A.O. Smith Dve-52, Dve-80, Dve-120 User Manual
Instruction Manual
COMMERCIAL ELECTRIC WATER HEATERS
MODELS DRE-52/80/120 SERIES 100
& DVE-52/80/120 SERIES 100
INSTALLATION - OPERATION - SERVICE
- MAINTENANCE - LIMITED WARRANTY
500 Tennessee Waltz Parkway
Ashland City, TN 37015
ASME
(OPTIONAL)
Thank you for buying this energy efcient water heater.
We appreciate your condence in our products.
PLACE THESE INSTRUCTIONS ADJACENT TO HEATER AND NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE.
PRINTED IN THE U.S.A 0908 196674-002
1
SAFE INSTALLATION, USE, AND SERVICE
The proper installation, use and servicing of this water heater is extremely important to your safety and the safety of others.
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, could 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, may result
in minor or moderate injury.
CAUTION used without the safety alert
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, including formaldehyde.
symbol indicates a potentially hazardous
situation which, if not avoided, could result
in property damage.
IMPORTANT DEFINITIONS
• QualiedInstallerorServiceAgency:
Installation and service of this water heater requires ability equivalent to that of a Qualied Agency (as dened by ANSI below) in the
eld involved. Installation skills such as plumbing, electrical supply are required in addition to electrical testing skills when performing
service.
• ANSIZ223.12006Sec.3.3.83:
“Qualied 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.”
2
GENERAL SAFETY INFORMATION
PRECAUTIONS
DO NOT USE THIS APPLIANCE IF ANY PART HAS BEEN UNDER
WATER. Immediately call a qualied 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 qualied 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
heater that has not been used for a long period of time (generally two
weeks or more). Hydrogen gas is extremely ammable.
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 is present
there will probably be an unusual sound such as air escaping through the pipe
as the water begins to ow.
OPEN FLAME NEAR THE FAUCET AT THE TIME IT IS OPEN.
THERE SHOULD BE NO SMOKING OR
To reduce the
3
TABLE OF CONTENTS
SAFE INSTALLATION, USE AND SERVICE..................................... 2
GENERAL SAFETY INFORMATION .................................................3
TABLE OF CONTENTS ..................................................................... 4
INTRODUCTION ...............................................................................4
Preparing for the New Installation .............................................4
DIMENSIONS AND CAPACITIES DATA ...........................................5
APPROVALS ..................................................................................... 6
FEATURES AND COMPONENTS .................................................7-8
LOCATING THE NEW WATER HEATER .......................................... 9
INSTALLATION ...............................................................................10
Required Ability ........................................................................10
General .................................................................................... 10
Mixing Valve Usage ................................................................. 10
Chemical Vapor Corrosion .......................................................10
Circulating Pump .....................................................................10
Insulation Blankets ..................................................................10
Temperature-Pressure Relief Valve .................................... 10-11
Water Line Connection ............................................................ 11
Closed Water System .............................................................. 11
Thermal Expansion .................................................................. 11
ELECTRICAL ..................................................................................12
OPERATION .................................................................................... 19
General .................................................................................... 19
Filling the Water Heater ........................................................... 19
Start Up ...................................................................................19
Draining the Water Heater ....................................................... 19
TEMPERATURE REGULATION .....................................................20
High Temperature Devices ......................................................20
Thermostat Controls ................................................................ 20
Thermostat Settings – Surface Mount Control Models ............ 20
Thermostat Settings – Electronic Control Models ................... 21
ELECTRONIC CONTROL MODELS OPERATION ......................... 21
Control System Features ......................................................... 21
Control System Navigation ...................................................... 21
Desktop Screen ..................................................................21-23
Temperatures Menu ............................................................23-24
Temperature Settings ..............................................................24
Heater Status Menu ................................................................. 25
Economy Mode Setup Menu ..............................................25-26
Economy Mode Settings .....................................................26-28
Alarm Output Setup Menu .......................................................29
Display Settings Menu ............................................................. 29
Heater Information Menu .................................................... 29-30
Current Fault / Alert Menu .......................................................30
Fault Occurrence Menu ........................................................... 30
Restore Factory Defaults Menu .......................................... 30-31
MAINTENANCE ..............................................................................31
General ............................................................................... 31-32
Flushing ...................................................................................32
Sediment Removal ..................................................................32
Water and Lime Scale Removal .............................................. 32
TROUBLESHOOTING CHECKLIST ............................................... 33
Not Enough or No Water .........................................................33
Water Heater Makes Strange Sounds ..................................... 33
If You Cannot Identify or Correct the Source of Malfunction
Leakage Checkpoints ..............................................................34
PIPING DIAGRAMS ...................................................................35-42
WARRANTY ....................................................................................43
............17
INTRODUCTION
Thank You for purchasing this water heater. Properly installed and
maintained, it should give you years of trouble free service.
