A. O. Smith DSED-10, DSED-120 Installation Manual

COMMERCIAL ELECTRIC WATER HEATERS

A DIVISION OF A. O. SMITH CORPORATION

RENTON, WASHINGTON

www.hotwater.com

ASME

Instruction Manual

MODELS DSED 5 THRU DSED 120

FOR DEIONIZED WATER ONLY

INSTALLATION - OPERATION - SERVICE -

MAINTENANCE - LIMITED WARRANTY

Thank you for buying this energy efficient water
heater. We appreciate your confidence in our
products.

PLACE THESE INSTRUCTIONS ADJACENT TO WATER HEATER AND NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE.

PRINTED 0110 317651-000

SAFE INSTALLATION, USE AND SERVICE

Your safety and the safety of others is extremely important in the installation, use, and servicing of this water heater.

Many safety-related messages and instructions have been provided in this manual and on your own water heater to warn you and
others of a potential injury hazard. Read and obey all safety messages and instructions throughout this manual. It is very important
that the meaning of each safety message is understood by you and others who install, use, or service this water heater.

This is the safety alert symbol. It is used to alert
you to potential personal injury hazards. Obey all
safety messages that follow this symbol to avoid
possible injury or death.

DANGER indicates an imminently hazardous

DANGER

WARNING

CAUTION

situation which, if not avoided, will result in
death or injury.

WARNING indicates a potentially hazardous
situation which, if not avoided, could result in
death or injury.

CAUTION indicates a potentially hazardous
situation which, if not avoided, could result in
minor or moderate injury.

CAUTION used without the safety alert symbol

CAUTION

All safety messages will generally tell you about the type of hazard, what can happen if you do not follow the safety
message, and how to avoid the risk of injury.

The California Safe Drinking Water and Toxic Enforcement Act requires the Governor of California to publish a list of
substances known to the State of California to cause cancer, birth defects, or other reproductive harm, and requires
businesses to warn of potential exposure to such substances.

This product contains a chemical known to the State of California to cause cancer, birth defects, or other reproductive
harm. This appliance can cause low level exposure to some of the substances listed in the act.

• QUALIFIED INSTALLER OR SERVICE AGENCY:

Installation and service of this water heater requires ability equivalent to that of a Qualied Agency (as dened by ANSI below) in

the eld involved. Installation skills such as plumbing and electrical supply are required in addition to electrical testing skills when

performing service.

• ANSI Z223.1 2006 Sec. 3.3.83:

“Qualied Agency” - “Any individual, rm, 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.”

indicates a potentially hazardous situation
which, if not avoided, could result in property
damage.

IMPORTANT DEFINITIONS

If you are not qualied (as dened by ANSI above) and licensed or certied as required by the authority having jurisdiction to perform a

given task do not attempt to perform any of the procedures described in this manual. If you do not understand the instructions given in
this manual do not attempt to perform any procedures outlined in this manual.

2

GENERAL SAFETY INFORMATION

PRECAUTIONS

DO NOT USE THIS APPLIANCE IF ANY PART HAS BEEN UNDER

WATER. Immediately call a qualied service technician to inspect

the appliance and to replace any part of the control system which
has been under water.

If the unit is exposed to the following, do not operate heater until all

corrective steps have been made by a qualied service agency.

1. External re.

2. Damage.

3. Firing without water.

GROUNDING INSTRUCTIONS

This water heater must be grounded in accordance with the National
Electrical Code and/or local codes. These must be followed in all cases.
Failure to ground this water heater properly may also cause erratic
control system operation on ELECTRONIC CONTROL models.

This 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.

When servicing this unit, verify the power to the unit is turned off prior to opening the control cabinet door.

HYDROGEN GAS (FLAMMABLE)

Hydrogen gas can be produced in a hot water system served by this water

heater that has not been used for a long period of time (generally two weeks
or more). Hydrogen gas is extremely ammable. To reduce the risk of injury

under these conditions, it is recommended that the hot water faucet be
opened for several minutes at the kitchen sink before using any electrical
appliance connected to the hot water system. If hydrogen gas is present
there will probably be an unusual sound such as air escaping through the

pipe as water begins to ow. THERE SHOULD BE NO SMOKING OR

OPEN FLAME NEAR THE FAUCET AT THE TIME IT IS OPEN.

