Bock Water heaters Energy Saver 50A SF Series User manual

Energy Saver
Commercial Electric Energy Saver
Water Heater
IMMERSION AND SURFACE MOUNTED
THERMOSTAT MODELS
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualied service providers)
For Models
50(A)*(SF, CF)-**
80(A)*(SF, CF)-**
120(A)*(SF, CF)-**
*Denotes kW Rating
**Denotes Wiring Code
Manual 238-47174-00B - Save this manual for future reference
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Commercial Electric
Water Heaters
Table of Contents
Page Service Procedure
Introduction/Tools 2 - - -
General Information 3 - - -
Sequence of Operation 10 - - -
Troubleshooting 13 - - -
Heating Element Testing 15 I
Line Voltage Testing 16 II
Fuse Testing 17 III
High Limit (ECO) Testing (Surface Mounted) 18 IV
High Limit (ECO) Testing (Surface Mounted @ 600V) 19 V
High Limit (ECO) Testing (Contactor Models) 20 VI
Thermostat Operation Testing (Surface Mounted) 21 VII
Thermostat Operation Testing (Surface Mounted @ 600V) 22 VIII
Thermostat Operation Testing (Contactor Models) 23 IX
Contactor Operation Testing 24 X
Thermostat Removal & Replacement (Surface Mounted) 26 XI
Thermostat Removal & Replacement (Contactor Models) 27 XII
ECO Removal & Replacement (Contactor Models) 28 XIII
ECO Removal & Replacement (Surface Mounted @ 600V) 29 XIV
Heating Element Removal & Replacement 30 XV
Anode Inspection & Replacement 31 XVI
Generic Parts List 32 - - -
Glossary of Terms 33 - - -
Introduction
This service manual is designed to aid service and maintenance professionals in the function, proper
diagnosis and repair of Bock Water Heaters Commercial Electric Water Heaters.
The text and illustrations in this manual provide step-by-step instructions to facilitate proper operation and
troubleshooting procedures. Contact Bock Water Heaters Technical Support immediately if diagnosis
cannot be made using the methods described in this service manual.
Tools
- Multi-Meter - Philips Head Screw Driver
- 1-1/2” Deep Well Socket - Common Screw Driver
- 1-1/16” Deep Well Socket - Thermometer
- 1/4” Nut Driver - Drain Hose.
Other hand tools: pipe wrench, channel locks, pliers (common & needle nose), wire cutters, wire strippers,
allen wrench set, flash light.
2

3
Commercial Electric
General Information
Bock Waters Heaters Commercial Electric water heaters can be manufacturered
with a choice between two different types of thermostat control options as follows:
Surface Mounted Thermostats.
Immersion Thermostat (contactor models).
The model number is coded to identify the specific thermostat control system used
for a particular unit. Below is a typical model number and coded definitions.
50 SF 6 208/240
Volts
kW Rating
CF - Contactor w/Fuse (Immersion Thermostat)
SF - Surface Thermostat w/Fuse
Tank Capacity
MFG FOR: BOCK WATER HEATERS, INC.
110 S. DICKINSON, MADISON WI 53703
Model No: 50SF-6, 208/240
Serial No: ZB2564812
Cap. 50(gal.)/189.3(liters)
Press: Test 300(psi), Working 150(psi)
Volts 240 Max Temp 180°
Phase Three Amps 29
kW Each 4 Total kW 12 3 Elements
Wattage rating based upon 60 Hz
Model Number
Electrical Characteristics
Typical Rating Plate
Located on Front of Water Heater

4
Contactor Models
General Controls Layout
Ground Lug
Terminal Block
Fuse Block (s)
Contactor (s)
High Limit (ECO)
Direct Immersion Bulb
High Limit (ECO) Control
Immersion Thermostat
Control
Heating Elements
Upper Control Box
Thermostat
Direct Immersion Bulb
Lower Control Box
Lower Control Box
Upper Control Box
Ground Lug
Terminal Block
Fuse Block (s)
Heating Elements
Surface Mounted
Thermostats with ECO
Surface Mounted Thermostat Models
General Controls Layout
GENERAL INFORMATION

