Bradford White D-80T-199-3N, D-100T-250-3NA, D-100S-199-3N, D-80T-180-3N, D-38T-155-3N+ User Manual

COMMERCIAL 24 VOLT FLUE DAMPER

SERIES WATER HEATER WITH HONEYWELL

INTEGRATED CONTROL SYSTEM

Gas Water Heaters

SERVICE

MANUAL

Troubleshooting Guide

and Instructions for Service

(To be performed ONLY by

qualified service providers)

Manual 47985A REV 08/18

Models Covered

by This Manual:

For The Bradford White
“D” Series Models:
D38T155
D75T(125,160,300)
D65T(370,399)
D80T(180,199,250)
D80T(425,505)
D100T(199,250)
D80L(399,450,505)
D100L(199,250,270,300)
D100S(199,250)

Save this manual for future reference

Table of Contents

Page Service Procedure

Introduction 4 - - -

Tools Required for Service 4 - - -

Sequence of Operation 6 - - -

Troubleshooting 7 - - -

Thermostat Circuit Testing 24 D24-I

Pilot Operation Testing 27 D24-II

Main Burner Operation Testing 30 D24-III

Main Burner & Pilot Removal & Inspection 32 D24-IV

Flue Baffle Removal & Inspection 35 D24-V

Anode Removal & Inspection 36 D24-VI

Generic Parts List 38 - - -

Glossary of Terms 41 - - -

Notes 41 - - -

Page 2

2

FEATURES OF HONEYWELL INTEGRATED CONTROLS SYSTEM

Attractive digital water heater display on control panel for setting and displaying
the temperature setpoint. Pressing temperature up and down buttons changes
the temperature setpoint. Temperature format may be displayed in degrees F or
degrees C.

Single control board with plug in wiring controls temperature, ignition, and flue
damper operation.

Reduced number of parts for servicing and wiring.

Plug in wiring reduces chance of miswiring.

Water heater display will show diagnostic codes in the event the water heater
needs servicing. Aids in diagnosing and servicing the water heater.

Water heater display can show up to 10 previous error codes in the service mode
to further aid in servicing the water heater.

Page 3

3

Tools Required for Service

It is intended for this manual to be used by qualified service personnel for the primary purpose of
troubleshooting analysis and repair of the Bradford White 24 Volt Flue Damper Series Water
Heater. Understanding the sequence of operation section of this manual will contribute greatly to
troubleshooting this product.

Troubleshooting begins by noting the error code, if any, on the water heater control display and
finding the section in this service manual for diagnosing the problem for this error code. This step
by step procedure beginning on page 5 will direct the service provider to a series of test
procedures to determine root cause of failure.

Contact Technical support immediately if diagnosis is not determined using the methods described
in this service manual.

Page 4

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 Gage: 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 & phillips), long
reach (12") magnetic tip phillips head screw driver #2 tip, ¼" nut driver,
pliers (common & 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 flashlight.

Introduction

4

Power Supply Dedicated 120 VAC, 60 Hz., 15 A

Current Draw Less than 5 Amps.

Approved Gas Type Natural or Propane. Gas supply must match the gas type listed on the water

heater rating label.

Gas Supply Connection 1" NPT connection to gas valve for 370,000 Btu/hr. and over for natural gas,

¾" NPT for rest. Schedule 40 black iron pipe recommended.

Gas Pressure (Nat. & L.P.) Manifold Pressure: 4.5" w.c. natural gas, 10.0" w.c. L.P. Gas Supply

Pressure: At least 1" above manifold pressure with water heater operating,
14" w.c. maximum.

Venting System Atmospherically Vented, Type B venting system or approved chimney. Follow

current National Fuel Gas Code requirements or in Canada, the Natural Gas
and Propane Installation Code.

Minimum Clearance for Servicing 24" Front Clearance, 20" Top, 6" Sides.

Maximum Water Supply Pressure 150 PSI.

Thermostat Sensor(s) Redundant thermister with 11,900 + or - 0.5% ohms resistance at 70 deg. F.

Sensor inside well for lower sensor. Some models use an additional upper
sensor (w/o well) with same resistance values.

Control Board Honeywell Integrated Control Board for Temperature Control, Flue Damper,

and Ignition Control Functions. Operates on 24 volts AC current from
transformer. Some models use single sensor boards, others use two
sensors.

Control Display Honeywell LCD Control Display with Temperature Setpoint, Format, and Error

Code Display in User Mode, Diagnostic Functions in Service Mode.
Communicates with Control Board.

Transformer 120 VAC Primary, 24 VAC Secondary, 40 VA.

Pilot Intermittent Pilot with Spark Electrode and Flame Sensor monitored by Control

Board.

Flue Damper 24 VAC, 60 Hz., 80 Ma.

Page 5

Specifications

5

1

Thermostat calls for heat.
The control board sends 24 volts from damper terminal #2 on the control plug
to the flue damper.

2

Flue damper begins to rotate open. Once the flue damper is fully open, the damper end switch closes and 24 volts
is allowed to continue through damper to damper pin terminal #5.

3

4

Once pilot flame is proven, sparking will stop.

Page 6

Sequence of Operation

T

rial for ignition (three 90 second ignition trials, with 65 second pauses

between trials).

Control Board simultaneously sends:

1. 24 volts from control pin terminal #8, to “MV/PV”
terminal of gas valve (common terminal).

2. 24 volts from control pin terminal #2, to “PV”
terminal of gas valve to establish

gas flow at pilot.

3. Low current high voltage from “spark”
terminal, to generate spark at the pilot and
ignite pilot gas flow.

4. Pilot flame proving signal (measured in
micro-amps). from the “sense” terminal, to
prove pilot flame.

5

Once sparking stops, 24 volts is sent from control pin
terminal #5 on control board, to “MV” terminal on gas valve
to establish main burner gas flow. Main burners ignite from
the pilot flame.

