American Water Heater HeavyDuty Surface Thermostat Commercial Electric STCE3150 80 119 User Manual

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by  the  manufacturer.  The  valve  is  certified  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 • CSA 4.4, and the code requirements of ASME.
If replaced, the new valve must meet the requirements of local 
c o d e s ,  b u t  n o t  l e s s  t h a n  a  c o m b i n a t i o n  t e m p e r a t u r e  a n d  p r e s s u r e  
relief valve rated/sized and certified as indicated in the above 
paragraph. The new valve must be marked with a maximum set 
p r e s s u r e  n o t  t o  e x c e e d  t h e  m a r k e d  h y d r o s t a t i c  w o r k i n g  p r e s s u r 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  be  installed  directly  into  the  fitting  of  the  water  heater 
designed  for  the  relief  valve.  Install  discharge  piping  so  that 
any discharge will exit only within 6 inches (15.2 cm) above, or 
external to the structure. Do not pipe the discharge to a crawl 
s p a c e .  B e  c e r t a i n  t h a t  n o  c o n t a c t  i s  m a d e  w i t h  a n y  l i v e  e l e c t r i c a l 
par t . T he disc harge opening must not be blo c ked o r reduc ed 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 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 bodily injury, 
hazard to life, or property damage, the 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 flow may cause property damage.
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 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 floor 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.
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 
property  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. 
I f  y o u  d o  n o t  u n d e r s t a n d  t h e s e  i n s t r u c t i o n s  o r  h a v e  a n y  q u e s t i o n s  
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,  dielectric  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  flow  rate  should  be 
slow so that there will be a minimum of turbulence inside the 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 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 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  must  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. 
						

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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.
Allowable Ampacities of Insulated ConductorsNot 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.
Table 3.  
						

							13
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 identified 
in Figure 2 and Figure 3 The model and rating plate illustration on 
page 4 identifies 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 6
•  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 configuration, refer to the “WYE Configuration 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),  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 verified, 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 2)   
  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 Table 4. 
Table 5. 
Figure 4  Figure 5 
KW
Input Number Of 
Elements Element 
wattage Full Load Current In Amperes
Number Of 
Thermostats Number Of
Fuses
Single Phase Three Phase
208V 240V 277V480V208V240V480V
6
32000
2925 22131715 8
3 6
9
30004438 3319252211
12 40005850 4425342915
13.5 45006557 4929383317
15 50007363 5532423718
18 6000- - - 75 6538- - -  4422
18
63000
87- - -  - - - - - -  50- - -  - - - 
6 12
24
400011 6100 8750675829
27 450013011 3 9857756533
30 5000145125 10963847337
36 6000- - - 150 13075- - -  8744
36
94000
173- - -  - - - - - - 100 - - - - - - 
9 18
40.5
4500195169 1478511 3 9849
45 5000217188 16394125 109 55
54 6000- - - 225 19511 3150 130 65 
						

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CCB (CENTRAL CONTROL BOARD)
CONTROL CIRCUIT DIAGRAM - ELECTRONIC CONTROL MODELS
Figure 6
WIRING DIAGRAMS 
						

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DIAGRAM 1.
WIRING DIAGRAMS
POWER CIRCUIT DIAGRAMS - ELECTRONIC CONTROL MODELS
The water heater’s electrical components are pictured and identified on page 7. The following describes the heater circuits and includes wiring 
diagrams. All heater circuits are designed for 60/50 hertz alternating current. The water heater circuit wiring is 12 AWG, AWM, or TEW type, 
rated 600 volts, 105°C. Fusing consists of three 30 amp fuses for each contactor. Fusing is an optional feature for Canadian models.
THREE ELEMENTS - SINGLE AND THREE PHASE
SIX ELEMENTS - SINGLE AND THREE PHASE 
						

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WIRING DIAGRAMS
NINE ELEMENT - SINGLE AND THREE PHASE
CONVERSION TO SINGLE PHASE
When the heater is shipped for connection to a three-phase electrical 
service, it may be connected to a single-phase electrical service of 
the same voltage by:
1. Disconnect blue wires and yellow wires from terminal L3.
2. Reconnect all blue wires to terminal L1 (with black wires).
3. Reconnect all yellow wires to terminal L2 (with red wires).
4. Connect incoming power to terminals L1 and L2.
CONVERSION TO THREE PHASE
When heater is shipped for connection to a single-phase electrical 
service,  it  may  be  connected  to  a  three-phase  electrical  service  of 
the same voltage by:
1. Disconnect blue wires from terminal L1.
2. Disconnect yellow wires from terminal L2.
3. Reconnect all blue wires and yellow wires to terminal L3.
4. Connect incoming power to terminals L1, L2, and L3.
DIAGRAM 2. 
						

							17
WIRING DIAGRAMS
POWER CIRCUIT DIAGRAMS - SURFACE MOUNT CONTROL MODELS
The water heater’s electrical components are pictured and identified on page 8. The following describes the heater circuits and includes 
wiring  diagrams. All  heater  circuits  are  designed  for  60/50  hertz  alternating  current.  The  water  heater  circuit  wiring  is  12 AWG, AWM,  or 
TEW type, rated 600 volts, 105°C. Fusing consists of two 30 amp fuses for each element. Fusing is an optional feature for Canadian models.DIAGRAM 3. 
						