5
600V Surface Thermostat (w/Contactors) Models
General Controls Layout
Ground Lug
Terminal Block
Contactor(s)
Surface Thermostats
Heating Elements
Upper Control Box
High Limit (ECO) Control
Lower Control Box
GENERAL INFORMATION

6
Surface Mounted Thermostats
Surface mounted thermostats are mounted into a bracket above each heating element. The bracket holds the
thermostat against the side of the tank responding to tank surface temperatures to sense a call for heat, set point
temperature and high limit (ECO) activation. As each element has a dedicated thermostat (for all models excluding
600V), it is possible to sequence the elements by varying the settings on the thermostats.
Immersion Style Thermostat Control for
Contactor Models
The thermostat will complete control circuit
voltage upon a call for heat. Likewise, the
control will interrupt control circuit voltage
when the water temperature is sucient to
satisfy the adjustable temperature limit of
control.
Immersion Style High Limit (ECO) Control for
Contactor Models
The high limit (ECO) control will interrupt control
circuit voltage causing the heater to shut down when
the high temperature limit of the control is reached
(196°F ± 4°F). Once the cause for overheated water
has been determined, the control must be manually
reset to restore normal operation.
Surface Mount
Combination Thermostat/
ECO (high limit)
89T Series
Manual ECO (High Limit)
Reset Button
Temperature Control Dial
Direct
Immersion
Bulb
Manual Reset Button
Direct Immersion Bulb
GENERAL INFORMATION

7
GENERAL INFORMATION
Surface Mounted Thermostats (w/Contactors) for 600V Models
600V models use contactors to deliver line voltage to the heating elements. However, rather than the immersion type
high limit and thermostat devices, surface mounted thermostats are used to operate the control circuit of the water
heater.
Surface Mounted
Thermostat
59T Series
Surface Mounted
ECO (High Limit)
Temperature Control Dial Manual Reset Button

8
Contactor
Contactor operation is achieved by energizing an operating coil in response to a call for heat from the immersion
thermostat. Upon a call for heat, one or more contactors will energize all heating elements simultaneously. The
operating coils are voltage specic. When contactor replacement is required be sure to order the proper operating coil
based on the voltage rating found on the rating plate located on the front of the water heater.
Direct Immersion “Screw-in”Type Heating Element
Terminal Connections of
Contactor Operating Coil
Terminal Connections to the
Fuse Block and/or Terminal Block
Terminal Connections to
the Heating Elements
0642
4500W 240V
RC02404524
Terminal Block Screw
1- ½“ Hex
Screw-in Flange Terminal Block
Zinc-plated Copper
or Incoloy Sheath
Element Rating Ink Stamped
on Side of Terminal Block
GENERAL INFORMATION

9
GENERAL INFORMATION
Commonly Used Formulas
(Single Phase)
Amps = Watts
Volts
(Balanced 3 Phase)
Amps = Watts
Volts x 1,732 Ohms = Volts2 Watts
Watts = Amps x Volts
Common Service Wire
Congurations 240V 1Ph
Ungrounded
Ungrounded
Grounding
BLACK
RED
GREEN
240
120
120
120
ABCNeutral
RED BLACK RED
120
120 208
208 208
208 3Ph
120
ABCNeutral
RED BLACK RED
120
120 240
240 240
240 3Ph
277
ABCNeutral
RED BLACK RED
277
277 480
480 480
480 3Ph/277 1Ph
Commonly Used Formulas
208 Volt 240 Volt 277 Volt 380 Volt 415 Volt 480 Volt 600 Volt
kW 1 Phase 3 Phase 1 Phase 3 Phase 1 Phase 3 Phase 3 Phase 1 Phase 3 Phase 3 Phase
6 28.8 16.6 25.0 14.4 21.6 9.1 8.3 12.5 7.2 5.8
9 43.2 25.0 37.2 21.6 32.4 13.6 12.5 18.7 10.8 8.7
12 57.6 33.3 50.0 28.9 43.3 18.2 16.7 25.0 14.4 11.5
13.5 64.9 37.5 56.2 32.5 48.7 20.5 18.8 28.1 16.2 13.0
15 72.1 41.6 62.5 36.1 54.1 22.7 20.9 31.2 18.0 14.4
18 86.5 50.0 75.0 43.4 64.0 27.3 25.0 37.5 21.6 17.3
24 115.4 66.7 100.0 57.8 86.6 36.4 33.4 50.0 28.9 23.1
27 129.8 75.0 112.5 65.0 97.4 41.0 37.5 56.2 32.5 26.0
30 144.2 83.3 125.0 72.2 108.3 45.6 41.7 62.5 36.1 28.9
36 173.0 100.0 150.0 86.7 129.9 54.7 50.1 75.0 43.3 34.6
45 216.3 125.0 187.5 108.3 162.4 68.4 62.6 93.7 54.1 43.3
54 259.6 150.0 225.0 130.0 194.9 82.0 75.1 112.5 65.0 52.0

