Bock Water heaters 38W-155 User manual

Energy Saver
COMMERCIAL 24 VOLT FLUE DAMPER
SERIES WATER HEATER
ATMOSPHERIC GAS WATER HEATERS
SERVICE
MANUAL
Troubleshooting Guide and
Instructions for Service
(To be performed ONLY by
qualied service providers)
Models Covered
by This Manual:
For the Bock Water Heaters
“W” Series Models:
38W-155
75W-(125, 160, 300)
66W-(370, 399)
80W-(180, 199, 250)
80W-(425, 450, 505)
100W-(199, 250, 270, 300)
Manual 47324A Save this manual for future reference.

2
W-Series
Atmospheric Gas
Table of Contents
Service
Page Procedure
Introduction 3 - - -
Tools Required for Service 3 - - -
Sequence of Operation 4 - - -
Troubleshooting 5 - - -
Thermostat Circuit Testing 6 24-I
Pilot Operation Testing 8 24-II
Main Burner Operation Testing 10 24-III
Main Burner and Pilot Removal and Inspection 12 24-IV
Flue Baffle Removal and Inspection 14 24-V
Anode Removal and Inspection 15 24-VI
Generic Parts List 16 - - -
Glossary of Terms/Notes 19 - - -

3
W-Series Introduction
It is intended for this manual to be used by qualied service personal for the primary purpose of
troubleshooting, analysis, and repair of the Bock 24 Volt Flue Damper W-Series Water Heater.
Understanding the “Sequence of Operation” section of this manual will contribute greatly to
troubleshooting this product.
Troubleshooting begins simply by resetting the water heater and observing the lighting sequence
to determine failure mode. This step-by-step procedure beginning on Page 5 will direct the service
provider to a series of test procedures to determine the root cause of failure.
Contact Technical Support immediately if diagnosis is not determined using the methods described
in this service manual.
Tools Required for Service
Manometer: Two types available, a liquid “U” tube type or a digital (magna-helic) type.
This device is used to measure gas and/or air pressures and vacuum.
Multi-Meter: A digital type is strongly recommended. This device is used to measure
electrical values. The meter you select must have the capability to
measure volts AC, volts DC, amps, micro amps and ohms.
Thermometer: Used to measure water temperature. An accurate thermometer is
recommended.
Water Pressure Gauge: Used to measure water supply pressure. Also used to determine tank
pressure by adapting to the drain valve of the heater.
Jumper Leads: A length of wire (12” min.) with alligator clip at both ends.
Various Hand Tools: Pipe wrench, channel locks, open-end wrench set, 12” crescent wrench,
allen wrench set, torx bit set, screw drivers (common and phillips), long
reach (12”) magnetic tip phillips head screw driver #2 tip, ¼” nut driver,
pliers (common and needle nose), socket set including a 1 - 1/16” deep
well socket, wire cutters, wire strippers, wire crimpers, torpedo level, small
shop vac, step ladder, and ashlight.

4
W-Series Sequence of Operation
WIRING DIAGRAM
1. Thermostat calls for heat. The relay closes on the thermostat board, sending 24 volts from the
“COM” terminal of the thermostat board to the ue damper.
2. Flue damper begins to rotate open. Once damper is full open, 24 volts is allowed to continue through
damper to the “TH” terminal of ignition module.
3. LED on ignition module illuminates.
4. Trial for ignition (90 second trials, 3 trials with 30 second pause between trials)
Ignition module simultaneously sends:
1. 24 volts from “MV/PV” terminal, to “MV/PV”
terminal of gas valve (common terminal).
2. 24 volts from “PV” terminal, through the ECO
located in the lower thermister, to “PV” terminal of
gas valve to establish gas ow at pilot.
3. Low current high voltage from “spark” terminal,
to generate spark at the pilot and ignite pilot gas
ow.
4. Pilot ame proving signal (measured in micro
amps) from the “sense” terminal, to prove pilot
ame.
5. Once pilot ame is proven, spark will stop.
6. Once spark stops, 24 volts is sent from “MV” terminal on
module, to “MV” terminal on gas valve to establish main
burner gas ow. Main burners ignite from the pilot ame.
The ignition module constantly monitors pilot ame. If the
pilot ame is lost, pilot and main burner are shut down.
After a 30 second purge period, module will attempt to
re-light pilot beginning at sequence 4 above.
7. Main burner res until the thermostat is satised. The
relay on the thermostat board opens, interrupting 24 volts
through the damper and ignition module. Pilot and main
burner are turned off.
8. Flue damper rotates to the closed position.
LOCKOUT CONDITION
Ignition module will “lockout” if the pilot cannot be lit after 3 ignition trials. The ignition module indicates a
lockout condition by the continuing ash of the LED located on the module.
Lockout reset is accomplished by interrupting 120 VAC to the unit for at least 5 seconds.

