered in this Service Manual has a limited focus as it
applies to servicing. This Service Manual does not replace or supersede the Instruction
Manual that came with the water heater. Always refer to the Instruction Manual that came
with the water heater for complete installation instructions.
If the instruction Manual that came with the water heater is not on hand copies can be
obtained from the manufacturers web site or by calling the technical support phone number
shown on the water heater labeling and the back cover of this Service Manual.
CLOSED WATER SYSTEMS
Water supply systems may, because of code requirements or such conditions as high line
pressure, among others, have installed devices such as pressure reducing valves, check
valves, and back flow preventers. Devices such as these cause the water system to be a
closed system.
Virtually all commercial and most residential water supply systems are closed systems
today. Closed water systems will experience thermal expansion which, if not controlled with
a properly installed and sized thermal expansion tank, can cause premature failure
(leakage) of the water heater. Water heater failure (leakage) on closed systems where there
is not a thermal expansion tank installed is not covered under the limited warranty.
THERMAL EXPANSION
As water is heated, it expands (thermal expansion). In a closed system the volume of water
will grow when it is heated. As the volume of water grows there will be a corresponding
increase in water pressure due to thermal expansion. Thermal expansion can cause
premature tank failure (leakage). This type of failure is not covered under the limited
warranty. Thermal expansion can also cause intermittent temperature-pressure relief valve
operation: water discharged from the valve due to excessive pressure build up. This
condition is not covered under the limited warranty. The temperature-pressure relief
valve is not intended for the constant relief of thermal expansion.
A properly sized thermal expansion tank should be installed on all closed systems to control
the harmful effects of thermal expansion.
Servicing should only be performed by a Qualified Service Agent
4
INSTALLATION CONSIDERATIONS
ELECTRICAL REQUIREMENTS
Grounding
Review the electrical ground requirements given in the Instruction Manual that came with
the water heater and ensure the water heater has been properly grounded.
The water heater must be grounded in accordance with the National Electric Code and/or
local codes. These codes must be followed in all cases.
The water heater must be connected to a grounded metal, permanent wiring system; or an
equipment grounding conductor must be run with the circuit conductors and connected to
the equipment grounding terminal or lead on the water heater.
Service Note: The water heaters covered in this manual are equipped with electronic
controls that may experience erratic operation if the water heater is not properly grounded.
These water heaters are also equipped with a LWCO (low water cut off). Some models will
also be equipped with a powered anode rod. LWCO devices and powered anode rods
require an adequate earth ground to work properly. See pages 47 and 48.
Power Supply
Review the electrical requirements listed on the water heater’s rating label and in the
Instruction Manual that came with the water heater. Ensure the branch circuit supplying
power to the water heater is within these requirements and properly connected.
Ensure the power supply phase (single or three phase / 1Ø, 3Ø) and power supply voltage
match the water heater’s rating label. Some of the commercial electric water heater models
covered by this Service Manual are phase convertible. Voltage and KW conversions ARE
NOT permitted.
Servicing should only be performed by a Qualified Service Agent
5
PRE SERVICE CHECKS
WIRING CONNECTIONS
With the power supply to the water heater turned off ensure the wiring connections are
properly tightened to all components including: high voltage terminal blocks, fuse blocks,
contactors and transformers.
Loose connections at any connection point will cause increased amperage and excessive
heat which can damage wiring and components. Whenever worn or damaged wiring and
components must be replaced ensure all wiring connections are properly tightened before
putting the water heater back in service.
SERVICE PRECAUTIONS
1 DO NOT energize the branch circuit supplying power to the water heater or test the
water heater electrical system before the water heater is completely filled with water.
Read the start up procedures in the Instruction Manual that came with the water heater.
2 Be sure to turn off power and use a lock out device at the branch circuit power supply
disconnect switch or breaker when servicing the electrical system of the water heater.
Never touch electrical components with wet hands or when standing in water.
PRE SERVICE CHECKS
3 When replacing heating elements ensure they are rated at the correct voltage and KW
for the water heater being serviced see pages 23 and 31.