3

TABLE OF CONTENTS

SAFE INSTALLATION, USE AND SERVICE...........................................................2

GENERAL SAFETY INFORMATION .......................................................................3

Precautions ....................................................................................................3

Hydrogen Gas (Flammable) ...........................................................................3

TABLE OF CONTENTS ...........................................................................................4

INTRODUCTION .....................................................................................................4

Preparing for the Installation ..........................................................................4

DIMENSIONS AND CAPACITIES DATA .................................................................5

FEATURES AND COMPONENTS ..........................................................................6

APPROVALS ...........................................................................................................7

MODEL AND RATING .............................................................................................7

LOCATING THE NEW WATER HEATER ................................................................7

Facts to Consider About the Location ............................................................7

INSTALLATION REQUIREMENTS .........................................................................8

Required Ability ..............................................................................................8

General ..........................................................................................................8

Contaminated Water ......................................................................................8

Circulating Pump ............................................................................................8

Temperature-Pressure Relief Valve................................................................8

Water Line Connections .................................................................................9

Closed Water Systems ...................................................................................9

Thermal Expansion ........................................................................................9

ELECTRICAL DATA ...............................................................................................10

General ........................................................................................................10

Branch Circuit ...............................................................................................10

Heater Circuits .............................................................................................10

Control Circuits .............................................................................................10

Power Circuit ................................................................................................10

WIRING DIAGRAMS .............................................................................................12

OPERATION- ........................................................................................................15

General ........................................................................................................15

Filling the Water Heater ................................................................................15

Initial Start Up ...............................................................................................15

Draining the Water Heater ............................................................................15

TEMPERATURE REGULATION ...........................................................................16

High Temperature Limit Controls (ECO) .......................................................16

Thermostat Controls .....................................................................................16

Temperature Adjustment ..............................................................................16

CONTROL SYSTEM OPERATION .......................................................................17

Heating Element Operation ..........................................................................17

Control System Features .............................................................................17

Control System Navigation ...........................................................................17

The Desktop Screen ....................................................................................17

Temperatures Menu .....................................................................................20

Heater Status Menu .....................................................................................22

Economy Mode Settings ..............................................................................24

Alarm Output Setup Menu ............................................................................27

Display Settings Menu .................................................................................27

Heater Information Menu .............................................................................27

Current Fault/Alert Menu ..............................................................................28

Fault History Menu .......................................................................................28

Fault Occurrence Menu ................................................................................28

Restore Factory Defaults Menu ...................................................................29

MAINTENANCE ....................................................................................................30

General ........................................................................................................30

Temperature-Pressure Relief Valve Operation .............................................30

Flushing ........................................................................................................30

Sediment Removal .......................................................................................30

Lime Scale Removal ....................................................................................31

TROUBLESHOOTING CHECKLIST .....................................................................32

Not Enough or No Hot Water .......................................................................32

Hard Water ...................................................................................................32

Water is Too Hot ...........................................................................................32

Water Heater Makes Strange Sounds ..........................................................32

Leakage Checkpoints ...................................................................................32

WARRANTY ..........................................................................................................33

INTRODUCTION

Thank You for purchasing this water heater. Properly installed and
maintained, it should give you years of trouble free service.

ABBREVIATIONS USED

Abbreviations found in this Instruction Manual include:

• ANSI - American National Standards Institute

• ASME - American Society of Mechanical Engineers

• GAMA - Gas Appliance Manufacturer’s Association

• NEC - National Electrical Code

• NFPA - National Fire Protection Association

• UL - Underwriters Laboratory

• CSA - Canadian Standards Association

PREPARING FOR THE INSTALLATION

1. Read the “General Safety” section of this manual rst and then

the entire manual carefully. If you don’t follow the safety rules,
the water heater may not operate safely. It could cause DEATH,
SERIOUS BODILY INJURY AND/OR PROPERTY DAMAGE.

This manual contains instructions for the installation, operation,

and maintenance of the electric water heater. It also contains
warnings throughout the manual that you must read and be
aware of. All warnings and all instructions are essential to the
proper operation of the water heater and your safety. READ
THE ENTIRE MANUAL BEFORE ATTEMPTING TO INSTALL
OR OPERATE THE WATER HEATER.

Detailed installation diagrams are in this manual. These

diagrams will serve to provide the installer with a reference
for the materials and method of piping suggested. IT
IS NECESSARY THAT ALL WATER PIPING AND THE
ELECTRICAL WIRING BE INSTALLED AND CONNECTED
AS SHOWN IN THE DIAGRAMS.