5
W-Series Troubleshooting
Verify primary and secondary
voltage at the transformer.
(see photo 1)
If LED on ignition module is
ashing, reset water heater by turning
“OFF” power. Wait 5 seconds and turn
power back “on”.
Rotate thermostat dial to the
highest setting.
Does damper vane move to the full
open position?
Does LED light on ignition module
illuminate?
Is there pilot ame?
Does main burner operate?
Does burner continue until
thermostat set point is reached?
Does ue damper rotate to the
closed position?
System okay.
Remove damper from
heater and jump black
& yellow wires of heater
harness.
(see photo 2)
Does LED light on
ignition module
illuminate?
Check for debris limiting
damper rotation. If no
debris, replace damper.
See “thermostat testing.”
(page 6)
Is there 24 VAC between
terminals “TR” & “TH” of the
ignition module?
(see photo 1A)
See “pilot will not light.”
(page 8)
See “pilot lights,
no ame signal.”
(page 9)
See “main burner
short cycle.”
(page 11)
Check for debris limiting
damper rotation. If no
debris, replace damper.
Replace ignition module
Check damper
harness connection
CAUTION
Use Caution Not to Damage Connectors When Making Voltage Measurements or Jumping Terminals.
Y
Y
Y
Y
Y
Y
Y
Y
N
N
N
N
N
N
N
N
1
DANGER
120 Volt Exposure. Use Caution
to Avoid Personal Injury
1A
2
Rear Terminals
primary
(120 VAC)
Forward Terminals
primary
(24 VAC)
Ignition Module
Ignition Module LED Status
OFF = No power to module
ON = Module has power
Flashing = Module is in lock-out
Check for 24 VAC
across terminals
“TR” & “TH”
Damper vane shown in open position. If damper
is closed, disconnect from harness and
REMOVE damper from water heater.
Harness shown disconnected from damper
with BLACK and YELLOW wires jumped.

6
W-Series Service Procedure 24-I
Thermostat Circuit Testing
3
4
5
7
6
8
DANGER
120 Volt Exposure. To avoid personal injury,
use caution while performing this procedure.
CAUTION
Be careful when making voltage
measurements or jumping terminals
not to damage or deform connectors or
connector pins.
DANGER
Do not leave thermostat jumper in
place for normal operations.
This procedure assumes the ue damper is in working order. Be sure damper opens under its own power when the
thermostat circuit is bypassed. Damper must be open or removed during this test. Do not force damper open using your
hands or tools.
With power on to water heater, verify
primary and secondary voltage at
the transformer.
(see photo 3)
THERMOSTAT CIRCUIT BYPASS
Turn power “OFF” to water heater and
locate thermostat board inside control box
of water heater. Disconnect YELLOW wires
from the thermostat board at location
“N.O.” & “COM.” Use a jumper to connect
these two wires together.
(see photos 4 & 5)
Turn power on to water heater.
Does LED on ignition module illuminate?
(see photo 6)
Does pilot and main burner operate?
Turn power “OFF.”
Remove jumper and reconnect wires to
thermostat board. Wires are identied for
proper connection to board.
Disconnect ORANGE potentiometer (temp
adjustment dial) wires from thermostat
board. (see photo 7)
Check potentiometer for proper resistance values of:
Greater than 4800 Ohms with dial at minimum setting.
Less than 50 Ohms with dial at maximum setting.
(see photo 8)
Are readings correct?
Replace potentiometer.
Check thermisters.
(see page 7)
Verify transformer voltage.
(see photo 3)
See pilot operation testing.
(page 8)
Rear
Terminals
Primary
(120 VAC)
Forward Terminals
Secondary
(24 VAC)
LED Location
Y
Y
Y
N
N
N