The control board constantly monitors pilot flame through
the flame sensor rod. If pilot flame is lost, pilot and main
burners are shut down. After a 65 second inter-purge
period, the control will attempt to re-light the pilot beginning
at sequence 3 above.

7

Main burner fires until the thermostat is satisfied. The control
board interrupts 24 volts through the damper and the gas valve
circuit. Pilot and main burners are turned off.

8

Flue damper rotates to the closed position.

WIRING DIAGRAM

LOCKOUT CONDITION

Control board will go into “Soft Lockout” if the pilot cannot be lit
after 3 ignition trials. The water heater display indicates a lockout
condition by showing an error code number (62 or 63) with
“Service Needed” in the display window. Refer to error codes in
the diagnostic section of this Service Manual. In a “Soft Lockout”
condition, the control will wait for 60 minutes and then make 3
more attempts to light the pilot and establish the main burners.

Soft lockout reset is accomplished by depressing the lower right
button under “Reset” for 3 seconds.

If the water heater should reach 200 degrees F, then the high limit
control will shut off the burners and the water heater will go into a
“Hard Lockout”. Error code 65 will be shown in the water heater
display. The control can only be reset in the “service mode”,
which is detailed in the next section of this Service Manual.

6

CAUTION

Use Caution Not to Damage Connectors when making Voltage Measurements or Jumping Terminals

Water Heater Fault: Water heater does not operate
Display Error Code: Water heater display does not operate - blank display

Check main power supply to water

heater - fuse, circuit breaker, plug

receptacle, line cord or wiring to

water heater.

C

heck to make sure switch on top of
c

ontrol panel is in the ON position

Verify Primary and Secondary

voltage at the control board.

Voltage at primary pins 1&3 (white and
black wires) should be 110-120. If not,

check Line In pins 1&4. Check line cord

with ohmeter. Replace line cord if

defective.

If there is not 24 volts at Secondary

pins on the control board, check

transformer. Replace transformer

or wire harness.

Does water heater display operate?

Does damper begin to open?

Increase thermostat setting if tank is

warm and make sure the control

display status reads “Heating”.

Check wire connections of

board to display. See

illustration.

With the control cover tilted down,

measure the voltage between red and

black wire pin connections to display.

Voltage should be 24 volts AC

measured at the back of the Control

Display.

If no voltage at Display, check wire

harnesses and voltage at E-com

screw terminals (see photo 5).

Replace display if voltage is present at

display pin terminals. Replace control

board if no voltage is present at E-

com terminals (1&3, white-black wires

and 1&2, white-red wires) to display.

N

Y

See next page

Checking primary voltage to

transformer from board. Pins to

black and white wires.

Checking line voltage to board.

Pins to black and white wires.

Checking secondary voltage from

transformer. Pins to blue and yellow

wires.

Checking transformer voltage, front

terminals are 24 volts, rear terminals

are 120 volts.

Page 7

Troubleshooting

1 2

3

4

5

7

Does damper blade move to the full

open position?

Error code #55 on display.

R

emove damper from heater and

jump black & yellow wires of

heater harness. Refer to photo on

this page.

Does wat er heater beg in to

operate?

Check for debris limiting da mper

rotation. If no debris, repl ace

damper.

I

s there pilot flame?

Error code #62 on dis play. See

“Pilot Will Not Light”.

Does Main Burner operate?

Error code #62 on dis play. See

“Pilot Lights, No Flame Signal”

Does burner c ontinue until

thermostat set point is reached?

See setting display in Service Mode

and displaying temperat ure

sensors.

Error code #63 on dis play. See

“Main Burner Short Cycl es”.

Does the flue damper rot ate to the

fully closed position?

Error code #56 on display.

Check for debris limiting damper

rotation. If no debris, repl ace

damper

System okay

Damper vane show 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.

CAUTION

Use Caution Not to Damage Connectors when making Voltage Measurements or Jumping Terminals

N

YY

N

N

N

N

Y

Y

Y

Y

From previous page

Example of err or code shown on control display.

Page 8

SELECT Lockout R ESET

Status

Servic e Needed

Error Code Shown
in Water Heater Display

Troubleshooting

6

8

ACCESSING SERVICE MODE ON THE WATER HEATER DISPLAY (FOR SERVICE PERSONNEL ONLY)

The display has a “service mode” for changing the maximum setpoint and accessing information in aiding servicing of the
water heater. This procedure is for service and installation personnel only. To enter the Service Mode, follow the steps
illustrated below:

Step 1: Press “Select” and “Temperature Up” buttons together and hold for 3 seconds until “Max Setpoint” is shown in the
display.

Step 2: Pressing “Select” button will change display to next mode

SELECT SET

Status

°F

idl

e

Operational

W

ate

r

Temp

The following is the sequence of modes available in “Service Mode” by pressing the “Select” button:

Error Code Number (Display/Reset). This is only shown if there is an operating error in the “User Mode”.

"

Max Setpoint”

S

ELECT SET

Statu
s

idle

Operat ional

next to Temperature
Setpoint value.

M

ax

Setpo int

SELECT Lockout RESET

Status

Service N eeded

Error Code Shown
in Water Heater Display

Page 9

T

roubleshooting

Using Control Display for Servicing the

Water Heater

9

1. Max Setpoint (Display/Change)

2a. Water Temperature Average (Displays average if there are two sensors - sensor temperature displayed if single
sensor is used).