10
OR Terminal Block
Fuse Block
Line Voltage
Contactor
Contactor
Coil ECO
(High Limit)
T’stat
Heating Elements
Bock’s commercial electric water heaters can use either immersion thermostats (contactor models) or surface mounted
thermostats. Sequence of operation for each conguration is explained below. It would be impractical to show all wire
diagrams applicable to both congurations. A “typical wiring diagram” is illustrated to aid in understanding the principles of
the operating sequence.
Immersion Thermostats (Contactor Models): Congured to use a single immersion thermostat to control one or more
contactors to energize or de-energize all elements simultaneously. In addition, a separate high limit (ECO) control with manual
reset is wired in series with the thermostat. Both controls use a direct immersion bulb inserted into the tank to sense water
temperature. Immersion thermostat and high limit control are mounted to provide temperature adjustment and manual reset
access from the exterior of the unit.
Surface Mounted Thermostats: Surface mounted thermostats are mounted inside the lower control box, in a bracket above
each heating element. The bracket holds the thermostat against the side of the tank, responding to tank surface temperatures
to sense a call for heat, set-point temperature and high limit (ECO) activation. As each element is controlled by a dedicated
thermostat, it is possible to sequence the elements by varying the settings on the thermostat. However, 600V models with
surface mounted thermostats operate contactors in the
same manner as an immersion thermostat model, only using
surface thermostats to sense the call for heat.
Sequence of operation for each system is explained below.
Sequence of Operation:
Immersion Thermostat (Contactor Models).
The system has two distinct circuits:
1. Power Circuit (solid line).
2. Control Circuit (dotted line).
1. Line voltage is applied across terminals of fuse block or a
terminal block. Line voltage continues down and connects
to terminals L1, L2 and L3 of one or more contactors.
A. Contactor is open (no call for heat), so there is no
voltage across terminals T1, T2 and T3 of contactor.
B. The contactor is controlled by the control circuit
consisting of the immersion thermostat, ECO (high
limit) and contactor coil.
2. When the thermostat calls for heat, contacts close inside
the thermostat completing the circuit through the ECO and
energizing the contactor coil.
3. The energized contactor coil causes the contactor to close
energizing the elements from terminals T1, T2 and T3 of the
contactor.
4. When the temperature setting of the thermostat is reached,
the contacts in the thermostat open. This interrupts current
ow through the control circuit de-energizing the contactor
coil.
5. The de-energized contactor coil causes the contactor to
open, interrupting current ow through the elements. The
heater is now in stand-by, waiting for the next call for heat.
SEQUENCE OF OPERATION

11
SEQUENCE OF OPERATION
Terminal Bloc
Fuse Block
Line Voltage
Heating Element
Surface Mounted
Thermostat
1
ECO Closed
Power to one
side of element
2
3
Thermostat closed
at terminal T2
4
Thermostat open
at terminal T2
1. Line voltage is applied across terminals of fuse block or a terminal
block. Line voltage continues down and connects to surface
mounted thermostats at terminals L1 and L3.
2. ECO (high limit) in thermostat is
closed, so there is line voltage
present at terminal L4 of
thermostats and to one side of
each element.
3. Water in the tank is cold, so
all thermostats are closed at
terminal T2 (calling for heat). This
completes the circuit and allows
current to ow through heating
elements.
4. As each thermostat is satised, it
opens at terminal T2, interrupting
current ow through the
respective element. The system
is now in stand-by mode waiting
for the next call for heat.
Sequence of Operation:
Surface Mounted Thermostats.