4 When replacing fuses use an insulated fuse puller to remove and install fuses. Always
use the correct size for the circuit. See the Instruction Manual that came with the water
heater for fuse size requirements. See page 15 in this manual.
5 Using an AC volt meter measure the branch circuit power supply voltage to the water
heater. Ensure the measured voltage of the branch circuit supplying power to the water
heater matches the water heater’s rating label - see pages 12 - 14.
6 Ensure the phase of the branch circuit supplying power to the water heater matches the
water heater’s rating label. Some water heater models covered by this Service Manual
are phase convertible. Some models are not phase convertible. See the Instruction
Manual that came with the water heater for more information on phase conversions.
7 The water heaters covered by this manual have a multi tap control circuit transformer.
This is a step down transformer that outputs 120 V AC (secondary winding) which is used
to power the electronic control system and energize the contactor coils. The transformer
can accommodate different power supply voltages and has multiple input voltage
connections or “taps.” Ensure the input supply voltage (primary winding) wiring to the
transformer is connected properly. See the Instruction Manual that came with the water
heater and pages 39 & 40 in this manual for more information.
Service Note - Contactor Chatter: Incorrect supply voltage wiring to the multiple tap 120
VAC Control Circuit Transformer will cause low/high output voltage from the transformer.
This can cause contactors to open and close their contacts rapidly (contactor chatter) and
result in permanent damage to the contactors. See pages 39 & 40.
Servicing should only be performed by a Qualified Service Agent
6
WATER HEATER CONSTRUCTION
WATER HEATER CONSTRUCTION
Electronic Controls
The water heaters covered in this Service Manual are equipped with an electronic control
system - see page 56. The control system senses temperature electrically from an
Immersion Temperature Probe. The probe is installed in a threaded opening in the storage
tank (wet well) and senses water temperature directly . As the stored water temperature rises
and falls the control system de-energizes and energizes heating elements indirectly using
electromagnetic contactors. The control system energizes the electromagnetic contactor’s
(120 VAC) coil causing the switch contacts of the contactor to close which in turn supplies
power to the heating elements - see pages 34 - 38.
Heating Element Configurations
Depending on tank size and how they were ordered from the factory the water heaters
covered in this Service Manual may be equipped with 1 to 5 electric heating elements. Tot al
input KW ranges from 3KW to 90KW. The water heaters covered in this manual are
available in storage tanks sizes from 5 to 120 gallons.
Power Conversions
Other than power supply phase conversions on some models the water heaters covered in
this Service Manual cannot be field converted. Voltage and KW conversions ARE NOT
permitted. See the Instruction Manual that came with the water heater for more information.
If the Instruction Manual is not available copies can be obtained from the manufacturers web
site or by calling the technical support phone number shown on the water heater labeling
and the back cover of this Service Manual.
Servicing should only be performed by a Qualified Service Agent
7
5 - 20 GALLON MODELS
Figure 1
WATER HEATER CONSTRUCTION
Servicing should only be performed by a Qualified Service Agent
8
WATER HEATER CONSTRUCTION
Figure 2
30 - 120 GALLON MODELS
Servicing should only be performed by a Qualified Service Agent
9
OPERATION & SERVICE
This section of the manual will cover principles of electricity, single and three phase power,
fuses, heating element construction & operation, heating element sensors, contactors,
common service procedures and more. Information and service procedures presented in
this section will be referenced in the troubleshooting sections at the end of this manual.
PRINCIPLES OF ELECTRICITY
Voltage
The unit of measurement used to quantify electrical pressure or the force that causes
electrical energy to flow is the volt or voltage. V olt meters are used to determine if there is an
adequate supply of electricity or voltage to a heating element.
Amperage
The unit of measurement used to quantify the rate at which electrical current is flowing is the
ampere or amp. Amp meters are used to determine if a heating element is working - if there
is adequate current flowing through the heating element.
Ohms
The unit of measurement used to quantify the opposition or “resistance” to the flow of
electricity is the ohm. As resistance (ohms) in an electrical circuit increases current
(amperage) will decrease and as resistance decreases current will increase. Ohm meters
are used for measuring the resistance of heating elements, for open circuit continuity tests
on heating elements and for shorted to ground continuity tests on heating elements.