SELECT SET

Status

°F

idle

Water Temp

Operational

2b. Water Temperature - Upper Sensor (Displays if there is an upper sensor - some models)

SELECT SET

Status

°F

i

dl

e

O

perati onal

Upper Sensor

2c. Water Temperature - Lower Sensor (Displays if there are two sensors)

SELECT SET

Statu s

°F

idle

Operational

Lower Sensor

SELECT SET

Status

°F

idl

e

Operational

Max Setpoint value in
Water Heater Display

Max

S

etpoin

t

&

Page 10

T

roubleshooting

10

3. Flame Current of Pilot Flame Sensor (Displays only in the Heating Cycle)

SELECT SET

Status

Heating

Operational

Flame Current

ȝA

4. Setpoint (Display/Change)

SELECT SET

S

tatus

°F

i

dle

s

etpoint

Operational

5. °F/°C (Display/Change)

S

ELECT SET

Status

°

F/C°

idle

Operational

°

F

s

etpoint

6. Differential (Display only - shows the differential of the thermostat)

SELECT SET

Status

°F

idl

e

Differential

Operat ional

Page 11

T

roubleshooting

11

7. Software Version (Display only)

S

ELECT SET

Status

i

dle

Operational

Soft

8. Error Code History (Displays if there are present error codes or up to 10 previous error codes). Water Heater Display
will show a “--“ if there are no error codes.

S

ELECT SET

S

tatus

idle

O

perational

To change the Maximum Setpoint Limit (Max Setpoint) for the temperature setpoint:

Step 1: In service mode press the “Select” button until “Max Setpoint” is displayed.

SELECT SET

Status

°F

idle

Max

Opera tional

Setpoi nt

Page 12

T

roubleshooting

WARNING

Setting the water temperature
to the maximum set point can
result in scalding hot water
delivered to the faucets. It is
highly recommended that the
maximum setpoint be adjusted
to the lowest temperature
possible for the needs of the
installation. Make sure the
water heater control display is
not in a public area that can
result in the temperature
settings being improperly
adjusted.

12

Step 2: Press “Set” button to enter setting mode. “Max Setpoint” will flash to indicate setting mode.

SELECT SET

S

tatus

°

F

i

dle

O

perational

M

ax

Setpoint

Step 3: Press the “UP” or “DOWN” buttons to change the maximum setpoint value. This will limit the maximum setpoint
the user can select. Note: The maximum setpoint is approximately 180°F.

Step 4: Press “Set” button to confirm new “Max Setpoint” value and stop setting mode.

Page 13

"Max Setpoint" stops flashing

SELECT SET

Status

°F

idle

Ope

r

ational

Max

Setpoin

t

%

SELECT SET

Status

°F

idle

Operational

Max

Setpoint

%

"Max Setpoint" continues to flash

while making adjustments

T

roubleshooting

13

Step 5: 30 Seconds after the last button press, the Water Heater Display will go back to “User Mode”. It will read “Max
Setpoint” without showing a temperature value if the temperature setpoint is at the maximum setting. The Water
Heater Display can be set back to the “User Mode” immediately by pressing both the “Temperature Up” and “Select”
buttons together for 3 seconds.

SELECT SET

Status

idle

Operat ional

Max

Setpoi nt

%

&

Exiting Service Mode

Display of Water Temperature:

Step 1: In Service Mode, Press the “Select” button until “Water Temp” is displayed in the upper right section of the
water heater display. For water heaters using two temperature sensors in the tank, this will be the average reading
between the two sensors. For water heaters using a single sensor, this is the reading for the sensor.

Step 2: For water heaters using two temperature sensors, pressing the “Select” button again displays the Upper
Sensor temperature reading. “Upper Sensor” will be displayed in the lower right side of the status window of the
water heater display.

SELECT SET

Status

°F

idl

e

Operational

Upper Sensor

Page 14

T

roubleshooting

SELECT SET

Status

°F

idle

Operational

Water
Temp

&

14

Step 3: For water heaters using two temperature sensors, pressing the “Select” button again displays the Lower Sensor
temperature reading. “Lower Sensor” will be displayed in the lower left side of the status window of the water heater
display.

SELECT SET

S

tatus

°

F

idle

Operational

Lower Sensor

To Display Flame Sense Current of the Pilot Flame Sensor:

The pilot flame sense current is available only when the burners are in operation. Step 1: Make sure the status displays
“Heating” or draw enough hot water to start the burners. Step 2: Enter the “Service Mode” described previously. Step 3:
Press the “Select” button until a number value is displayed with “Flame Current” to the right of the number. The value
displayed is in microamps (ȝA).

S

ELECT SET

Status

Operational

Flame

C

urrent

Heating

ȝA

To Display and Change Temperature Setpoint:

Step 1: In “Service Mode” press the “Select” button until “Setpoint” is shown in the water heater display

SELECT SET

Status

°F

idle

setpoint

Operat ional

Page 15

T

roubleshooting

15

Step 2: Press the “Set” button to enter the setting mode. “Setpoint” will flash in the water heater display.

SELECT SET

Status

°

F

idle

s

etpoint

Operat ional

Step 3: To raise the temperature setpoint, press the “Temperature Up” button until the desired temperature is shown on
the water heater display.

S

ELECT SET

S

tatus

°F

idle

setpoint

Operat ional

%

Step 4: To lower the temperature setpoint, press the “Temperature Down” button until the desired temperature is shown
on the water heater display.

Page 16

SELEC

TSET

Status

°F

idle

setpoint

Operational

"Setpoint" Fl ashes

T

roubleshooting

WARNING

Setting the water temperature
to the maximum set point can
result in scalding hot water
delivered to the faucets. It is
highly recommended that the
maximum setpoint be adjusted
to the lowest temperature
possible for the needs of the
installation. Make sure the
water heater control display is
not in a public area that can
result in the temperature
settings being improperly
adjusted.