Particular attention should be given to the installation of

thermometers at the locations indicated in the diagrams as
these are necessary for checking the operation of the heater.

Be sure to turn off power when working on or near the electrical

system of the heater. Never touch electrical components

with wet hands or when standing in water. When replacing
fuses always use the correct size for the circuit. See page 12
through 14.

The principal components of the heater are identied on page 6.

The model and rating plate on page 7 interprets certain markings
into useful information. Both of these references should be used
to identify the heater, its components and optional equipment.

2. The installation must conform with these instructions and the
local code authority having jurisdiction and the requirements
of the power company. In the absence of code requirements,

follow NFPA-70 (current edition). The National Electrical Code

may be ordered from: National Fire Protection Association, 1
Batterymarch Park, Quincy, MA 02269.

3. If after reading this manual you have any questions or do not
understand any portion of the instructions, call the toll free
number on the back cover for further assistance.

A sample rating plate and barcode tag are shown on page 7 of this

manual. In order to expedite your request, please have the serial
number and item ID from the barcode tag available for the technician.

4. Carefully plan your intended placement of the water heater.
Examine the location to ensure the water heater complies with

the “Locating the New Water Heater” section in this manual.

Installation and service of this water heater requires ability

equivalent to that of a licensed tradesman or qualied agency
(page 2) in the eld involved. Plumbing and electrical work are

required.

5. For installation in California this water heater must be braced or
anchored to avoid falling or moving during an earthquake. See
instructions for correct installation procedures. Instructions may

be obtained from California Ofce of the State Architect, 1102 Q

Street, Suite 5100, Sacramento, CA 95811.

6. Massachusetts Code requires this water heater to be installed in
accordance with Massachusetts 248-CMR 2.00: State Plumbing
Code and 248-CMR 5.00.

4

DIMENSIONS AND CAPACITIES DATA

DSED

Tank Capacity

Gallons Liters A B C D Lbs. Kg.

5 19 3 20 1/2 521 mm 16 1/4 412.75 mm 22 1/2 571.5 mm 5 1/4 133.35 mm 82 37.2

10 38 6 26 1/4 667 mm 18 3/4 476.25 mm 25 635 mm 5 1/4 133.35 mm 106 48.1

20 76 18 27 1/4 692 mm 20 1/2 520.7 mm 26 1/2 673.1 mm 5 3/4 146.05 mm 130 59

30 114 24 35 3/4 908 mm 20 1/2 520.7 mm 26 1/2 673.1 mm 5 3/4 146.05 mm 150 68

40 151 36 45 3/4 1,162 mm 20 1/2 520.7 mm 26 1/2 673.1 mm 5 3/4 146.05 mm 190 86.2

50 189 90 54 3/4 1,391 mm 20 1/2 520.7 mm 26 1/2 673.1 mm 5 3/4 146.05 mm 221 100.2

65 246 90 50 1/2 1,283 mm 26 1/2 673.1 mm 33 1/2 850.9 mm 7 177.8 mm 267 121.1

80 303 90 49 1/4 1,251 mm 28 711.2 mm 35 889 mm 7 177.8 mm 285 129.3

100 379 90 58 1/4 1,480 mm 28 711.2 mm 35 889 mm 7 177.8 mm 354 160.6

120 450 90 63 1/4 1,607 mm 30 762 mm 37 939.8 mm 7 1/2 190.5 mm 420 190.5

Maximum

KW Input

All Dimensions in Inches (mm) Approximate Shipping Wt.

RECOVERY RATE IN GALLONS PER HOUR *

Temperature Rise °F

STANDARD

KW INPUT

3 10,239 41 31 24 20 17 15 13 12 11 10 10 9

6 20,478 82 62 49 41 35 31 27 25 22 21 19 18

9 30,717 123 92 74 62 53 46 41 37 34 31 28 26

12 40,956 164 123 98 82 70 61 55 49 45 41 38 35

15 51,195 205 154 123 102 88 77 68 61 56 51 47 44

18 61,434 246 184 148 123 105 92 82 74 67 62 57 53

24 81,912 328 246 197 164 140 123 109 98 90 82 76 70

30 102,390 410 308 246 205 176 154 137 123 112 103 95 88

36 122,868 492 369 295 246 211 184 164 148 134 123 113 105

45 153,585 615 461 369 307 263 230 205 184 168 154 142 132

54 184,302 738 554 443 359 316 277 246 221 201 185 170 158

60 204,780 819 615 492 410 351 307 273 246 223 205 189 176

75 255,975 1025 768 615 512 439 384 341 307 279 256 236 219

90 307,170 1229 922 738 615 527 461 410 369 335 307 284 263

BTU/

HOUR

30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140°

5

FEATURES AND COMPONENTS

Below is an illustration of the water heater with its features called out. The text of this manual will refer to the items shown.