OPERATION & SERVICE
Service Note: Volt, ohm and amp meter test instruments are necessary to perform the
service and diagnostic procedures outlined in this manual - see Tools Required on page 3.
Wattage
The unit of measurement used to quantify the rate or amount of electrical energy being used
is the watt. One thousand watts is referred to as one kilowatt. Heating elements are rated in
kilowatts expressed as KW. The higher the kilowatt rating of a heating element the more
power it will use and the more heat it will generate. One kilowatt generates 3412 Btu of heat.
Servicing should only be performed by a Qualified Service Agent
10
OPERATION & SERVICE
Ohms Law
A law that explains the relationship between voltage, current and resistance. The law states
that the electric current flowing through a conductor is equal to the voltage divided by the
resistance. The following equations further explain ohms law.
V=Volts (electrical pressure)
A=Amps (electrical flow/current)
O=Ohms (resistance to electrical flow/current)
W=Watts (rate or amount of electricity used)
Ohms Law applied to single phase power - each loop of a six wire element:
V ÷ A = O W ÷ V = A V ÷ O = A V x A = W A x O = V W ÷ A = V
Ohms Law applied to three phase power - each wiring lead to a three wire element:
0.577 x W ÷ V = A V x A x 1.73 = W
Service Note: See Heating Element Ratings on page 23 to determine the voltage and KW
rating of a heating element.
Servicing should only be performed by a Qualified Service Agent
11
OPERATION & SERVICE
277 Volt 1Ø Power
208/240/480 Volt 1Ø Power
208/240/480 Volt 3Ø Power
Power Distribution Block
Models with more than one heating element only.
See Figures 1 & 2 on pages 8 and 9.
SINGLE AND THREE PHASE POWER
These water heaters can be factory ordered for standard: 277/208/240/480 volt power. 277
volt models are single phase only - other voltages may be single or three phase.
Field Conversions
Some water heaters may be converted for single or three phase power within the guidelines
listed below. Follow the phase conversion instructions provided in the Instruction manual
that came with the water heater. Voltage/KW conversions ARE NOT permitted.
• 208/240 VAC models factory configured 24KW or less are convertible as single or three phase and
include jumpers to make the conversion.
• 208/240 VAC models factory configured as single phase with over 24KW can be converted to three
phase but jumpers are not provided.
• 208/240 VAC models factory configured as three phase with over 24KW cannot be converted to
single phase.
• No 480 VAC models are phase convertible.
• Heating element voltage and KW conversions are not permitted on any models.
V erifying the power supply is correct is typical first step during most service procedures. The
illustrations and instructions on the following pages will outline how this is done.
Servicing should only be performed by a Qualified Service Agent
12
OPERATION & SERVICE
277 Volt 1Ø Power
208/240/480 Volt 1Ø Power
Power Distribution Block
L1 L2
3 Pole Contactor
4 Pole Contactor
Measure power supply
voltage to water heater
on single element models
at upper terminals of the
contactor.
Measure power supply
to heating elements on
all models at the lower
terminals of the
contactor(s).
Measure power supply
voltage to water heater
on models with more
than one element at the
Power Distribution Block
Checking Single Phase (1Ø) Power
A single phase power supply will be connected to the L1 and L2 terminals of the Power Distribution
Block or directly to the contactor on models equipped with a single element. On 208/240/480 volt
power supplies both wires are “hot” with voltage present. On a 277 volt power supply one of the two
wires is a “neutral” and does not have any voltage present. Check power supply voltage as follows:
1 With the power supply to the water heater turned on set the volt meter to an AC volt age range above the
expected voltage (600 VAC or higher range initially).
2 Measure and record voltage between the [L1 & L2] ter minals at the water heater’s Power Distribution Bl ock
or at the contactor on a single element model. Models equipped with a single element and a 4 pole
contactor will require two voltage readings; one voltage reading between the first and second terminals of
the contactor and a second voltage reading between the third and fourth terminals of the contactor.