NOTICE

The maximum temperature that can be set in the Water Heater Display is limited to the “Max Setpoint” described

previously. To change the “Max Setpoint”, refer to the procedure “To Change the Maximum Setpoint Limit…"

described previously under “Accessing the Service Mode on the Water Heater Display”.

16

Step 5: When the desired setpoint is reached on the water heater display, press the “Set” button to confirm the new
setpoint. “Setpoint” stops flashing in the water heater display.

S

ELECT SET

S

tatus

°F

i

dle

setpoi nt

Operat ional

To Display and Change Temperature Format (°F/°C):

To Change Temperature Format in Display from °F to °C or °C to °F:

Step 1: While in “Service Mode”, press “Select” button until “°F/°C” is shown in the upper right portion of the water heater
display.

SELECT SET

S

tatus

idle

Operational

°F °F/C°

Step 2: Press “Set” button to change temperature format. “°F/°C” symbol will flash in the water heater display.

SELECT SET

Status

idle

Operational

°F °F/C°

Page 17

T

roubleshooting

17

Step 3a: Press “Temperature Up” button to change temperature format to °C

SELECT SET

Status

idle

Operational

°

C

%

°

F/C°

Step 3b: Press “Temperature Down” button to change temperature format to °F

SELECT SET

Status

idle

Operat ional

°F °F/C°

Step 4: Press “Set” button to confirm °F or °C format. °F/°C will stop flashing

SELECT SET

Status

°F

idle

Operational

°F °F/C°

Page 18

T

roubleshooting

18

Step 5: Pressing “Select” button will return display to setpoint in format selected (°F or °C) immediately

S

ELECT SET

Status

°F

idle

Operational

L

ower Sensor

Error Codes and Error History Display:

If there is an operating problem with the water heater, an error code number will appear on the water heater display with
“Service Needed” to the right of the “Status” indicator. The error code label is located under the water heater display.
The following section in this Service Manual explains the error codes with corrective actions to repair the water heater.

Example of Error Code in the Display

Error Code History:

In “Service Mode” pressing the “Select” button after the “Software Version” (item 8 in the previously described sequence
of service modes) will show an error code history, if there have been any previous operating problems with the water
heater. If the display shows --, there is not a current error code.
The Water Heater Display will provide up to 10 previous error codes. The oldest error code will be stored in code index
#1 and the most recent in code index #10.

Page 19

T

roubleshooting

SELECT

i

dle

S

ervice Need ed

Lockout R ESET

19

To view previous error codes:

Step 1:
In “Service Mode press the “Select” button until the next display after the “Software Version”. If there are no current
e

rror codes, the display will show -- .

SELECT SET

Status

°F

idle

Operational

Step 2:
Press the “Temperature Down” button to select the error code index, starting with the most recent error code “10”.

SELECT SE

T

Status

idle

Operation al

%

Step 3:
Press the “Select” button to view the error code for “code 10”. If there is a number displayed, note what the number is.
The label next to the water heater display will identify the code number. If no number is displayed with only a “--“ in the
water heater display, then there has not been an error code for error code index 10.

SELECT SET

Status

idle

Operational

Page 20

T

roubleshooting

20

Step 4:
Press the “Temperature Down” button to change to the previous code index, code #9.

SELECT SET

Status

idle

Operat ional

%

Step 5:
Press the “Select” button for code index #9 to view if there are any code numbers.

SELECT SET

S

tatus

idle

O

perat ional

Step 6:
Continue pressing the “Temperature Down” button to change to the next error code index and press “Select” to view the
error code number, if any, for that index number. Continue on to index #1, the oldest error code index. The water
heater display will store up to 10 error codes with the oldest code starting in code index #1 with the most recent code in
code index #10.

Step 7: 10 seconds after the last button press, the Water Heater Display will revert back to the current error code
display. To exit Service Mode, either wait 30 seconds or press Temperature Up button and Select Button for 3 seconds.

Page 21

T

roubleshooting

SELECT SET

Statu
s

°F

idl

e

setpoint

Oper ation al

&

%

Exiting Service Mode

21

ERROR CODE DEFINITIONS

If the water heater has an operating problem, there will be a number in the water heater display with
“Service Needed” shown below the error code number. Note the error code and the definition in the
chart below. This label appears on the control box under the water heater display. The following
sections will provide instructions for servicing each error code.

Page 22

T

roubleshooting

22

WARNING

The following procedure is for service and installation personnel only. Resetting lockout

conditions without correcting the malfunction can result in a hazardous condition.

If an error code is displayed (except for #4, low flame sense current), the water heater will be in a “lockout condition”
with the water heater display showing the error code number and “Service Needed” in the status section of the
display window. Error codes 62 (maximum number of retries detected) and 63 (maximum number if ignition
recycles detected) are “Soft Lockouts” in which the control can be reset in the “User Mode” by pressing the lower
r

ight button under “Lockout Reset” shown in the lower right portion of the display. The control will also go through 3

attempts to relight the burners every hour in the soft lockout condition.

All other error codes will put the water heater into a “Hard Lockout” condition, in which the water heater will not
operate and cannot be reset in the “User Mode”. To reset a hard lockout, first enter the “Service Mode” described
earlier by pressing both the “Temperature Up” and “Select Buttons” at the same time for 3 seconds. Then press the
lower right button under “Lockout Reset” in the water heater display and hold for 3 seconds.

L

ockout RESET

S

ELECT

Status

Servi ce needed

%

Error Code Shown in
Water Heater Display

Press for 2 seconds

Page 23

&

SELECT SET

Status

Servi ce Needed

%

SELECT Lockout RESET

Status

Servi ce Needed

Error Code Shown in
Water Heater Display

Step 1: Press for 3 seconds

to enter service mode.