12
SEQUENCE OF OPERATION
Contactor
Fuse Block
Line Voltage
Heating Elements
High Limit
59T
Transformer
60VA
59T
6 Element Configuration Shown
(9 Elements Possible)
Sequence of Operation:
600V Surface Mounted Thermostats (w/Contactors).
The system has two distinct circuits.
1. Power Circuit - Line Voltage (600V)
2. Control Circuit - 120V
1. Line voltage is applied across terminals of fuse block or a
terminal block. Line voltage continues down and connects
to terminals L1, L2 and L3 of one or more contactors.
A) Contactor is open (no call for heat), so there is no voltage
across terminals T1, T2, and T3 of contactor.
B) The contactor is controlled by the control circuit
consisting of the surface mounted thermostat, ECO (high
limit) and contactor coil.
2. When the thermostat calls for heat, contacts close inside
the thermostat completing the circuit through the ECO and
energizing the contactor coil.
3. The energized contactor coil causes the contactor to close,
energizing the elements from terminals T1, T2 and T3 of the
contactor.
4. When the temperature setting of the thermostat is reached,
the contacts in the thermostat open. This interrupts current
ow through the control circuit de-energizing the contactor
coil.
5. The de-energized contactor coil causes the contactor to
open, interrupting current ow through the elements. The
heater is now in stand-by waiting for the next call for heat.
6. Notice in the wiring diagram at right that each row of
elements is equipped with a surface mounted thermostat
on the highest element in the row. These thermostats are
individually wired in series to the contactor whose line
voltage corresponds to the same row of elements. Each
thermostat and contactor combination are wired to the
ECO in parallel. This allows for each row of elements to
be powered “ON” independent of the other element rows.
However, the ECO is wired in series so that voltage can be
interrupted to the entire control circuit if the ECO senses that
the tank water has become overheated.

13
TROUBLESHOOTING
The most common cause of improper electric water heater operation can be linked to heating element failure.
When troubleshooting an electric water heater with the incidence of“no hot water” or “insucient amount of hot water” it is
always a good idea to check the heating elements rst following the procedure on Page 15.
Common heating element failures are:
1. Dry Firing. Elements may be partially submerged in water or most likely, completely exposed with no water in the tank
at all. In open air, an energized element (dry-red) will become completely inoperable within seconds. In some cases
sediment or lime build up around an element can eventually cause an air pocket, resulting in a dry-red element. When
element replacement is required, be sure tank is full of water prior to energizing the water heater.
2. Grounded Element. In most cases, an element with a short circuit to ground will cause the circuit breaker in the service
panel to open or shut o. In some cases there may not be enough current draw for the circuit breaker to open. This will
allow the heating element to be in continuous operation resulting in overheated water, limited only by the ECO located
in the thermostat circuit. Repeated actuation of the ECO usually is the result of a grounded heating element.
3. Sediment Buildup. Slow hot water recovery can usually be traced back to sediment or lime build-up around heating
element. Sediment build-up can also, over time, cause a dry-red element.
If a heating element is found to be inoperative, it must be replaced. Follow service procedure MCE-XV on Page 30.
The illustration below shows a common “screw-in” type heating element identifying certain features commonly referred to
throughout this manual.
0642
4500W 240V
RC02404524
Terminal Block Screw
1- ½“ Hex
Screw-in Flange Terminal Block Zinc-plated Copper or Incoloy Sheath
Element Rating Ink Stamped
on Side of Terminal Block
Typical Direct Immersion “Screw-In”Type Heating Element