UIM - USER INTERFACE MODULE

(on front of hinged access door)

FIGURE 1.

6

All models are listed

by Underwriters

Laboratories Inc.

APPROVALS

ASME

MODEL AND RATING

LOCATING THE NEW WATER HEATER

FACTS TO CONSIDER ABOUT THE LOCATION

Carefully choose a location for the new water heater. The placement
is a very important consideration for the safety of the occupants in
the building and for the most economical use of the appliance.

Whether replacing an old water heater or putting the water heater in
a new location, the following critical points must be observed. The
water heater must be located:

1. On a level surface. Shim the channel type skid base as
necessary if levelling is required.

2. Near a oor drain. The heater should be located in an area

where leakage of the tank or connections will not result in

damage to the area adjacent to the heater or to lower oors of

the structure.

3. The discharge opening of the temperature and pressure relief
valve should always be piped to an open drain.

4. Close to the point of major hot water usage and the power
supply.

Hot water piping and branch circuit wiring should be as short as possible.

Insulate hot and cold water piping where heat loss and condensation
may be a problem.

Heater construction permits installation, maintenance, and service
work to be performed through the front control panel.

Suggested clearances from adjacent surfaces are 12 inches on top,
30 inches in front for access to the unit.

The heater may be installed on or against combustible surfaces. The

left side and back may be placed ush against adjacent surfaces.

The temperature of the space in which the water heater is installed
must not go below 32°F or above 122°F.

7

Explosion Hazard

Te mperature-Pressure Relief Valve
must comply with ANSI Z21.22­CSA 4.4 and ASME code.

Properly sized Te mperature-Relief
Valve must be installed in opening
provided.

Can result in overheating and
excessive tank pressure.

Can cause serious injury or death.

INSTALLATION REQUIREMENTS

REQUIRED ABILITY

Installation and service of this water heater requires ability

equivalent to that of a qualied agency (page 2) in the eld involved.

Plumbing and electrical work is required.

GENERAL

The installation must conform with these instructions and the
local code authority having jurisdiction and the requirements of
the power company. In the absence of code requirements, follow

NFPA-70 (current edition). In the absence of local codes, the

installation must comply with the latest editions of the National
Electrical Code, NFPA 70 or the Canadian Electrical Code CSA
C22.1. The National Electrical Code may be ordered from:
National Fire Protection Association, 1 Batterymarch Park,
Quincy, MA 02269. The Canadian Electrical Code is available
from the Canadian Standards Association, 8501 East Pleasant
Valley Road, Cleveland, OH 44131.

Do NOT test electrical system before heater is filled with water,
follow the START UP procedure in the OPERATION section of
this manual.

The principal components of the heater are identied in the Features

and Components illustration in Figure 1.

Before changing the factory setting on the thermostat, read the

“Temperature Regulation” section in this manual.

CONTAMINATED WATER

Toxic chemicals, such as those used for boiler treatment shall
not be introduced into this system.

Products of this sort should not be stored near the heater Also,
air which is brought in contact with the water heater should not
contain any of these chemicals. If necessary, uncontaminated air
should be obtained from remote or outside sources.

TEMPERATURE-PRESSURE RELIEF VALVE

MIXING VALVE USAGE:

Water heaters are intended to produce hot water. Water heated
to a temperature which will satisfy space heating, clothes
washing, dish washing, cleaning and other sanitizing needs
can scald and permanently injure you upon cont act. Some
people are more likely to be permanently injured by hot water
than others. These include the elderly, children, the infirm, or
physically/developmentally disabled. If anyone using hot water in
your home fits into one of these groups or if there is a local code
or state law requiring a maximum water temperature at the hot
water tap, then you must take special precautions. In addition to
using the lowest possible temperature setting that satisfies your
hot water needs, a means such as a MIXING VALVE should
be used at the hot water taps used by these people or at the
water heater.

MIXING VALVES for reducing point of use temperature are
available. Consult a qualified inst alle r or ser vic e age nc y. Follow
all manufacturer’s instr uctions for installation of these valves.