Step 2: Press for 3 seconds to

reset control in service mode.

Resetting Error Codes in Hard Lockout Condition

23

SERVICE PROCEDURE D24-I

Thermostat Circuit Testing

CAUTION

Be Careful When Making Voltage

Measurements or Jumping Terminals

Not to Damage or Deform Connectors or

Connector Pins.

DANGER

120 volt exposure. To avoid personal injury,

use caution while performing this procedure.

WARNING!

Do not reset the display from the hard lockout

state without correcting the cause of the

overheating condition.

Check continuity of wi re harness to affected sensor. Measurement
of ohmeter should be close to 0 ohms. Replace wire harness if high
resistance is measured (over 0.5 ohms) Check wires for intermittent

c

onnections, shorts, frayed insulation. Replace if necessary

(see photo 8)

Turn power on to water heater.

Run water heater through heating cycle and verify proper operation.

Sensor temperature can be viewed when burner shuts off (see

section on viewing the disp lay in “Service Mode”.

This procedure assumes the flue damper is in working order. Be sure damper opens under its own power when the
thermostat circuit is by-passed. Damper must be open or removed during this test. Do not force damper open using your
hands or tools.

Turn power “OFF”.

Draw water to cool tank below 120 deg. F

Check lower sensor. Is the sensor fully inserted into the well?

Sensor is held in place with a clip fastened to the well (see photo 9)

Check lower sensor wire making sure it is not damaged or has

breaks in the wire ins ulatio n. Check upper harn ess wires to upper

sensor, if used (some models).

If sensor clip is damaged

replace clip. Replace lower

sensor if damaged.

Check Sensor Resistance

(see “Sensor Resistance

Testing” sect ion & photo 7)

Y

N

Page 24

Measuring upper
sensor resistance
through wire
h

arness

(

disconnected at

c

ontrol board).

Checking
continuity of
upper sensor wire
harness.

Removing lower
sensor from well.
Held in place by a
clip fastened to
well shoulder.

Condition: Water Heater Not Operating

Display shows error code “65”

High Water Temperature (over 200 deg. F)

If wire harness checks out O.K.check resistance of sensor. Refer to

section on Sensor Resistance Testing. If sensor resistance is not

near the values shown in the table, then replace upper or lower

sensor as indicated by error code number.

Unplug or disconnect electrical power to the water heater

Condition: Water Heater Not Operating

Display shows error code “31” (Upper Sensor

Readings Faulty) or error code “32” (Lower Sensor

Readings Faulty)

See next page

7

8

9

24

SERVICE PROCEDURE D24-I

Thermostat Circuit Testing

Condition: Water Heater Not Operating

Display shows error code “65”

High Water Temperature (over 200 deg. F)

Continued

WARNING!

Do not operate water heater without verifying that the overheating condition has been corrected.

Once cause of overheating condition has been diagnosed

and corrected, the control may be reset

Reconnect and switch on power to the water heater.
Enter service mode on the water heater display (see
illustration)
Press button under “Lockou t Reset” and hold for 3
seconds.
Set thermostat to the desired setting.
Water heater should start.
Monitor temperatures for on e comp lete heating cycle
making sure the maximum tank temperature remains well
below 200 deg. F

Page 25

25

°F012345678 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 1000 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 5446 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

In Degrees F

Sensor 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.

Page 26

SERVICE PROCEDURE D24-I

Thermostat Circuit Testing

Upper th ermister location

(applicable models)

Lower thermister

access located inside

control box.

Sensor Resistance Testing

Upper Sensor

1. Determine resistance value of upper sensor. Test across
grey wires.

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 Sensor:

1. Determine resistance value of lower sensor. Test across

center wire (common) to each outside wire. Resistance of both
thermisters in the lower sensor should be close to each other.
If the resistance values for both thermisters are not close to
each other, replace the lower sensor. The dual thermisters are
used to provide high limit protection in case the thermostat
circuit fails to shut off the water heater.

2. Draw quart of water off Drain Valve.

Using a thermometer, determine water temperature.

3. Use table below to verify correct resistance per water

temperature measured.

Are readings

correct?

N

Replace

thermister

Y

Check harness

continuity.

Continuity okay?

Y

Replace

control board

Replace
harness

N

CAUTION

Be Careful When Making Resistance

Measurements Not to Damage or

Deform Connectors or Connector Pins.

Conditions: Upper or Lower Sensor Reading
F

aulty, High Water Temperature, or suspect

thermostat is not accurate.

Checking resistance of

upper sensor

Checki ng resistance of

lower sensor (center and

outside pins)

10

11

26

SERVICE PROCEDURE D24-II

Pilot Operation Testing

CAUTION

Be Careful When Making Voltage

Measurements or Jumping Terminals

Not to Damage or Deform Connectors or

Connector Pins.

DANGER

120 volt exposure. To avoid personal injury,

use caution while performing this procedure.

Condition:

Pilot will not light or stay lit,

E

rror codes 62, or 63 shown on Water

Heater Display

Is there 22-27 volts AC output across

terminal pins 8 & 2 on “Control” plug

of Control Board? Carefully insert

meter probe in wire plug to check pin

terminals. Make sure control is in the

trial for ignition sequence (see

Sequence of Operation).

(see photo 13)

N

Y

Loosen pilot tubing connect ion at

the gas valve and soap test.

Is there pilot gas flow out of the
gas valve? See pilot illustration
for pilot inspection. (Wires must

be connected to gas valve during

this test).