14
TROUBLESHOOTING
Quick Step Plan to Hot Water
1. STOP, DANGER! Turn power“OFF” to water heater.
2. Check all wire connections to insure that they are snug and
corrosion free.
3. Reset high limit (ECO) (Page 18-20).
4. Check for inoperative heating element (Page 15).
5. Check line voltage (Page 16), and internal fuses (Page 17).
6. Refer to table below if items 1 through 5 above do not correct problem.
WARNING
High voltage exposure. Use caution when
making voltage checks to avoid hazard to
life or property.
SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION SERVICE
PROCEDURE
No Hot Water
1. No power to heater.
2. Blown water heater fuses.
3. Loose wire connections.
4. Inoperative heating elements.
5. Inoperative thermostat(s)
6. Open ECO.
7. Inoperative contactor(s).
1. Check circuit breakers at service panel.
2. Check water heater fuses.
3. Check all wire connections.
4. Check heating element(s).
5. Check thermostat(s) operation.
6. Reset (check) ECO.
7. Check contactor operation.
2. III, Page 17
4. I, Page 15
5. VII-IX, Page 21-23
6. IV, VI, Page 18-20
7. X, Page 24-25
Not Enough
Hot Water or
Continues
Operation
1. Inoperative heating element.
2. Sediment or lime buildup on element(s).
3. Thermostat(s) set too low.
4. Inoperative thermostat(s).
5. Inoperative contactor(s).
6. Loose wire connection.
7. High demand period.
8. Undersized heater.
9. Very cold inlet water to heater.
10. Plumbing connections reversed.
1. Check heating element(s).
2. Clean or replace heating element(s).
3. Increase thermostat setting.
4. Check thermostat(s).
5. Check contactor operation.
6. Check all wire connection.
7. Reduce demand.
8. Replace with larger heater.
9. Temper water to heater.
10. Correct plumbing connections.
1. I, Page 15
2. XV, Page 30
4.VII-IX, Page 21-23
5. X, Page 24-25
Slow Hot Water
Recovery
1. Sediment or lime buildup on element(s).
2. Loose wire connections.
3. Inoperative thermostat(s).
4. Inoperative contactor(s).
5. Derated heating element installed.
1. Clean or replace heating elements.
2. Check all wire connections.
3. Check thermostat(s).
4. Check contactor operation.
5. Verify element voltage and wattage rating.
1. XV, Page 30
3. VII-IX, Page 21-23
4. X, Page 24-25
5. See Page 8
Overheated
Water
1. Surface thermostat(s) not ush with tank.
2. Grounded heating element(s).
3. Thermostat set too high.
4. Inoperative thermostat(s).
5. Inoperative ECO.
1. Check surface thermostat(s) mounting.
2. Check heating element(s).
3. Adjust thermostat(s) to desired setting.
4. Check thermostat(s).
5. Check ECO.
1. XI, Page 26
2. IPage 15
4. VII-IX, Page 21-23
5. IV-VI, Page 18-20
Noisy (singing or
hissing) Elements
1. Lime formation on element(s).
2. High or low line voltage.
1. Clean or replace heating element(s).
2. Verify line voltage to heater.
1. XV, Page 30
2. II, Page 16
Noisy Contactor
1. Low line voltage.
2. Debris between contactor plates.
3. Incorrect or defective operating coil.
4. Loose wire connections.
1. Verify line voltage to heater.
2. Replace contactor.
3. Replace contactor.
4. Check wire connections.
1. II, Page 16