							18
WIRING DIAGRAMS
CONVERSION TO SINGLE PHASE
When the heater is shipped for connection to a three-phase electrical 
service, it may be connected to a single-phase electrical service of 
the same voltage by:
1. Disconnect blue wires from terminal L2.
2. Connect all blue wires to terminal L1 (with black wires).
3. Disconnect all red wires from terminal L3.
4. Connect all red wires to terminal L2 (with yellow wires).
5. Connect incoming power to terminals L1 and L2.
CONVERSION TO THREE PHASE
When heater is shipped for connection to a single-phase electrical 
service, it may be connected to a three-phase electrical service of 
the same voltage by:
1. Disconnect blue wires from terminal L1
2. Disconnect red wires from terminal L2.
3. Connect all blue wires to terminal L2 (with yellow wires).
4. Connect red wires to terminal L3.
5. Connect incoming power to terminals L1, L2 and L3.
NINE ELEMENTS - SINGLE AND THREE PHASE
DIAGRAM 4. 
						

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OPERATION
GENERAL
Refer  to  the  Features  and  Components  section  of  this  manual 
(pages  7  &  8)  for  the  location  of  components  mentioned  in  the 
instructions that follow.
NEVER turn on power to the water heater without being certain the 
water heater is filled with water and a temperature and pressure 
relief valve is installed in the relief valve opening.
DO NOT TEST ELECTRICAL SYSTEM BEFORE HEATER IS 
FILLED WITH WATER. FOLLOW FILLING AND START-UP 
INSTRUCTIONS IN OPERATION SECTION.
FILLING THE WATER HEATER
1. Turn off the electrical disconnect switch.
2.  Close the water heater drain valve.
3.  Open a nearby hot water faucet to permit the air in the system to 
escape.
4.  Fully open the cold water inlet pipe valve allowing the heater and 
piping to be filled.
5.  Close the hot water faucet as water starts to flow. The heater is 
now ready for STARTUP and TEMPERATURE REGULATION.
INITIAL START UP
The following checks should be made by the installer when the heater 
is placed into operation for the first time.
1. Turn off the electrical disconnect switch.
2.  Open the front panel, check all water and electrical connections for 
tightness. Also check connections on top and side of heater. Repair 
water leaks and tighten electrical connections as necessary.
3. Depress the red manual reset button on each Thermostat/ECO 
combination control (Surface Mount Control Models only).
4.  Turn on the electrical disconnect switch.
5.  Observe  the  operation  of  the  electrical  components  during 
the  first  heating  cycle.  Use  care  as  the  electrical  circuits  are 
energized.
6.  Close the front panel.
Temperature control and contactor operation should be checked by 
allowing heater to come up to temperature and shut off automatically. 
Use care as the electrical circuits are energized.
DRAINING THE WATER HEATER
It  is  recommended  that  the  water  heater  storage  tank  be  drained 
and  flushed  every  6  months  to  reduce  sediment  buildup.  The 
water  heater  should  be  drained  if  being  shut  down  during  freezing 
temperatures. See Features And Components in this manual for the 
location of the water heater components described below.
Burn harzard.
Hot water discharge.
Keep  hands   clear  of  drain
valve  discharge.
TO	DRAIN	THE	WATER	HEATER	STORAGE	TANK:
1.  Turn off the electrical supply to the water heater at the breaker 
or disconnect switch.
2.  Ensure the cold water inlet valve is open.
3.  Open  a  nearby  hot  water  faucet  and  let  the  water  run  until  the 
water is no longer hot.
4.  Close the cold water inlet valve to the water heater.
5.  Connect a hose to the water heater drain valve and terminate it 
to an adequate drain.
6.  Open  the  water  heater  drain  valve  and  allow  all  the  water  to 
drain from the storage tank.
7.  Close the water heater drain valve when all water in the storage 
tank has drained.
8.  Close the hot water faucet opened in Step 3.
9.  If  the  water  heater  is  going  to  be  shut  down  for  an  extended 
period, the drain valve should be left open. 
						