Tighten pilot tube connection at
the gas valve. Check incoming
gas pressure to water heater. if

okay, replace gas valve

Check for clogged or kinked pilot

tube, clogged pilot orifice. Clean

or replace as needed.

(see “Pilot Burner Inspection”)

Is there 22-27 volts AC input across

wire leads

“MV/PV” & “PV” (yellow & red wires)

at Gas Valve?
(see photo 12)

Check wire har ness for damage or

loose connections. Repair or replace

as needed.

R

eset con trol by pressing the lower

r

ight button under “reset” on the

display for 3 seconds. Does control

board start ignition s equence and

start sparking (sparking noi se at p ilot

or at board)

Replace control boar d

12

Check across “MV/PV” & “PV” Wire

leads to gas valve

Y

Y

Y

N

N

Replace control board .

Is there spark at the pilot?

Check for:

Loose or damaged ignition wire

Grounded pilot electrode

D

amaged pilot.

Y

N

Checking for 24

volts output to

pilot valve

(yellow and red

wire pin
terminals) on
control board

“control” plug.

N

Turn on power to the water heater

and verify proper ope ration

Page 27

11

13

27

Condition:

Error code 57: Flame Rod Shorted

to Ground

Disconnect power. Shut off gas
supply to water heat er. Slide out
b

urner assembly (see section on

“

removing pilot and main burner

a

ssembly”).

SERVICE PROCEDURE D24-II

Pilot Inspection

Check to see if pilot shield is touching

pilot flame sensor or flame sensor

t

ouching pilot hood. Bend shield to

p

revent interference or replace pilot

s

hield.

Check pilot fl ame sense wire for

b

roken insulation. Replace pilot if

d

efective

Reinstall pilot and burner assembly.

Reconnect gas line union, turn on

g

as.

Make sure pilot shield
c

lears flame sense rod

Check for Gas Leaks

Page 28

Reconnect power and verify proper

ignitions.

Flame Sense Rod

Spark Electrode

28

SERVICE PROCEDURE D24-II

Pilot Operation Testing

CAUTION

Be Careful When Making Voltage

Measurements or Jumping Terminals

Not to Damage or Deform Connectors or

Connector Pins.

DANGER

120 volt exposure. To avoid personal injury,

use caution while performing this procedure.

C

ondition:

Pilot lights, no or low flame signal. Cont rol

Display shows “4” or “62” for Error Codes

(Servic e Needed). Control continues to spark

until system “Lock Out”.

Main burner will not light.

The microamp output of the pilot may be

checked by entering “Service Mode” on the

water heater display and press ing “Select”
until the flame current is shown. The control
must be in the heating mode with the pilot lit

to display a reading. See section on

accessing service mode on t he water heater

display.

Micro-amp readings

0.000 Micro Amp = Replace control board or pilot if wire is
damaged.

1.0 micro amp or less = Clean pilot flame rod or replace pilot.

C

heck for loose or damaged ground wire(s)

from gas valve to co ntrol board. Check

continuity of wires with ohmeter. Are ground

wires okay?

Check for loose or damaged flame sense

l

ead from pilot to Control Board. (see

illustration to the right). Is flame sense lead

okay?

R

epair wire lead

or replace pilot.

Repair ground

wire(s) or replace

as needed.

NOTE:

Check continuity of sense lead

to flame rod. If no continuity,

clean pilot flame rod or replace

pilot. Check pilot flame

appearance - if weak check for

clogged pi lot orifice, bent pi lot

tubing, or low inlet gas

pressure.

(see above illustration)

Y

Y

N

N

Check venting conditions or negative

pressure.

Is vent system okay?

Correct improper

venting condition.

Refer to Installation

Instructions

N

Is heater condensing causing pilot

interruption?

Make sure pilot shield is in place

and not bent or damaged (refer

to section on main burner and

pilot assembly) . Determine

cause for condensing and

correct.

(Possible under sized water

heater or high demand periods.)

Y

Y

N

Pilot flame sensor microamp output

shown in display using service mode.

Pilot must be lit to get reading.

Multi-meter set

to check

continuity.

Flame rod

Meter
Probe

Meter
Probe

Checking pilot flame senso r wire and flame

rod for con tinuity.

Page 29

H

eatin g

F

lame C urrent

ȝA

S

ELECT SE

T

Status

Operational

29

SERVICE PROCEDURE D24-III

Main Burner Operation Testing

CAUTION

Be Careful When Making Voltage

Measurements or Jumping Terminals

Not to Damage or Deform Connectors or

Connector Pins.

DANGER

120 volt exposure. To avoid personal injury,

use caution while performing this procedure.

Condition:

Main burner will not light,

Display shows “Heating” under temperature

setpoint.

Tank is cold.

I

s Pilot lit?

See “Pilot Will Not

Light”

Does control board continue to spark with

pilot lit?

See “Pilot Lights, No Flame

Signal”

Insert meter prob es int o back of

“Control” plug on control board to contact

pins for measuring voltage.

Is there 22-27 volts AC across

pin terminals 5 & 8? (Refer to wiring

diagram also see photo 14)

Disconnect brown wir e lead from

“MV” terminal of gas valve.

Is there 22-27 volts AC across

brown wire lead & ground?

(see photo 15)

Replace control board.

Be sure contr ol display is showing “Heating”,

pilot is lit and control is not sparking.

Recheck voltage across control board

pin terminals 5 & 8 (MV & MV/PV)

Is voltage present?

Check wire harness for damage or loose

connections. Repair or replace as needed.

Check incoming gas pressure
to gas valve and manifold
pressure to burners (See next
page for procedure for
checking manifold pressure). If
inlet gas pressure is O.K.,
replace gas va lve. (See photo
on next page for gas valve
inlet pressure tap )

N

Y

N

N

Y

N

Y

Y

N

Y

C

hecking MV &

M

V/PV control plug

pins to gas valve

for 24 volts output

during heatin g

cycle (pilot must be

lit with no

sparking).