7
W-Series Service Procedure 24-I
Thermostat Circuit Testing
Thermister Resistance at Various Temperatures
Example: If water temperature is 84°F, then the resistance through the sensor would be 8449 (see shaded area).
Note: Sensor resistance increases as the temperature falls.
In Degrees F
°F 0 1 2 3 4 5 6 7 8 9
40 26109 25400 24712 24045 23399 22771 22163 21573 21000 20445
50 19906 19383 18876 18383 17905 17440 16990 16553 16128 15715
60 15314 14925 14548 14180 13823 13477 13140 12812 12494 12185
70 11884 11592 11308 11032 10763 10502 10248 10000 9760 9526
80 9299 9078 8862 8653 8449 8250 8057 7869 7685 7507
90 7333 7165 7000 6839 6683 6531 6383 6238 6098 5961
100 5827 5697 5570 5546 5326 5208 5094 4982 4873 4767
110 4663 4562 4464 4368 4274 4183 4094 4006 3922 3839
120 3758 3679 3602 3527 3453 3382 3312 3244 3177 3112
130 3048 2986 2925 2866 2808 2752 2697 2643 2590 2538
140 2488 2439 2391 2344 2298 2253 2209 2166 2124 2083
150 2043 2004 1966 1928 1891 1856 1820 1786 1753 1720
160 1688 1656 1625 1595 1566 1537 1509 1481 1454 1427
170 1402 1376 1351 1327 1303 1280 1257 1235 1213 1191
180 1170 1150 1129 1110 1090 1071 1053 1035 1017 999
190 982 965 949 933 917 901 886 871 857 842
200 828 814 801 788 775 762 749 737 725 713
9
10
Are readings
correct?
Replace
thermister.
Replace
harness.
Check harness
continuity.
Continuity okay?
Replace
thermostat board.
Thermister Resistance Testing
Upper Thermister:
1. Determine resistance value of upper thermister. Test across
grey wires. (see photo 9)
2. Draw quart of water off T&P valve. Using a thermometer
determine water temperature
3. Use table below to verify correct resistance per water
temperature measured.
Lower Thermister:
1. Determine resistance value of lower thermister. Test across
blue wires. (See photo 10)
2. Draw quarter of water off Drain Valve. Using a thermometer
determine water temperature.
3. Use table below to verify correct resistance per water
temperature measured.
Upper thermister location
(applicable models)
Lower thermister access
located inside control box
Y
Y
N
N