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HIGH TEMPERATURE LIMIT CONTROLS (ECO)
Both  the  ELECTRONIC  CONTROL  and  SURFACE  MOUNT 
CONTROL model water heaters are equipped with one or more ECO 
(energy cut off) non adjustable high temperature limit control(s). An 
ECO  is  a  normally  closed  switch  that  opens  (activates)  on  a  rise 
in  temperature.  If  the  ECO  switch  contacts  open  (activate)  due  to 
abnormally high water temperatures it will lock-out and disable further 
heating  element  operation.  It  is  important  that  a  qualified  service 
agent be contacted to determine the reason for the ECO activation 
before  resetting  the  ECO.  Once  the  reason  has  been  determined 
and corrected the ECO(s) can be reset as follows:
Surface Mount Control ModelsSurface  Mount  Control  models  have  multiple  surface  mounted 
Thermostat/ECO combination controls. One for each installed heating 
element - see the Surface Mount Control wiring diagrams in this manual. 
The  ECO  high  temperature  limit  switch  contacts  on  each  control  will 
open when the tank temperature reaches approximately 200°F/93°C. If 
activated, the ECO reset button will be slightly extended and stiff to the 
touch. When the ECO switch contacts open (activate) voltage to ONE 
heating element ONLY is terminated to prevent further heating operation 
of that element. Voltage may still be present at other heating elements 
and they may still be heating the water.
The ECO is a manual reset switch. Should one or more ECO activate, 
the tank temperature must drop below 120°F/49°C before an ECO 
can be reset. To manually reset an ECO:
1. Disconnect the power supply to the water heater.
2.  Allow the tank temperature to cool below 120°F/49°C.
3.  Remove the front control cover from the effected control(s).
4.  Press the manual reset button on each of the effected controls.
5.  Once the control(s) has been reset the control cover should be 
replaced prior to restoring power to the water heater.
Electronic Control ModelsThe ECO high temperature limit switch is located inside the immersion 
Temperature  Probe  (two  red  wires)  on  ELECTRONIC  CONTROL 
models.  The  ECO  switch  contacts  will  open  when  the  water 
temperature  reaches  approximately  202°F/94°C.  When  the  ECO 
switch  contacts  open  (activate)  the  electronic  control  system  locks 
out and displays a Fault message. Voltage to the contactor coils and 
heating elements is terminated to prevent further heating operation. 
Should  the  ECO  activate,  the  water  temperature  must  drop  below 
140°F/60°C before the control system can be reset. Once the water 
temperature has cooled below this point the power supply to the water 
heater must be turned off and on again to reset the control system.
THERMOSTAT CONTROLS
The water heaters covered in this instruction manual are equipped with 
adjustable thermostat controls to control water temperature. Hot water 
temperatures required for automatic dishwasher and laundry use can 
cause  scald  burns  resulting  in  serious  personal  injury  and/or  death. 
The temperature at which injury occurs varies with the persons age and 
duration of exposure. The slower response time of children, the elderly 
or disabled persons increases the hazards to them. Never allow small 
children  to  use  a  hot  water  tap  or  draw  their  own  bath  water.  Never 
leave a child or disabled person unattended in a bathtub or shower.
The  water  heater  should  be  located  in  an  area  where  the  general 
public does not have access to set temperatures.
Setting water heater temperatures at 120°F (49°C) will reduce  risk of 
scalds. Some areas require settings at specific lower temperatures.
THERMOSTAT SETTINGS - SURFACE MOUNT CONTROL 
Adjustment of temperature controls on surface mounted controls is 
to be performed by a qualified service agent at initial start-up.
These models have multiple thermostat/ECO combination controls 
one  for  each  heating  element  installed. These  thermostats  are  set 
from the factory at 140°F/60°C. Set the thermostat dial at the lowest 
setting  which  produces  an  acceptable  hot  water  supply.  This  will 
always give the most energy efficient operation.
The water heater is supplied with thermostats that may come from 
different  manufactures  and  have  different  temperature  indications 
as described below.
Thermodisc ThermostatsThermodisc  thermostats  are  adjustable  from  approximately  120°F 
(49°C) (lowest setting) to 181°F (83°C) (highest setting) see figure 
7A. These thermostats are set from the factory at approximately the 
140°F (60°C) setting. The over temperature device (ECO high limit) 
attached to each thermostat has a manual reset.
APCOM Thermostats
Apcom thermostats have three designated set points; LO, MED and 
HI. See figure 7B. The approximate equivalent temperatures for these 
three settings are: LO = 140°F (60°C), MED = 160°F (71°C) and HI 
=  181°F  (83°C). These  thermostats  are  set  from  the  factory  at  the 
MED 140°F (60°C) setting.  The over temperature device (ECO high 
limit) attached to each thermostat has a manual reset.
 
APCOM   IN C
40A 120-277 VA C
25A.480 VA C  125VA.PT.DTY.   120-480 VAC
MEDLO
HIMODELWH19HC
        30A 120-250 VAC             22A 277 VA C        12.5A 480VAC125 VA.PT.DTY. 120-480 VA C
Figure 7A  Figure 7B
Figure 7 shows the approximate time-to-burn relationship for normal 
adult skin.
Water 
Temperature °F Time for 1st Degree 
Burn  
(Less Severe Burns) Time for Permanent 
Burns 2nd & 3rd  Degree  
(Most Severe Burns)
11 0 (normal shower temp.)
11 6 (pain threshold)
11 6 35 minutes 45 minutes
122 1 minute 5 minutes
131 5 seconds 25 seconds
140 2 seconds 5 seconds
149 1 second 2 seconds
154 instantaneous 1 second
(U.S. Government Memorandum, C.P.S.C., Peter L. Arm- strong, Sept. 15,1978)
Table 6.
TEMPERATURE REGULATION