This water heater is provided with a properly rated/sized and certied
combination Temperature-Pressure Relief Valve (T&P valve) by the
manufacturer. The T&P valve is certied by a nationally recognized

testing laboratory that maintains periodic inspection of production of
listed equipment of materials as meeting the requirements for Relief

Valves for Hot Water Supply Systems, ANSI Z21.22 • CSA4.4, and

the code requirements of ASME.

If replaced, the new T&P valve must meet the requirements

of local codes, but not less than a combination Temperature-

Pressure Relief Valve rated/sized and cer tied as indicated in
the above paragraph. The new T&P valve must be marked with

a ma ximum set pressure not to exceed the marked hydrostatic

working pressure of the water heater (150 psi = 1,035 kPa) and

a discharge capacity not less than the water heater Btu/hr or kW
input rate as shown on the water heater’s model rating label.

NOTE: In addition to the factory installed Temperature-Pressure
Relief Valve on the water heater, each remote storage tank that
may b e install ed and pi pe d to a water heating applian ce must a lso
have its own properly sized, rated and approved Temperature­Pressure Relief Valve installed. Call the toll free technical
suppor t phone number listed on the back cover of this manual
for technical assistance in sizing a Temperature-Pressure Relief
Valve for remote storage tanks.

8

For safe operation of the water heater, the Temperature-Pressure

CAUTION

• Temperature-Pressure Relief Valve discharge

pipe must terminate at adequate drain.

Water Damage Hazard

DANGER

• Burn hazard.

• Hot water discharge.

• Keep clear of Temperature

Pressure Relief Valve
discharge outlet.

Relief Valve must not be removed from its designated opening
nor plugged. The Temperature-Pressure Relief Valve must be

installed directly into the tting of the water heater designed for

the Temperature-Pressure Relief Valve. Install discharge piping so

that any discharge will exit only within 6 inches (15.2 cm) above,
or at any distance below the structural oor. Be certain that no

contact is made with any live electrical part. The discharge opening
must not be blocked or reduced in size under any circumstances.

Excessive length, over 30 feet (9.14 m), or use of more than four

elbows can cause restriction and reduce the discharge capacity of
the Temperature-Pressure Relief Valve.

No valve or other obstruction is to be placed between the
Temperature-Pressure Relief Valve and the tank. Do not connect

discharge piping directly to the drain unless a 6” (15.2 cm) air gap is

provided. To prevent bodily injury, hazard to life, or property damage,
the Temperature-Pressure Relief Valve must be allowed to discharge
water in adequate quantities should circumstances demand. If the
discharge pipe is not connected to a drain or other suitable means,

the water ow may cause property damage.

T&P Valve Discharge Pipe Requirements:

Shall not be smaller in size than the outlet pipe size of the •
valve, or have any reducing couplings or other restrictions.

Shall not be plugged or blocked.•
Shall not be exposed to freezing temperatures.•
Shall be of material listed for hot water distribution.•
Shall be installed so as to allow complete drainage of both the •

Temperature-Pressure Relief Valve and the discharge pipe.

Must terminate a maximum of six inches above a oor drain or •

external to the building. In cold climates, it is recommended that
the discharge pipe be terminated at an adequate drain inside
the building.

Shall not have any valve or other obstruction between the relief •
valve and the drain.

ensure that (1) no one is in front of or around the outlet of the
Temperature-Pressure Relief Valve discharge line, and (2) the

water manually discharged will not cause any bodily injury or
property damage because the water may be extremely hot. If after
manually operating the Temperature-Pressure Relief Valve, it fai ls
to completely reset and continues to release water, immediately
close the cold water inlet to the water heater, follow the draining
instructions in this manual, and replace the Temperature­Pressure Relief Valve with a properly rated/sized new one.

Note: The purpose of a Temperature-Pressure Relief Valve is to
prevent excessive temperatures and pressures in the storage tank. The

T&P valve is not intended for the constant relief of thermal expansion.

A properly sized thermal expansion tank must be installed on all closed
systems to control thermal expansion, see Closed Water Systems and
Thermal Expansion on page 9.

If you do not understand these instructions or have any questions
regarding the Temperature-Pressure Relief Valve call the toll
free number listed on the back cover of this manual for technical
assistance.