3 Measure and record the voltage between the L1 terminal and the ground wire connection to the water
heater. Ch eck between L2 and g round in the sam e way. Note: models equippe d with a single element and
a 4 pole contactor will require four voltage readings; between the each of the 4 poles of the contactor and
ground. On 208/240 volt power supplies each reading to ground should be approximately 120 volts. On
480 volt power supplies each reading to ground should be appr oximately 277 volts. On 277 volt power on e
of the wires is a neutral wire and will normally read approximately zero volts to ground.
Service Warning: Zero volt readings between terminals and ground can be due to an inadequate earth
ground. TREAT ALL WIRES AS BEING HOT until it has been determined there is no voltage present.
If the voltage readings between terminals (step 2) or the voltage between any of the terminals and
ground (step 3) was less than expected (< 95% expected): check the power supply to the water
heater. Contact a Qualified/Licensed electrician to restore power. If the voltage readings taken in
Step 2 above are a standard voltage (277/208/240/480) but do not match the listed voltage on the
water heater’s rating label secure power to the water heater. DO NOT place the water heater back in
service. Call the toll free Technical Support phone number listed on the b ack cover of this manual for
further assistance.
Servicing should only be performed by a Qualified Service Agent
13
OPERATION & SERVICE
208/240/480 Volt 3Ø Power
L1 L2 L3
Power Distribution Block
3 Pole Contactor
4 Pole Contactor
Measure power supply
voltage to water heater
on single element models
at upper terminals of the
contactor.
Measure power supply
voltage to water heater
on models with more
than one element at the
Power Distribution Block
Measure power supply
to heating elements on
all models at the lower
terminals of the
contactor(s).
Checking Three Phase (3Ø) Power
A three phase power supply will be connected to the L1, L2 and L3 terminals of the Power
Distribution Block or directly to the contactor on models equipped with a single element. All three
wires are “hot” with voltage present. Check power supply voltage as follows:
1 With the power supply to the water heater turned on set the volt meter to an AC volt age range above the
expected voltage (600 VAC or higher range initially).
2 Measure and record the voltage at the water h eater’s Power Distribution Block or at the cont actor on single
element models. Measure voltage between; [L1 & L2], [L2 & L3] and [L1 & L3] terminals. This will be three
voltage readings at a Power Distribution Block or a 3 pole cont actor . Models eq uipped with a single heating
element and a 4 pole contactor will require taking the voltage readings between the [L1 & L2] and [L2 & L3]
terminals twice since there are two L2 terminals on th e contactor - total of 4 voltage readings. All voltage
readings should be approximately the same .
3 Measure and record the voltage between the L1 terminal and the ground wire connection to the water
heater. Ch eck betwe en L2 and gr ound and L3 and ground in the same way. Note: models equipped with a
single element and a 4 pole contactor will require four voltage readings; between the each of the 4 poles of
the contactor and ground. On some 208 volt power supplies each reading to ground will be approximately
120 volts. Some 208 volt models will have a “stinger leg” with one of the three readings to ground
measuring 208 volts - 208 volt stinger legs should be connected to L2. On 240 volt power supplies each
reading to ground should be approximately 120 volts. On 480 volt power supplies each reading to ground
should be approximately 277 volts.
Service Warning: Zero volt readings between terminals and ground can be due to an inadequate earth
ground. TREAT ALL WIRES AS BEING HOT until it has been determined there is no voltage present.
If the voltage readings between terminals (step 2) or the voltage between any of the terminals and
ground (step 3) was less than expected (< 95% expected): check power supply fuses, the breaker
and/or disconnect switch supplying power to the water heater. Contact a Qualified/Licensed
electrician to restore power. If the voltage readings taken in Step 2 above are a standard voltage
(208/240/480) but do not match the listed voltage on the water heater’s rating label secure power to
the water heater . DO NOT place the water heater back in se rvice. Call the toll free Technical Support
phone number listed on the back cover of this manual for further assistance.
Servicing should only be performed by a Qualified Service Agent
14
OPERATION & SERVICE
Volt Meter MethodOhm Meter Method
FUSES
Depending on total amp draw and how they were ordered some water heaters will be
equipped with power circuit fuses to protect the heating element circuits. All models will have
two fuses to protect the primary winding of the 120 Volt Control Circuit Transformer. See
Figures 1 and 2 on pages 8 and 9 for location. Testing fuses requires an ohm meter, an AC
volt meter and an insulated fuse puller - see Tools Required page 3.