15
SERVICE PROCEDURE I
Heating Element Testing
Test for Open or Burned Out Element.
1. STOP, DANGER! Turn power“OFF” to water heater.
2. Remove access cover from lower control box. Remove
insulation from inside of control box.
3. Disconnect wires from heating element.
4. Set multi-meter to “ohms”setting.
5. Touch probes of multi-meter to screw terminals of heating
element (see illustration 1).
6. Reading should be 12.8 ohms (± 6%) for a 240 volt, 4500 watt
element, see table below for other elements.
Ohms = Volts2
Watts
A reading outside the range using the formula
above (± 6%) indicates a bad element and the
element must be replaced.
Ohms of Electrical Resistance
for Commonly Used Elements
Voltage Rating of Element
Element
Wattage 208 240 480
2000 21.6 28.8 115.2
3000 14.4 19.2 76.8
4000 10.8 14.4 57.6
4500 9.6 12.8 51.2
5000 8.7 11.5 46.1
6000 7.2 9.6 38.4
Test for Grounded Heating Element
(Damaged Heating Element with Short Circuit to Ground).
1. STOP, DANGER! Turn power“OFF” to water heater.
2. Remove access cover from lower control box. Remove
insulation from inside of control box.
3. Disconnect wires from heating element.
4. Set multi-meter to “ohms”setting.
5. Touch one probe of multi-meter to either screw terminal
of heating element and the other on the element ange
(see illustration 2). There should be no reading on the ohm
meter. Any reading indicates a grounded element and the
element must be replaced. Repeat this step for the other
screw terminal.
WARNING
High voltage exposure. To avoid hazard
to life or property, be sure power is turned
OFF to water heater while performing this
procedure.
Element Screw Terminals
Element
Screw Terminal
Element Flange
Illustration 1
Illustration 2
NOTE
Disconnect
Element
Wires
NOTE
Disconnect
Element
Wires

16
SERVICE PROCEDURE II
Line Voltage Testing
Line Voltage Testing.
Line voltage (single phase or three phase) will connect to a
terminal block or directly to a fuse block located inside the
control panel.
Determine heaters voltage and phase by referring to the
rating plate located on the front of the water heater. Apply the
appropriate phase procedure below to determine if proper line
voltage is present.
Single Phase Line Voltage Testing.
1. STOP, DANGER! Turn power“OFF” to water heater.
2. Open upper control panel door.
3. Determine connection point for line voltage from service
panel, terminal block or fuse block.
4. Set multi-meter to volts AC. Be sure to scale meter for
appropriate voltage.
5. Use caution and turn power“ON” to water heater.
6. Use caution and check voltage across top terminals where
service voltage connects to water heater (see illustration 3).
A) Rated voltage IS present, power to the water heater is
okay.
B) Rated voltage NOT present, check service panel.
Three Phase Line Voltage Testing.
1. STOP, DANGER! Turn power“OFF” to water heater.
2. Open upper control panel door.
3. Determine connection point for line voltage from service
panel, terminal block or fuse block.
4. Set multi-meter to volts AC. Be sure to scale meter for
appropriate voltage.
5. Use caution and turn power“ON” to water heater.
6. Use caution and check voltage across top terminals where
service voltage connects to water heater (see illustration 4).
A) Rated voltage IS present, power to the water heater is
okay.
B) Rated voltage NOT present, check service panel.
WARNING
High voltage exposure. To avoid hazard to
life or property, use extreme caution when
making voltage checks.
Check voltage across
top terminals.
Line voltage from
service panel
connected to Terminal block
of heater
Line voltage from
service panel
connected to Fuse block
of heater
OR
Line voltage from
service panel
connected to Terminal block
of heater
Line voltage from
service panel
connected to Fuse block
of heater
OR
Check voltage across
top terminals.
Illustration 3
Illustration 4

17
SERVICE PROCEDURE III
Fuse Testing
Fuse Testing.
1. STOP, DANGER! Turn power“OFF” to water heater.
2. Open upper control box to allow access to fuse block.
3. Locate fuse block and remove fuses.
4. Set multi-meter to the ohms setting.
5. Check continuity across fuse (see illustration 5).
A) Continuity IS present, fuse is okay.
B) Continuity NOT present, replace fuse.
WARNING
High voltage exposure. To avoid hazard
to life or property, be sure power is turned
OFF to water heater while performing this
procedure.
Illustration 5