Brown wire disconnected

from “MV” terminal of gas

valve

Ground lug of

gas valve

Checking main valve (MV) voltage to gas valve.

Page 30

15

11

14

30

SERVICE PROCEDURE D24-III

Main Burner Operation Testing

CAUTION

Be Careful When Making Voltage

Measurements or Jumping Terminals

Not to Damage or Deform Connectors or

Connector Pins.

DANGER

120 volt exposure. To avoid personal injury,

use caution while performing this procedure.

Condition:

Main burner short cycles.

Control Display may show error

c

ode “63, 57, or 4” and be in

“

Soft Lockout” stat e.

C

heck gas inlet pressure to the wat er

heater gas valve.

Line pressure should be:

Nat. = Min. 5.5" W.C.: Max. 14.0" W.C.

LP = Min. 11.0" W.C.; Max. 14.0" W.C.

Is gas pressure within proper

specification? (see photo below)

Determine caus e of incorrect gas

pressure and correct. Contact

your gas supplier.

Check venting conditions, clogged vent,

down draf ts or negative building

pressure

Is vent system okay?

Correct improper vent ing

condition. Refer to

Installation Instructions

N

Is there sufficient combustion air being

supplied to the water heater? Are there

combustion air openings or supply pipes

to the room? Open access door to the

utility room to see if problem is

corrected.

Provide proper

combustion air to water

heater. Refer to

Installation Instructions

N

Check burner tubes for s cale or debris

build-up. Clean burner as necessary.

(see Main Burner and Pilot Removal and

Inspection)

Check tank flues for blockage or debris

build-up causin g restriction.

(see Flue Baffle Removal, Inspection)

Check for unstable pilot flame or

oxidation of the flame rod on pilot

causing weak pilo t signal. Make sure

pilot shield is in place and does not

touch pilot flame sensor.

(See Pilot Inspection section)

Line gas

pressure port

Manifold Pressure Port with hose

barb inserted for measuring

pressure

N

Y

Y

Page 31

Check manifold pressure. See photo on lower right section of page for
manifold pressure tap location. Refer to water heater rating la bel for
specified manifold pressure. If the manifold pressure is not within 0.3"
w

.c. of the specified pressure, then remove the regulator cap from the
gas valve and turn plastic screw clockwise to increase pressure and
counterclockwise to decrease pressure . Be sure inlet gas pressure is at
least 1" w.c. above the manifold pressure. Replace regulator screw and
pressure tap cap when finished. Is manifold pressure O.K.?

Gas Valve pressure

regulator cap (adjustment

screw accessible by

removing cap scre w)

16

Replace Gas Valve.

N

Y

Y

Connect hose barb to manifold

pressure port shown above, then

connect monometer to measure

gas manifold pressure.

31

SERVICE PROCEDURE D24-IV

M

ain Burner & Pilot

Removal and Inspection

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Main Burner Removal

Step 1. Disconnect (un-plug) water heater from

electrical 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 flame sense wire & orange ignition

wire from Control Board (see photo 18).

Step 7. Remove the two burner rack mounting screws (see photo 17).

Step 8. Slide complete burner rack out from heater

(see photo 19).

Step 9. To install burner, reverse above procedure.

Step 10. Check for gas leaks and verify proper operation.

G

as Valve

Control Knob

Gas Sup ply

Line

G

as Valve

Wire Leads

B

urner Rack
Mounting

Screw

Main Burner Inspection

Step 1. Burner tubes should be free of any flue

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 flame. Pilot should be
mounted using the two mounting screws through
the burner support bracket resulting in a level
pilot position.

19

Pilot

Shield

17

20

Pilot spark wire

(Orange)

Pilot Flame Sense

Wire (White)

Page 32

18

32

SERVICE PROCEDURE D24-IV

M

ain Burner & Pilot

Removal and Inspection

Pilot Burner Removal

Step 1. With burner rack removed from heater, disconnect

pilot tube connection from gas valve

S

tep 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 Shield

Pilot & Pilot Sh ield

M

ounting Screws

Ground Wire

L

ocation

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 flame sense wire. If found,

pilot must be replaced.

c) Oxidation build-up on flame rod. Clean flame rod

or replace pilot as necessary.

Step 2. Inspect pilot orifice:

a) Remove 7/16" ferrule nut from bottom of pilot.

b) Remove pilot tube and orifice from pilot.

c) Inspect pilot tube for blockage. Clean or replace

as necessary.

d) Inspect pilot orifice for blockage. Clean or replace

as necessary.

Flame Sense

Wire

Ignition

Wire

Ceramic

Insulators

Flame

Rod

Pilot

Orifice

7//16"
ferrule

Nut

Aluminum

Pilot Tubing

Page 33

21

22

33

SERVICE PROCEDURE D24-IV

Control Board Replacement

Control board replacement

S

tep 1: Disconnect Power

Depress
plastic
t

abs

Slots in
control panel

Unhook tabs
from control
panel slots

To remove lower sensor

Remove clip, pull sensor out.

S

tep 2: Unplug wire connections from board.

Pull out sensor

Remove clip

Wire connections

DANGER

120 volt exposure. To avoid personal injury,

unplug while performing this procedure.

Page 34

23

25

24

26

Step 3: To remove board, tilt control panel to the right
and slide control hook tabs from slots in control panel.

IMPORTANT

When replacing lower sensor, make sure

sensor is fully inserted into the well and

securely held by the clip on the well groove.