8
W-Series Service Procedure 24-II
Pilot Operation Testing
DANGER
120 Volt Exposure. To avoid personal injury,
use caution while performing this procedure.
CAUTION
Be careful when making voltage
measurements or jumping terminals
not to damage or deform connectors or
connector pins.
11
12
13
Condition
Pilot will not light.
Ignition module LED is “ON”.
Reset heater by turning
power “OFF.” Wait 5 seconds and
turn power “ON.” When LED of
ignition module turns “ON” does
ignition module send “spark” signal
(buzzing or clicking sound)?
Is there spark at the pilot?
Is there 22-27 VAC output
across terminals “MV/PV” & “PV”
of ignition module? Disconnect
wires and check across terminal of
module. (see photo 11)
Is there 22-27 VAC input
across wire leads “MV/PV” and
“PV” at gas valve?
(see photo 12)
Check continuity across ECO
(RED) leads of lower thermister.
(see photo 13)
Is continuity okay?
Check wire harness for damage
or loose connections. Repair or
replace as needed.
Replace ignition module.
Replace ignition module.
Loosen pilot tubing connection
at the gas valve and soap test.
Is there pilot gas ow out of the
gas valve?
Tighten pilot tube connection at
the gas valve. Check incoming
gas pressure to water heater.
If okay, replace gas valve.
Check for:
Loose or damaged ignition wire,
grounded pilot electrode,
damaged pilot.
Check for clogged or kinked
pilot tube, clogged pilot orice.
Clean or replace as needed.
(see page 13)
ECO Specications
Opens between 181°F/201°F
Closes between 160°F/100°F
Check across
“MV/PV” and “PV” terminals.
Check across
“MV/PV” and “PV” wire leads
to gas valve.
Check across RED
wire leads of lower
thermister (ECO).
Y
Y
Y
Y
N
N
N
N
Y Y
N

9
W-Series Service Procedure 24-II
Pilot Operation Testing
DANGER
120 Volt Exposure. To avoid personal injury,
use caution while performing this procedure.
CAUTION
Be careful when making voltage
measurements or jumping terminals
not to damage or deform connectors or
connector pins.
Condition:
Pilot lights, no ame signal.
Module continues to spark until
system “Lock Out.” Main burner
will not light
Check for loose or damaged ame
sense lead from pilot to module.
(see illustration 1)
Is ame sense lead okay?
Check for loose or damaged ground
wire(s). Are ground wires okay?
Check venting conditions for
negative pressure
Is vent system okay?
Is heater condensing causing
pilot interruption?
Determine cause for condensing
and correct. Possible causes:
undersized heater or
high demand periods.
Disconnect white ame sense
lead from ignition module at the
“SENSE” location. Set multi-meter
to the “Micro Amps” setting (µA)
(see note). Check micro amp
reading. Be sure module is
sparking during this test.
(see illustration 2)
NOTE:
If multi-meter is not capable
of testing micro amps, check
continuity of sense lead. If no
continuity, clean pilot ame
rod or replace pilot.
(see illustration 3)
Micro Amp Readings
0.000 Micro Amps = Replace module.
1.0 Micro Amps or Less = Clean pilot ame rod or replace pilot.
Repair wire lead or replace pilot.
Repair ground wire(s) or
replace as needed.
Correct improper venting condition.
White Flame Sense
Lead from Pilot
Flame Rod
Flame Rod
Flame Rod
White Wire Lead
from Pilot
Meter
Probe
Meter
Probe
Meter
Probe
Multi-meter
set to check
continuity.
Meter
Probe
Illustration 1
Illustration 2
Illustration 3
Y
Y
Y
Y
N
N
N
N
Multi-meter set to
MicroAmp Setting
(µA)

10
W-Series Service Procedure 24-
III
Main Burner Operation Testing
DANGER
120 Volt Exposure. To avoid personal injury,
use caution while performing this procedure.
CAUTION
Be careful when making voltage
measurements or jumping terminals
not to damage or deform connectors or
connector pins.
14
15
Condition:
Main burner will not light.
Ignition module LED is “ON”
Is pilot lit? See “pilot will not light.” (page 8)
Does module continue to
spark with pilot lit?
See “pilot lights, no ame signal.”
(page 9)
Disconnect “brown” wire from
“MV” terminal of ignition module.
Is there 22-27 volts AC across
“MV” terminal of ignition module and
ground? (see photo 14)
Be sure module LED is “ON”,
pilot is lit and module is not sparking.
Recheck voltage across “MV Terminal
of ignition module and ground.
Is voltage present?
Replace ignition module.
Disconnect “brown” wire lead
from “MV terminal of gas valve.
Is there 22-27 volts AC across
“brown wire lead and ground?
(see photo 15)
Check incoming gas pressure to
gas valve. If okay replace
gas valve.
Reconnect brown wire
to ignition module.
Check wire harness for damage
or loose connections. Repair or
replace as needed.
Ground Disconnect “brown”
wire from “MV”
location of ignition
module.
Check voltage from
“MV” terminal of
ignition module and
ground.
Brown wire disconnected from
“MV” terminal of gas valve Ground lug of gas valve
Y
Y
Y
Y
Y
N
N
N N
N