18
SERVICE PROCEDURE IV
High Limit (ECO) Testing
High Limit Control (ECO) Testing for
Surface Thermostat Models (NOT including 600V)
1. This procedure assumes line voltage and fuses are in working
order.
2. This procedure illustrates testing of just one surface thermostat. Repeat this
procedure for all surface thermostats on the water heater.
3. Turn power“OFF” to water heater.
4. Remove lower control box cover and remove insulation from inside of control box.
5. Remove plastic cover from thermostat(s).
6. Turn power“ON” to water heater.
7. Use caution and check voltage across terminals L1 and L4 for all thermostats (see
illustration 6).
A) Rated voltage IS present, ECO is okay.
B) Rated voltage NOT present, proceed to step 8.
8. Turn power“OFF” to water heater and rmly press ECO reset button on thermostat(s).
Turn power “ON”to water heater and recheck voltage across terminals L1 and L4 of thermostat(s).
A) Rated voltage IS present, the ECO has previously opened indicating the water in the tank, at some point, did overheat.
Check the following:
1. Thermostat must be in full contact with tank.
2. Be sure heating element(s) is not shorted to ground (see Page 15).
3. Proper thermostat operation (see Page 21).
B) Rated voltage NOT present, water in tank may be overheated.
1. If water is overheated, turn “OFF”power to water heater and ow water through tank to cool below set point of
upper thermostat. Reset ECO and recheck voltage.
2. If water is cool, replace thermostat(s).
WARNING
High voltage exposure. To avoid hazard to
life or property, use extreme caution when
making voltage checks.
Illustration 6
ECO reset
button
ELEMENT

19
SERVICE PROCEDURE V
High Limit (ECO) Testing
High Limit Control (ECO) Testing for
600V Surface Thermostat Models.
1. This procedure assumes line voltage, transformer, fuses and
thermostat are in working order.
2. Turn power“OFF” to water heater.
3. Remove lower control box cover and remove insulation from inside of control box.
4. Use caution and check continuity across terminals 1 and 2 (see illustration 7).
A) Continuity IS present, ECO is okay.
B) Continuity NOT present, proceed to step 5.
5. Turn power“OFF” to water heater and rmly press ECO reset button on
thermostat(s). Turn power “ON” to water heater and recheck continuity across
terminals 1 and 2 of thermostat(s).
A) Continuity IS present, the ECO has previously opened indicating the water in
the tank, at some point, did overheat. Check the following:
1. Thermostat must be in full contact with tank.
2. Be sure heating element(s) is not shorted to ground (see Page 15).
3. Proper thermostat operation (see Page 22).
B) Continuity NOT present, water in tank may be overheated.
1. If water is overheated, turn “OFF”power to water heater and ow water through tank to cool below set point of
upper thermostat. Reset ECO and recheck continuity.
2. If water is cool, replace ECO.
WARNING
High voltage exposure. To avoid hazard to
life or property, use extreme caution when
making voltage checks.
Illustration 7
ECO reset
button

20
SERVICE PROCEDURE VI
High Limit (ECO) Testing
High Limit Control (ECO) Testing for
Contactor Models
Switch Contacts:
Normally closed.
Open on rise @ 196°F ± 4°F.
Manual Reset.
1. Determine of high limit (ECO) has actuated. This can be done
by simply depressing the reset buttons. If you hear and/or feel
a small click, the switch has actuated.
2. Use caution and turn power on to water heater and observe
heating cycle following the high limit heating cycle ow chart.
High Limit Control Continuity Testing for
Contactor Models
1. STOP, DANGER! Turn power“OFF” to water heater.
2. Water temperature must be below 196°F ± 4°F.
3. Remove high limit switch from control panel. It is not necessary
to remove immersion bulb from tank at this time. See general
controls layout on Page 4 for location.
4. Disconnect wire leads to high limit control during this test.
5. Depress reset buttons to insure switch contacts are closed.
6. Set multi-meter to ohms setting. Check continuity through
circuit A and B as showing in the illustrations below.
A) Continuity IS present, switch is okay.
B) Continuity NOT present, replace switch.
WARNING
High voltage exposure. To avoid hazard
to life or property, be sure power is turned
OFF to water heater while performing this
procedure.
NOTE
Disconnect
Wire Leads to Control
Circuit “A” Continuity Testing Circuit “B” Continuity Testing
Observe heating cycle.
Does switch open?
Is water temperature
over 196°F?
N
N
Y
Y
Y
Is water temperature
over 196°F? Switch OK.
Replace switch.
High Limit Heating Cycle Flow Chart