(see photo 25)

34

SERVICE PROCEDURE D24-V

Flue Baffle Removal, Inspection

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 flue damper from wire harness and remove

flue damper from top of water heater (see photo 27).

Step 4. If required, turn “OFF” water supply & 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. Note, it may
be necessary to use a screw driver to pry underneath
jacket head (see photo 28).

Step 6. Remove insulation from top of water heater to expose

collector cover.

Step 7. Remove screws from side (or top) of collector cover. Note, it may be

necessary to chisel away some foam to access screws (see photo 29).

Step 8. Remove collector cover from water heater by using

pipe wrench as illustrated in photo 30.

Step 9. Remove flue baffles from water heater. Note, it may be necessary

to use pliers to loosen and remove baffles from flue tubes (see photo 31).

Step 10. Visually inspect flue baffles. Flue baffles may show signs

of oxidation; this is normal. If the oxidation has deteriorated
any portion of the flue baffle, replacement is recommended.
If any restrictors are missing, replacement is recommended.

Step 11. Upon completion of inspection or subsequent replacement,

reinstall flue baffles into heater.

Step 12. Reinstall collector cover and insulation over collector cover.

Step 13. Reinstall jacket head, flue damper and draft diverter. Reconnect venting.

Step 14. Reconnect plumbing connection to top of water heater

& turn on water supply if required.

Step 15. Check for leaks and verify proper operation.

WARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Page 35

28

27

29

30

Flue Baffle

31

35

SERVICE PROCEDURE D24-VI

Anode Removal and Inspection

Step 1. Disconnect (unplug) water heater from electrical supply.

Step 2. Turn “OFF” water supply to water heater.

Step 3. Open a near by 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 a minimum of 5 gallons 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 flue damper from wire harness and remove flue damper from top

of water heater (see photo 32).

Step 7. If required, turn off water supply and 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. Note, it may
be necessary to use a screw driver to pry underneath
jacket head (see photo 33).

Step 9. Remove insulation from top of water heater to expose collector cover,

remove if necessary. (see next page for approx. anode locations)

Step 10. Remove screws from side (or top) of collector cover. Note, it may be

necessary to chisel away some foam to access screws (see photo 34).

Step 11. Locate and remove anode rods from top of water heater (1-1/16 hex socket).

Note, anodes located outside of the collector (see photo 35) may require foam
to be chiseled away to access anode rods. (see next page for approx. anode locations)

Step 12. Visually inspect anode rod. Anode rod may show signs of depletion;

this is normal. If the anode shows signs of depletion
(approximately 5/8", see photo 36), replacement is recommended. If any of
the steel core of the anode is exposed, replacement is recommended.

Step 13. Upon completion of inspection or subsequent replacement,

reinstall anode rods into water heater.

Step 14. Check for leaks.

Step 15. Reinstall collector cover & insulation over collector cover.

Step 16. Reinstall jacket head, flue damper and draft diverter. Reconnect venting.

Step 17. Reconnect plumbing connection to top of water heater if required.

Step 18. Restore water supply and power to water heater.

Step 19. Verify proper operation.

W

ARNING

Heater components may be HOT when performing the following steps in this procedure.

Take necessary precaution to prevent personal injury.

Page 36

33

32

34

35

Anode

36

Replace Anode

36

Page 37

SERVICE PROCEDURE D24-VI

Anode Removal and Inspection

Approximate Anode Rod Locations

37

G

eneric Parts List

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 Baffle

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. Thermostat Sensor Clip

20. Burner Assembly Complete

21. Brass Drain Valve

22. Cold Water Inlet Nipple (side)

23. Thermostat Well

24. Damper Harness

25. Lower Thermostat Sensor

26. Control Box Assembly Complete

27. Hot Water Outlet Nipple (side)

28. Upper Thermostat

29. Utility Cover

30. ASSE Approved Mixing Valve

31. Pipe Plug ¾ NPT

Page 38

2

3

5

4

30

6

28

29

27

19

23

26

25

22

21

20

15

15A

16/16A

17/17A

18

14

13

12

10

11

1

9

2

4

8

7

38

G

eneric Parts List

1A. Draft Panel
2A. Burner Rack
3A. Burner Tube
4A. Gas Valve
5A. Burner Manifold
6A. Main Burner Orifice
7A. Pilot Shield
8A. Pilot Burner
9A. Pilot Orifice
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. Ground Wire

Page 39

20

A14A15A

5A

13A

16A

4A

3A

6A

11A

12

A

9A

10A

8A

7A

2A

1

A

19

A

18A

17

A

39

G

eneric Parts List

1B. Temperature Display
2B. Control Box Cover
3B. Integrated Control Board
4B. Screw 8-16 X ½ PHCR
5B. Transformer
6B. Ground Lug
7B. On/Off Switch
8B. Control Box Panel
9B. Screw 8/32 X ¼ PHCR
10B. 7/8" Snap Bushing

11B. Power Cord Strain Relief
12B. Pilot Wire Strain Relief
13B. Secondary Transformer Wiring Harness
14B. Primary Transformer Wiring Harness
15B. Screw 8-18 x ¾ PHCR
16B. Gas Valve Control Wiring Harness
17B. Damper Wiring Harness
18B. Power Cord
19B. Display Control Wiring Harness
20B. Display Cover Wiring Harness

Page 40

15B

1B

3B

4

B

5B

6

B

7B

8B

9B

13B

14B

1

7B

1

8B

16B

2B

19B

2

0B

11B

10B

12B

40

NOTES

AC Alternating Current
BTU/H British Thermal Units per Hour
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
ȝA Micro Amp

Page 41

G

lossary of Terms

41

NOTES

NOTES

Email

[e-mail]

[e-mail]

www.bradfordwhite.com