W-Series
11
Service Procedure 24- III
Main Burner Operation Testing
DANGER
120 Volt Exposure. To avoid personal injury,
use caution while performing this procedure.
CAUTION
Be careful when making voltage
measurements or jumping terminals
not to damage or deform connectors or
connector pins.
16
Condition:
Main burner short cycle.
Check gas (line) pressure to
the water heater. Minimum line
pressure should be 5.5” W.C.
Is gas pressure within proper
specication? (see photo 16)
Check venting conditions, i.e.
clogged vent, down drafts or
negative building pressure. Is vent
system okay?
Is sufcient combustion air being
supplied to the water heater?
Check for unstable pilot ame or
oxidized ame rod on pilot causing
weak pilot signal. (see page 9)
Check burner tubes for scale or
debris buildup. Clean burner as
necessary. (see page 12)
Check tank ues for blockage or
debris buildup causing restriction.
(see page 14)
Determine cause of incorrect gas
pressure and correct.
Correct improper venting condition.
Provide proper combustion air to
water heater.
Line Gas
Pressure Port
Manifold
Pressure Port
N
N
Y
Y

12
W-Series Service Procedure 24-IV
Main Burner & Pilot
Removal and Inspection
WARNING
Heater components may be HOT when performing the following steps in this procedure.
Take necessary precaution to prevent injury.
Main Burner Removal
Step 1. Disconnect (unplug) water heater from electric
supply.
Step 2. Turn “OFF” gas supply to water heater.
Step 3. Rotate gas valve control knob to the “OFF”
position. (see photo 17)
Step 4. Disconnect gas supply line from the gas valve.
(see photo 17)
Step 5. Disconnect wire leads from gas valve.
(see photo 17)
Step 6. Disconnect white ame sense wire and orange
ignition wire from ignition module. (see photo 18)
Step 7. Remove the two burner rack mounting screws.
Step 8. Slide complete burner rack out from heater.
(see photo 19)
Step 9. To install burner, reverse above procedure.
Main Burner Inspection
Step 1. Burner tubes should be free of any ue scale or
other debris. Clean burner tubes using a stiff
brush and/or shop vac. Burner ports should have
uniform openings. Replacement is recommended
for burners where port area is deteriorated or
other unintended openings are present.
Step 2. Insure pilot shield is in place. (see photo 20)
Step 3. Inspect pilot position to insure smooth burner
ignition from pilot ame. Pilot should be mounted
using the two mounting screws through the burner
support bracket resulting in a level pilot position.
17
18
19
20
Gas Valve
Control Knob
Gas Supply
Line
Gas Valve
Wire Leads Burner Rack
Mounting
Screw
Pilot Shield
Ignition Wire Flame Sense
Wire

W-Series
13
Service Procedure 24-IV
Main Burner & Pilot
Removal and Inspection
Pilot Burner Removal
Step 1. With burner rack removed from heater, disconnect
pilot tube connection from gas valve.
Step 2. Remove the two pilot burner mounting screws
securing the pilot and pilot shield in place.
Step 3. Remove pilot shield and pilot from burner rack.
Step 4. To install pilot burner and pilot shield, reverse above
procedure. Be sure to reconnect green ground wire.
Pilot Burner Inspection
Step 1. Inspect pilot for the following:
a) Broken or cracked ceramic insulators. If found,
pilot must be replaced.
b) Damaged electrode or ame sense wire. If
found, pilot must be replaced.
c) Oxidation build-up on ame rod. Clean ame rod
or replace pilot as necessary.
Step 2. Inspect pilot orice:
a) Remove 7/16” ferrule nut from bottom of pilot.
b) Remove pilot tube and orice from pilot.
c) Inspect pilot tube for blockage. Clean or replace
as necessary.
d) Inspect pilot orice for blockage. Clean or
replace as necessary.
Pilot Shield
Pilot and Pilot Shield
Mounting Screws
Ground Wire
Location
Flame Rod
Ceramic
Insulators
Ignition
Wire
Flame Sense
Wire
Pilot
Orice
7/16”
Ferrule
Nut