WATER LINE CONNECTIONS

This manual provides detailed piping installation diagrams (see back
section of this manual) for typical methods of application. For the heater

inlet and outlet connections, di-electric unions are recommended. The
water heater may be installed by itself, or with a separate storage
tank, on both single and two-temperature systems. When used with
a separate storage tank, the circulation may be either by gravity or by
means of a circulating pump. When a circulating pump is used it is

important to note that the ow rate should be slow so that there will be

a minimum of turbulence inside the water heater.

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 ow

preventers. Devices such as these cause the water system to be a
closed system.

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 Temperature-Pressure Relief 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.

Th e Temp e rat ure-Pr essure Reli ef Valve must be man ual ly
operated at least twice a year. Caution should be taken to

A properly sized thermal expansion tank must be installed on all
closed systems to control the harmful effects of thermal expansion.
Co nt act a local plumbing ser vice age ncy t o have a therma l
expansion tank installed.

9

ELECTRICAL DATA

GENERAL

Check the water heater model and rating plate information against
the characteristics of the branch circuit electrical supply. Do not
connect the water heater to an improper source of electricity.

Voltage applied to the water heater should not vary more than +5%
to -10% of the model and rating plate marking for satisfactory operation.

Do NOT energize the branch circuit for any reason before the water

heater tank is lled with water. Doing so may cause the heating

elements to fail.

The installation must conform to these instructions and the local
code authority having jurisdiction. Grounding and electrical wiring
connected to the water heater must also conform to the National
Electrical Code, NFPA 70. This publication is available from The
National Fire Protection Association, 1 Batterymarch Park, Quincy,
MA 02269.

BRANCH CIRCUIT

The branch circuit wire size should be established through reference

to the NEC (National Electrical Code) or other locally approved

sources in conjunction with the water heater amperage rating. Wire
rated at 75°C should be used. For convenience, portions of the wire
size tables from the Code are reproduced in Table 1 on page 11. It
is suggested the electrician size the branch circuit at 125 percent of
the water heater rating and further increase wire size as necessary
to compensate for voltage drop in long runs. Voltage drop should not
exceed 3% at the water heater.

HEATER CIRCUITS

The water heater’s electrical components are pictured and identied

in the Features and Components illustrations in Figure 1 on page 6.
The model and rating plate provides heater circuit ratings. There are
two main electrical circuits:

Control Circuit: Power supply for the electromagnetic
contactor coils. 120V power is s upplied t o t he contac to r coils

by the CCB (Central Control Board) see wiring diagrams in

this manual starting on page 12.

Power Circuit: High voltage, single or three phase, circuit that
carries the heating element load.

The following section and pages describe the water heater circuits
and includes wiring diagrams.

CONTROL CIRCUITS

The water heater is equipped with an electronic control system. The

system includes a CCB (Central Control Board) circuit board, an

immersion temperature probe with ECO for temperature sensing and

limiting, a UIM (User Interface Module) for user interface & information

display and element current sensors for monitoring the power circuits.
Refer to the control circuit label on the water heater for details. The
CCB is powered by a small 120V/24V transformer. The control circuit
operates on 120V supplied by a larger 100VA transformer.

Sequence of Operation

1. When the control is powered, the UIM should display model
information, water temperature, operating setpoint, heating
status and operating mode.

2. If the control determines that the actual water temperature inside
the tank is below the programmed operating setpoint minus the

(1st) differential setpoint, a call for heat is activated.

3. After all safety checks are veried the CCB will energize the
contactor coil(s). On models with more than one heating
element the upper most heating elements are energized rst.

Successive heating elements are energized according to
programmed differential setpoints for each heating element.

4. The control remains in the heating mode until the water
temperature reaches the programmed operating setpoint. At
this point the contactors will be de-energized.

5. The control system now enters the standby operating mode
while continuing to monitor the water temperature and the state
of other system devices. If the water temperature drops below

the programmed Operating Setpoint minus the (1st) differential

setpoint, the control will automatically return to step 2 and repeat
the heating cycle.

POWER CIRCUIT

Power circuit wiring is type THHN (or equivalent) rated 600 volts,

105°C, sized as necessary.

The following wiring diagrams are included in this manual to show
typical arrangements of electrical components in the control and
power circuits by voltage and phase characteristics. They are to be
used as a reference by the installer or servicer in performing their
work. An actual diagram of the water heater wiring is furnished with
the heater.

10

TABLE 1.