Service Note - Replacement Fuses: Replacement fuses MUST BE of the same value and
type as the factory installed fuses - call the toll free technical support or parts department
phone number on the back cover of this manual for further assistance.
Ohm Meter Method
1 Secure power to the water heater at the main breaker or disconnect switch.
2 Remove each fuse to be tested with an insulated fuse puller.
3 Set the Ohm meter to it’s lowest resistance range (< 20 0) or to an audible be ep continuity test setting if
so equipped.
4 Touch the meter probes to both ends of each fuse simultaneously.
5 If the fuse being tested shows a low resistance (< 1 ohms) or the continuity test feature sounds an
audible beep the fuse being tested is good and can be re-installed.
6 If the fuse being tested shows infinite resistance (open circuit) or the continuity test feature does not
sound an audible beep the fuse being tested is blown and must be replaced.
Volt Meter Method
Fuses can also be checked using an AC volt meter. The power supply must be turned on
and a call for heat must be active (all contactors must be closed) during this test. Touch the
two test probes to both ends of each fuse while still in the fuse blocks.
• A high voltage (at or above 120 VAC) reading indicates the fuse is blown.
• A zero volt reading generally indicates the fuse is goo d. Next check for voltage betwee n each end of the fuse
and ground to ensure voltage is pre sent at both ends of the fuse. If no volt age is present b etween either e nd
of the fuse and ground the test has not been conclusive - secure power to the wate r heater and per form th e
ohm meter test method described above.
The voltage test method is a good way to quickly identify fuses that are blown but it is not
always conclusive due to the dependence on power being present at both ends of the fuse,
all contactors being closed and correct wiring. Keep this in mind as there may be times when
a fuse that is blown tests good due to one of these dependencies not being met. The ohm
meter method described above may be more time consuming but it is 100% conclusive.
Servicing should only be performed by a Qualified Service Agent
15
OPERATION & SERVICE
Top View
Heating Element Flange - End View
Side View
Resistive Circuits
Three resistive wire conductors inside three U shaped loops that are
permanently fitted into a flange form the heating element.
Internal View - U Shaped Loop
Six or Three Wire Leads
Three U shaped loops enclose wire conductors
that are surrounded by an insulating material.
Heating Element Flange
Two ends
of loop 1
Two ends
of loop 2
Two ends
of loop 3
HEATING ELEMENTS
Heating Element Construction
The water heaters covered in this manual use electric heating elements to heat water.
Heating elements convert electrical energy into heat energy.
Heating elements are constructed using 3 tubes formed into U shaped loops. The two ends
of each loop are permanently fitted into the element flange. Inside each loop is a wire
conductor (a resistive electrical circuit) surrounded by an insulating material. These wire
conductors pose a relatively high resistance to the flow of electricity . Heat is generated when
the electricity (voltage) applied to the element begins to flow (amperage) and encounters the
resistance (ohms) of the wire conductors inside. See “Principles of Electricity” on page 10.
There are two types of heating elements installed in the water heaters covered in this
manual; one type has six wire leads and the other has three wire leads. Heating elements
with six wire leads are installed on water heaters configured for single phase and three
phase power. Heating elements with three wire leads (Y configured) are installed on water
heaters configured for three phase power only. See “Single And Three Phase Power” on
page 12 and “Heating Element Wiring” section between pages 17 - 22.
Servicing should only be performed by a Qualified Service Agent
16
OPERATION & SERVICE
Six wiring leads,
one at both ends
of each loop.
Three wiring leads,
one at one end
of each loop.
Metal bar that joins
or splices together
one end of each loop.
Six Wire Element
Single & Three Phase Power
Three Wire Element - Y Configured
Three Phase Power Only
Metal bar that joins
or splices together
one end of each loop.
Three wiring leads.
Six wiring leads.