14
W-Series Service Procedure V
Flue Bae Removal & Inspection
WARNING
Heater components may be HOT when performing the following steps in this procedure.
Take necessary precaution to prevent injury.
Step 1. Disconnect (unplug) water heater from electrical supply.
Step 2. Disconnect venting from draft diverter and remove draft diverter from top of water heater.
Step 3. Disconnect ue damper from wire harness and remove ue damper from top of water heater.
Step 4. If required, disconnect top plumbing connection from top of water heater.
Step 5. Remove screws holding jacket head to top of water heater and remove jacket head from top of
water heater.
Step 6. Remove insulation from top of water heater to expose collector cover.
Step 7. Remove screw from side (or top) of collector cover and remove collector cover from water heater.
Step 8. Remove ue bafes from water heater. Note, it may be necessary to use pliers to loosen and
remove bafes from ue tubes.
Step 9. Visually inspect the ue bafes. Flue bafes should show signs of oxidation, this is normal. If
the oxidation has deteriorated any portion of the ue bafe, replacement is recommended. If any
restrictors are missing, replacement is recommended.
Step 10. Upon completion of inspection or subsequent replacement, reinstall ue bafes into water heater.
Step 11. Reinstall collector cover and insulation over collector cover.
Step 12. Reinstall jacket head, ue damper and draft diverter. Reconnect venting.
Step 13. Reconnect plumbing connection to top of water heater if required.

W-Series
15
Service Procedure 24-VI
Anode Removal & Inspection
WARNING
Heater components may be HOT when performing the following steps in this procedure.
Take necessary precaution to prevent injury.
Step 1. Disconnect (unplug) water heater from electrical supply.
Step 2. Turn “OFF” water supply to water heater.
Step 3. Open a nearby hot water faucet to relieve tank pressure.
Step 4. Connect hose to drain valve of water heater and route to an open drain. Open drain valve and
drain approximately 1 gallon of water from the water heater. Close drain valve and disconnect
drain hose from water heater.
Step 5. Disconnect venting from draft diverter and remove draft diverter from top of water heater.
Step 6. Disconnect ue damper from wire harness and remove ue damper from top of water heater.
Step 7. If required, disconnect top plumbing connection from top of water heater.
Step 8. Remove screws holding jacket head to top of water heater and remove jacket head from top of
water heater.
Step 9. Remove insulation from top of water heater to expose collector cover.
Step 10. Remove screw from side (or top) of collector cover and remove collector cover from water heater.
Step 11. Locate and remove anode rods from top of water heater (1-1/16” hex socket).
Step 12. Visually inspect anode rod. Anode rod should show signs of depletion, this is normal. If the
depletion is half the original diameter (approximately 3/4”), replacement is recommended. If any
of the steel core of the anode rod is exposed, replacement is recommended.
Step 13. Upon completion of inspection and/or replacement, reinstall anode rods into the water heater.
Step 14. Reinstall collector cover and insulation over collector cover.
Step 15. Reinstall jacket head, ue damper and draft diverter. Reconnect venting.
Step 16. Reconnect plumbing connection to top of water heater if required.
Step 17. Restore water supply and power to water heater.