Allowable Ampacities of Insulated Conductors

Not More Than Three Conductors in Raceway or Cable or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F)

Size Temperature Rating of Conductor Size

AWG

MCM

18
16
14
12
10

8
6
4
3
2
1
0

00

000

0000

250
300
350
400
500

Ambient

Temperature

°C
31-40
41-50
51-60
61-70
71-80

= The load current rating and the overcurrent protection for these conductors shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10

AWG copper; or 15 amperes for 12 AWG and 25 amperes for 10 AWG aluminum and copper-clad aluminum.

60°C

(140°F)

TYPES
RUW, T
TW, UF

COPPER ALUMINUM OR COPPER-CLAD ALUMINUM

......

......

15
20
30
40
55
70
80

For ambient temperatures over 30°C, multiply the ampacities shown by the appropriate correction factor to determine the maximum
allowable load current.

.82

.58

......

......

......

75°C

(167°F)

TYPES

FEPW

RH, RHW

RUH,
THW,

THWN,

XHHW

USE, ZW

......

......

15
20
30
45
65

85
100
115
130
150
175
200
230
255
285
310
335
380

.88
.75
.58
.35

......

85°C

(185°F)

TYPES

V, MI

......

22
25
30
40
50
70

90
105
120
140
155
185
210
235
270
300
325
360
405

.90
.80
.67
.52
.30

90°C

(194°F)

TYPES
TA, TBS
SA, AVB

SIS, =FEP,

=FEPB,

=RHH,

=THHN,

=XHHW*

21
22
25
30
40
50
70

90
105
120
140
155
185
210
235
270
300
325
360
405

CORRECTION FACTORS

.91
.82
.71
.58
.41

60°C

(140°F)

TYPES
RUW, T
TW, UF

......

......

......

15
25
30
40
55
65
75

.82

.58

......

......

......

75°C

(167°F)

TYPES

RH, RHW

RUH

THW,

THWN

XHHW,

USE

......

......

......

15
25
40
50
65
75

90
100
120
135
155
180
205
230
250
270
310

.88
.75
.58
.35

......

85°C

(185°F)

TYPES

V, MI

......

......

......

25
30
40
55
70
80

95
110
125
145
165
185
215
240
260
290
330

.90
.80
.67
.52
.30

90°C

(194°F)

TYPES

TA, TBS,

SA, AVB

SIS,

=RHH,

=THHN,

=XHHW*

......

......

......

25
30
40
55
70
80

95
110
125
145
165
185
215
240
260
290
330

.91
.82
.71
.58
.41

AWG

MCM

......

......

......

12
10

8
6
4
3
2
1
0

00

000

0000

250
300
350
400
500

Ambient

Temperature

°F

86 –104
105–122
123–141
142–158
159–176

3
6

9
12
15

24
30

45
54

Immersion

Heaters***

No. Of

Wattage

1 3,000
1 6,000
1 9,000
1 12,000
1 15,000

1 18,000
2 12,000
2 15,000

2 18,000
3 15,000
3 18,000

Standard

KW

Ratings

18*

36*

60** 4 15,000 4 4
75** 5 18,000
90** 5 18,000

* 208V models use one additional immersion heater.
** Available on 50 gallon models or larger.
*** Each immersion heater contains three electric elements.

Number of 50A Contractors

208V 240V 480V 208V 240V 277V 480V 208V 240V 480V

1

1

2

2

3 3

5 5 3

STANDARD KW INPUTS

14.4

28.8

1

2

43.3

57.7

72.1

86.5

115.4

144.2

173.1

216.3
N/A
N/A
N/A
N/A

TABLE 2.

Single Phase Three Phase

12.5

25.0

37.5

50.0

62.5

75.0

100.0

125.0

150.0

187.5

225.0

250.0
N/A
N/A

Full Load Current In Amperes

10.8

21.2

32.5

43.3

54.2

65.0

86.6

108.3

130.0

162.5

194.9

216.6
N/A
N/A

6.3

12.5

18.8

25.0

31.3

37.5

50.0

62.5

75.0

93.8

112.5
125
156
188

11

8.3

16.7

25.0

33.3

41.6

50.0

66.6

83.3

99.9

124.9

149.9

166.7

208.4
250

7.2

14.4

21.7

28.9

36.1

43.3

57.7

72.2

86.6

108.3

129.9
145
181
217

3.6

7.2

10.8

14.4

18.0

21.7

28.9

36.1

43.3

54.1

65.0
72
90

108