Abbreviations Found In This Instruction Manual:
• 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
PREPARING FOR THE INSTALLATION
1. Read the “General Safety Information” 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 13.
The principal components of the heater are identied on pages 7 & 8.
The model and rating plate on page 6 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). 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.
3. If after reading this manual you have any questions or do not
understand any portion of the instructions, call the toll free number
listed on the back cover of this manual for technical assistance.
A sample rating plate is shown on page 6 of this manual. In order
to expedite your request, please have full model and serial number
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 qualied 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 Ofce 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
DRE/DVE MODEL DIFFERENCES
This Instruction Manual covers two models of
commercial electric water heaters; DRE models and
DVE models. These two models are equipped from the
factory with different controls.
DRE models are factory equipped with surface mounted
thermostat/ECO combination controls. DVE models are
factory equipped with an electronic control system.
In this Instruction Manual “DRE” models are referred to
as: “Surface Mount Control” models.
In this Instruction Manual “DVE” models are referred to
as: “Electronic Control” models.
Model Number Tank Capacity in Gallons (Liters) A - Inches (mm) B - Inches (mm) C - Inches (mm) Inlet/Outlet
DRE/DVE-52 50 (189.3) 55 3/4 (1416) 21 3/4 (552) 27 (685) 1 1/4
DRE/DVE-80 80 (302.8) 60 1/4 (1350) 25 1/2 (648) 31 (787) 1 1/4
DRE/DVE-120 119 (450.5) 62 1/4 (1581) 29 1/2 (749) 35 (889) 1 1/4
RECOVERY RATE IN GALLONS PER HOUR*
Temperature Rise °F
Standard
KW Input
BTU/
Hour 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140°
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
13.5 46,075 184 138 111 92 79 69 62 55 50 46 43 40
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 61 57 53
24 81,912 328 246 197 164 140 123 109 98 89 82 76 70
27 92,151 369 276 221 184 158 138 123 111 101 92 85 79
30 102,390 410 307 246 205 176 154 137 123 112 102 95 88
36 122,868 492 369 295 246 211 184 164 148 134 123 113 105
40.5 138,226 554 418 3332 277 237 208 1185 166 151 138 128 119
45 153,585 615 461 369 307 263 230 205 184 168 154 142 132
54 184,302 738 553 443 369 316 277 246 221 201 184 170 158
*Figured at 1 KW (3413 Btu) = 4.1 gallons at 100°F temperature rise.
To determine recovery rate per minute, divide recovery rate per hour by 60.
5
APPROVALS
All models meet
National Sanitation
Foundation NSF-5
requirements.
All models are listed
by Underwriters
Laboratories Inc.
MODEL AND RATING
6
FEATURES AND COMPONENTS
ELECTRONIC CONTROL MODELS
FIGURE 1
7
FEATURES AND COMPONENTS
SURFACE MOUNT CONTROL MODELS
FIGURE 2
8
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. 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 construc ti on p er mits i nstallation , maint enance, 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.
9
INSTALLATION
REQUIRED ABILITY
Installation and service of this water heater requires ability equivalent
to that of a qualied 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 NFPA70 (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 lled with water, follow
the START UP procedure in the OPERATION section of this manual.
The principal components of the heater are identified in the
Features and Components illustrations on pages 6 and 7.
CONTAMINATED WATER
Th is water he at er shal l no t be connec ted to any heat ing
system(s) or c om ponent(s) u se d with a n on- potable water
heating appliance.
Toxic chemicals, such as those used for boiler treatment shall not
be introduced into this system.
CIRCULATING PUMP
Field installed circulating pumps should be of all bronze
construction.
INSULATION BLANKETS
Insulation blankets are available t o the gen er al public for
external use on electric water heaters but are not necessary with
this product. The purpose of an insulation blanket is to reduce
the standby heat loss encountered with storage tank heaters.
Your water heater meets or exceeds the EPACT and ASHRAE/
IES 90.1 standards with respect to insulation and standby loss
requirements, making an insulation blanket unnecessary.
Should you choose to apply an insulation blanket to this heater,
you should follow these instructions below. Failure to follow
these instructions can result in f ire, serious personal injury,
or death.
MIXINGVALVEUSAGE:
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 contact. 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 ts 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 satises 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 qualied installer or service agency. Follow all
manufacturer’s Instructions for installation of these valves. Before
changing the factory setting on the thermostat, read the “Temperature
Regulation” section in this manual.
• Do not cover the temperature and pressure relief (T & P) valve
with an insulation blanket.
• Do not cover the instruction manual. Keep it on the side of the
water heater or nearby for future reference.
• Do obtain new warning and instruction labels for placement on
the blanket directly over the existing labels.
TEMPERATURE-PRESSURE RELIEF VALVE
This water heater is provided with a properly rated/sized and
certified combination temperature - pressure relief valve by the
10
manufacturer. The valve is cer tified 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 Z 21.22 •
CSA 4.4, and the code requirements of ASME.