16
W-Series Generic Parts List
1
2
3
4
5
6
30
29
28
27
24
26
25
23
22
21
20
7
8
9
10
11
15 15A
17/17A
16/16A
18
19
12
13
14
1. Draft Diverter w/Leg Kit
2. Draft Diverter
3. Draft Diverter Leg
4. Damper Outlet Reducer
5. Flue Damper
6. Hot Outlet Nipple
7. Cold Water Inlet Dip Tube
8. Hex Head Anode
9. Flue Bafe
10. Flue Reducer
11. Flue core
12. 1” x ¾” Reducer Bushing
13. Nipple T&P Valve
14. T&P Valve
15. Cleanout O-Ring
15A. Cleanout Gasket (ASME)
16. Cleanout Access Cover
16A. Cleanout Access Cover (ASME)
17. Cleanout Cover Screw
17A. Cleanout Cover Screw (ASME)
18. Cleanout Jacket Cover
19. Cleanout Jacket Cover Screw
20. Burner Assembly (Complete)
21. Brass Drain Valve
22. Cold Water Inlet Nipple (Side)
23. Gas Valve Harness
24. Damper Harness
25. Lower Thermister
26. Control Box Asmbly (Complete)
27. Hot Water Outlet Nipple (Side)
28. Upper Thermister
29. Utility Cover
30. ASSE Approved Mixing Valve

W-Series
17
Generic Parts List
1A
2A
3A
4A
5A
6A
7A
8A
9A
10A
11A
12A
13A
14A
15A 16A
17A
18A
19A
20A
21A
22A 23A
24A
25A
26A
27A
28A
29A
1A. Draft Panel
2A. Burner Rack
3A. Burner Tube
4A. Gas Valve
5A. Burner Manifold
6A. Main Burner Orice
7A. Pilot Shield
8A. Pilot Burner
9A. Pilot Orice
10A. Pilot Tubing
11A. Pilot Mounting Screw
12A. Burner Tube Support
13A. Manifold Bracket
14A. C-Cane Manifold
15A. Manifold Straight
16A. Manifold Bracket
17A. 90° Street Elbow Black
18A. 1” Down Pipe Nipple Black
19A 1” 90° Elbow Black
20A. 1” Manifold Ball Valve
21A. 1” Close Nipple Black
22A. Pilot Regulator
23A. Pilot Solenoid
24A 1/8” Pipe Plug Black
25A 1” x 1/8” Reducer Bushing
26A. 1” Pipe Tee Black
27A 1” Close Nipple Black
28A. 1” Union Black
29A. 1” 90° Elbow Black

18
W-Series Generic Parts List
1C
2C
3C
4C
5C
6C
7C
8C
9C
10C 11C 12C
13C
14C
15C
16C
1C. Temperature Control Knob
2C. Potentiometer Gasket
3C. Potentiometer (Temperature Control)
4C. 7/8” Snap Bushing
5C. Temperature Scale Plate
6C. Control Box Panel
7C. Terminal Strip
8C. Ground Terminal
9C. Power Cord Train Relief Bushing
10C. Power Cord
11C. Pilot Wire Strain Relief Bushing
12C. 7/8” Snap Bushing
13C. Transformer
14C. Thermostat Board
15C. Ignition Module
16C. Control Box Cover

W-Series
19
Glossary of Terms
AC Alternating Current
BTU/H British Thermal Units
CO Carbon Monoxide
CO2 Carbon Dioxide
DC Direct Current
ECO Energy Cut Off
GFI Ground Fault Interrupt
GPM Gallons per Minute
Hz Hertz
LED Light Emitting Diode
NOx Oxides of Nitrogen
NPT National Pipe Thread
PSI Pounds per Square Inch
VA Volt Amps
VAC Volts Alternating Current
W.C. Inches of Water Column
°C Degrees Centigrade
°F Degrees Fahrenheit
µA Micro Amp
NOTES

Madison, Wisconsin
For U.S. and Canada eld service,
contact your professional installer or
local Bock Water Heaters sales representative
Sales/608-227-3311
Fax/608-327-3311
Application & Sizing/608-227-3311
Fax/608-327-3311
Technical Support/888-784-8322
Fax/610-683-9208
Warranty/608-227-3319
Fax/608-327-3300
Email
[email protected]
www.bockwaterheaters.com