Heating Element Wiring
This section will provide more detailed information on heating elements and how they are
wired in single phase, three phase Delta and three phase Y configurations. See “Single And
Three Phase Power” on page 12.
Six and Three Wire Heating Elements
Depending on how a water heater is ordered and factory configured it will be equipped with
heating elements that have six wiring leads or three wiring leads. Six wire elements can be
used with single or three phase power. Three wire (also called Y configured) heating
elements are used with three phase power only.
Each heating element has 3 loops, each loop is a resistive circuit see “Heating Element
Construction” on page 16. Six wire heating elements have a wire lead connected to both
ends of the three loops. Three wire heating elements (Y configured) have a metal bar that
joins or splices together one end from each of the three loops and a wire lead connected to
the remaining end of each loop. See the illustrations below.
See also pages 18 - 22 for details on wiring between the heating elements and contactors.
Servicing should only be performed by a Qualified Service Agent
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OPERATION & SERVICE
Heating Element Flange - End View
Two ends
of loop 1
Two ends
of loop 2
Two ends
of loop 3
Connection Diagram Wiring Diagram
3 Pole
Contactor
Three loops
of one heating element
Single phase (1Ø)
power supply
Note: these two lines
exiting the bottom
of the contactor
represent six
wiring leads from
a heating element
as shown in the
connection diagram
on the left.
Note: middle pole
of the three pole
contactor is not used
on models configured
for single phase (1Ø
power.
Single Phase Wiring - 3 Pole Contactor
The illustrations below show how six wire heating elements (page 17) are wired to 3 pole
contactors on water heaters connected to a single phase power supply. See the
“Contactors” section of this manual - pages 34 - 38.
Servicing should only be performed by a Qualified Service Agent
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OPERATION & SERVICE
Heating Element Flange - End View
Two ends
of loop 1
Two ends
of loop 2
Two ends
of loop 3
Connection Diagram Wiring Diagram
4 Pole
Contactor
Three loops
of one heating element
Single phase (1Ø)
power supply
Models configured for
single phase power (1Ø)
and equipped with 4 pole
contactors will have two
jumper wires. One
between the 1st and 3rd
poles of the contactor
and one between the 2nd
and 4th poles of the
contactor.
Single Phase Wiring - 4 Pole Contactor
The illustrations below show how six wire heating elements (page 17) are wired to 4 pole
contactors on water heaters connected to a single phase power supply. See the
“Contactors” section of this manual - pages 34 - 38.
Servicing should only be performed by a Qualified Service Agent
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OPERATION & SERVICE
Heating Element Flange - End View
Two ends
of loop 1
Two ends
of loop 2
Two ends
of loop 3
Connection Diagram Wiring Diagram
3 Pole
Contactor
Three loops
of one heating element
Note: each line
from the bottom
of the contactor
represents two
wiring leads from
a heating element
as shown in the
connection diagram
on the left.
Three phase (3Ø)
power supply
Three Phase Delta Wiring - 3 Pole Contactor
The illustrations below show how six wire heating elements (page 17) are wired to 3 pole
contactors on water heaters connected to a three phase power supply. See the “Contactors”
section of this manual - pages 34 - 38.
Servicing should only be performed by a Qualified Service Agent
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OPERATION & SERVICE
Heating Element Flange - End View
Two ends
of loop 1
Two ends
of loop 2
Two ends
of loop 3
Connection Diagram Wiring Diagram
4 Pole
Contactor
Three loops
of one heating element
Three phase (3Ø)
Models configured for
power supply
three phase power (3Ø)
and equipped with 4 pole
contactors will have a
jumper wire between the
2nd and 3rd poles of
the contactor.
Three Phase Delta Wiring - 4 Pole Contactor
The illustrations below show how six wire heating elements (page 17) are wired to 4 pole
contactors on water heaters connected to a three phase power supply. See the “Contactors”
section of this manual - pages 34 - 38.
Servicing should only be performed by a Qualified Service Agent
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OPERATION & SERVICE
Heating Element Flange - End View
Two ends
of loop 1
Two ends
of loop 2
Two ends
of loop 3
Connection Diagram Wiring Diagram
3 Pole
Contactor
Three loops
of one heating element
Three phase (3Ø)
power supply
Metal bar that joins
or splices together
one end of each loop.