If replaced, the new valve must meet the requirements of local
cod es, b ut n ot l ess tha n a c ombin ati on t empe rat ure and p res sure
relief valve rated/sized and certified as indicated in the above
paragraph. The new valve must be marked with a maximum set
pre ssu re n ot t o excee d th e ma r ke d hy dro sta t ic work ing p res sur e
of the water heater (150 psi = 1,035 kPa) and a discharge
capacity not less than the water heater Btu/hr or K W input rate
as shown on the water heater’s model rating plate.
For safe operation of the water heater, the temperature and
pressure relief valve must not be removed from its designated
opening nor plugged. The temperature- pressure relief valve
must b e installed directly into the fitting of the water heater
de sign ed f or t he r e lie f valve. I nst a ll disc har g e p ipin g so tha t any
di scha rge w ill ex it o nly w ith in 6 inc hes (15. 2 cm) ab ove, o r at any
distance below the structural floor. 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 elb ows can cause restriction and reduce the discharge
capacity of the valve.
No valve or other obstruction is to be placed between the 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
bo dily i nj ury, haz ard to li fe, or pr op erty damag e, the reli ef valve
must be allowed to discharge water in adequate quantities should
circumstances demand. If the discharge pipe is not c onnected
to a drain or other suitable means, the water flow may cause
property damage.
The temperature-pressure relief valve must be manually
operated at least once a year. Caution should be taken to
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
proper ty damage because the water may be extremely hot. If
after manually operating the valve, it fails 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 temperature-pressure relief valve with
a properly rated/sized new one.
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 heater.
The Discharge Pipe:
• 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 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.
• Shall terminate at an adequate drain.
• Shall not have any valve or other obstruction between the relief
valve and the drain.
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.
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 temperaturepressure 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. Contact a local plumbing service agency to have a
thermal expansion tank installed.
11
ELECTRICAL
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 local codes, the installation must comply with the current editions of the National Electrical Code, NFPA 70 or
the Canadian Electrical Code CSA C22.1.
An electrical ground is required to reduce risk of electrical shock or possible electrocution. The water heater should be connected to a
separate grounded branch circuit with over-current protection and disconnect switch. The water heater should be grounded in accordance
with national and local codes.
Voltage applied to the heater should not vary more than +5% to -10% of the model and rating plate marking for satisfactory operation.
TABLE 310-16. Allowable Ampacities of Insulated Conductors
Not more than three conductors in raceway, cable, or earth (directly buried), based
on ambient temperature of 30°C (86°F)
+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.
*For dry locations only. See 75°C column for wet locations.
12
AMPERAGE TABLE/OVERCURRENT PROTECTION
The tables above provides the total connected heating element load
in amperes for branch circuit conductor and overcurrent protection
sizing. Single-phase heaters are two wire circuits. Three-phase
heaters are three wire circuits. In addition to the foregoing, a
grounded conductor is required.
The rating of the overcurrent protection must be computed on the basis
of 125% of the total connected load amperage. Where the standard
ratings and settings do not correspond with this computation, the next
higher standard rating or setting should be selected.
HEATER CIRCUITS - ELECTRONIC CONTROL MODELS
The water heater’s electrical components are pictured and identied
in Figures 1 and 2. The model and rating plate illustration on page 4
identies heater circuit ratings. The ELECTRONIC CONTROL model
has two electrical circuits.
• The control circuit, which controls the electrical power to heating
elements, referring the following control circuit diagram Figure 3.
• The power circuit, which is operated by the control circuit carries
the electrical load of the heating elements. The following
describes the heater circuits and includes wiring diagrams for
Delta conguration, refer to the “WYE Conguration Insert” for
water heaters operating at 380V/400V/416V/575V. All heater
circuits are designed for 50/60 cycle alternating current.
CONTROL CIRCUIT - ELECTRONIC CONTROL MODELS
These models are 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. Standard equipment
includes control circuit fusing using two, 3 amp, class G fuses with 600
volt rating. Do not substitute fuses of a different rating.
Sequence of Operation
1. When the control is powered, the UIM should display model
information, water temperature, Operating Set Point, 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, a call for heat is activated.
3. After all safety checks are veried, the CCB will energize contactor
coils starting with the lower bank of heating elements (each
diagonal row of three heating elements is considered a “bank” - see
Figure 1) then energize the middle bank (if so equipped) and top bank
(if so equipped). The middle and top banks (if so equipped) are
energized according to programmed 2nd and 3rd differential
set points.
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 in the reverse order.
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, the control
will automatically return to step 2 and repeat the heating cycle.
NOTE: See the Electronic Control Models Operation section for more
detailed information on temperature settings mentioned above.
120 VAC CONTROL CIRCUIT TRANSFORMER CONNECTIONS - ELECTRONIC CONTROL MODELS
13
WIRING DIAGRAMS
CCB (CENTRAL CONTROL BOARD) CIRCUIT BOARD
CONTROL CIRCUIT DIAGRAM - ELECTRONIC CONTROL MODELS
FIGURE 3.
14
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