Wiring leads from
heating element
Metal bar that joins
or splices together
one end of each loop.
Three Phase Y Configuration - 3 Pole Contactor
The illustrations below show how three wire (Y configured) heating elements (page 17) are
wired to 3 pole contactors on water heaters connected to a three phase power supply. See
the “Contactors” section of this manual - pages 34 - 38.
Servicing should only be performed by a Qualified Service Agent
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OPERATION & SERVICE
Heating Element Flange
3 1 - 3,000
6 1 - 6,000
9 1 - 9,000
12 1 - 12,000
15 1 - 15,000
18 1 - 18,000
*18 2 - 9,000
24 2 - 12,000
30 2 - 15,000
36 2 - 18,000
*36 3 - 12,000
45 3 - 15,000
54 3 - 18,000
**60 4 - 15,000
**75 5 - 15,000
**90 5 - 18,000
NUMBER
OF ELEMENTS
AND WATTAGE
* 208 Vol t models use one addition al element.
** Only Available in 50 gallon models or larger.
STANDARD
KW INPUT
RATINGS
Heating Element Ratings
There are six “standard” heating element KW ratings used; 3, 6, 9,
12, 15 and 18KW . Heating element flanges are stamped with the part
number, voltage and KW rating - see the illustration to the right.
Heating Element Configurations
The table below shows standard heating element configurations
used. Keep in mind the water heaters covered by this service manual
can be custom ordered with heating element voltage and KW ratings
other than what is shown in this table. Always check the water
heater’s rating label to see how the water heater was configured at the factory.
Service Note: Models at 54 KW and above are not available in 208 single phase (1Ø)
configurations. Also notice that some 208 volt models will contain additional elements.
Servicing should only be performed by a Qualified Service Agent
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OPERATION & SERVICE
208 VAC 240 VAC 277 VAC 480 VAC
3,000 1,000 4.81 4.17 3.61 2.08
,
9,000
,
3
,
4
18,000
6,000 28.85 25.00 21.66 12.50
TOTAL
ELEMENT
WATTAGE
PE R LOOP
APPROXIMATE AMPS THROUGH EACH LOOP
SIX WIRE ELEMENT TABLE
20 8 VAC 240 VAC 4 80 VAC
3,000 8.32 7.21 3.61
,
12,000 33.29 28.85 14.43
18,000
49.93 43.28 21.64
TOTAL
ELEMENT
WATTAGE
APPROXI MATE A MPS THROUGH EACH WIRE
3 WIRE (Y CONFIGURED) ELEMENT TABLE
Heating Element Amperage - Six Wire Elements
The table below shows the approximate amp draw through each loop (see page 17) of a six
wire heating element. First determine the actual rated wattage and voltage of the element
being tested - see page 23. Then follow the Heating Element Amperage Test procedure on
page 25 to measure amperage through each loop of the six wire heating element being
tested. The 3 amp readings, one for each loop, should be approximately the same. Compare
the measured values to the values in the table below. Keep in mind there may be some
variance between measured values and the values in this table due to fluctuations in
voltage, temperature and the calibration of test instruments being used.
WATTAGE
6,000
12
000 4,000 19.2
15,000
000 9.62 8.33 7.22 4.17
2
3,000 14.42 12.50 10.83 6.25
16.67 14.44 8.33
000 24.0
5
20.83 18.05 10.42
Heating Element Amperage - Three Wire (Y Configured) Elements
The table below shows the approximate amp draw through each wire (see page 17) of a
three wire heating element. First determine the actual rated wattage and voltage of the
element being tested - see page 23. Then follow the Heating Element Amperage test
procedure on page 25 to measure amperage through each wire of the three wire heating
element being tested. The 3 amp readings should be approximately the same. Compare the
measured values to the values in the table below . Keep in mind there may be some variance
between measured values and the values in this table due to fluctuations in voltage,
temperature and the calibration of test instruments being used.
6,000 16.64 14.43 7.21
9
000 24.97 21.64 10.82
15,000 41.61 36.06 18.03
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