A.O. Smith BTH 120 Building instructions

Part No. TC-044R2
$15.00 Printed in the U.S.A. 3 00
This Service Handbook was prepared by:
The Training Department
Irving, Texas
BTH 120, 150, 199, 250
Service Handbook
Includes Parts List For
Series 960 through 967

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
1
BTH HANDBOOK
TABLE OF CONTENTS
PAGE
Introduction. .................................. 2
Installation
Clearances.................................. 3-4
Air Requirements ........................ 5-9
Contaminated Air ........................ 10
Flammable .................................. 10
Condensation .............................. 11
Venting ........................................ 12
Sequence of Operation
Mechanical .................................. 13
Information
Multiple Unit Piping...................... 14
Controls ...................................... 15-17
Troubleshooting
Pre-Service ................................. 18
Igniter Continuity Check ............... 18-19
Control Board Check ................... 20
Transformer ................................. 21-22
Control Board .............................. 22-23
Temperature ................................ 24
Blower ......................................... 25-26
PAGE
Troubleshooting - continued
Pressure Switch Continuity .......... 27-28
Voltage Test - Igniter .................... 29
250 Blower Test........................... 29
Gas Pressure Test ....................... 30
Tables
Component Part .......................... 31
Orifice Tables .............................. 31
Pressure Switches ...................... 32
Wiring Schematics
Natural and Propane Gas ............ 33
Service Aids. ................................. 34
General Questions & Answers..... 35
Error Codes................................... 36
Service Checklist .......................... 37
Parts Lists
966 & 967 Series ........................ 38-49
960 Series .................................. 50-53
962 Series .................................. 54-61

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
2
BTH HANDBOOK INTRODUCTION
This service handbook is designed to aid in servicing and troubleshooting A. O. Smith BTH water
heaters in the field. No duplication or reproduction of this book may be made without the express
written authorization of the A. O. Smith Water Products Company.
The following text and illustrations will provide you with a step by step procedure to verify proper
installation, operation and troubleshooting procedures. Additional quick reference data is included to
assist you in servicing this product.
The information contained in this handbook is designed to answer commonly faced situations encoun-
tered in the operation of the BTH product line and is not meant to be all inclusive. If you are
experiencing a problem not covered in this handbook, please contact the A. O. Smith Technical
Information Department at 1-800-527-1953 or your local A. O. Smith Water Products company
representative for further assistance. This handbook is intended for use by licensed plumbing
professionals and reference should be made to the instruction manual accompanying the product.
This handbook contains supplemental information to the BTH instruction manual.
Qualifications: Installation or service of this water heater requires ability equivalent to that of a
licensed tradesman in the field involved. Plumbing, venting, gas supply and electrical testing skills are
required.
Tools Required:
• Phillips head screw driver
• Flat tip screw drivers
• Set of marked drill bits
• Electric multimeter tester
• Gas pressure gauge or manometer (gauge - AOS part number 8099-2)
• Water pressure gauge (AOS part number 4798)
• Draft gauge
• Thermometer (AOS part number 4870 - range 0 thru 220°F)
• 1/2 inch socket with extension for removal of the cleanout
• 1 1/8 inch socket for removal of the anode
• 1 inch socket for hot surface igniter removal
• Pipe wrench for union disconnect
*Note: Also, have a copy of the instruction manual for the model and series BTH
that you are servicing.
Revision 2 includes an added Multiple Venting statement on page 3 and a new Blower Motor Ohms
Resistance Table on page 25. The Pressure Switch Table on page 32 was expanded/revised.

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
3
Installation: This portion of the handbook will review often overlooked installation considerations, taking note
of necessary instruction requirements for the
BTH 120 - 250 / 966 and 967 Series. The instal-
lation manual covers most of these items in de-
tail. BTH heaters are approved for installation on
combustible flooring. Most can be installed in an
alcove with minimum clearances to combustibles
or non-combustibles of 0 inches from the sides
and rear, 0 inches from vent piping, and 1.5 inches
from the top cover. A 24 inch clearance for all
serviceable parts is recommended. Clearances
may vary between BTH models. See instruction
manual or the label on the heater for clearances
applicable to your specific model.
This illustrates the exterior clearances for these BTH units when installed as direct vent heaters.
BTH Model 120
BTH Model 150-199
BTH Model 250
Note: 24 inches between inlet and outlet is a minimum. Greater distance is
recommended. In colder climates increasing the 24" minimum to a maximum
practical distance, will reduce the possibility of frost over from side winds blow-
ing exhaust vapors to the air intake of the direct vent.

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
4
EXTERIOR CLEARANCES
Horizontal Vent (using room air for combustion)
EXTERIOR CLEARANCES
Direct Vent
CAUTION
DO NOT TERMINATE THE VENTING WHERE NOISE FROM THE EXHAUST OF INTAKE WILL BE OBJECTIONABLE.
THIS INCLUDES LOCATIONS CLOSE TO OR ACROSS FROM WINDOWS AND DOORS. AVOID ANCHORING THE
VENT AND INTAKE PIPES DIRECTLY TO FRAMED WALLS, FLOORS OR CEILINGS UNLESS RUBBER ISOLATION
PIPE HANGERS ARE USED. THIS PREVENTS ANY VIBRATIONS FROM BEING TRANSMITTED INTO THE LIVING
SPACES.
When multiple units are direct vented through a wall, all intake vent terminals must be no lower than the
highest exhaust vent terminal.
Regulator
Gas
Meter
3' Min.
3' Above Any Forced
Air Intake Within 10'
4' Minimum
4' Minimum
4' Minimum
Exhaust
3' Minimum
From
Inside Corner
Recommended
Vent Hood Must Be
Mounted 4' Minimum
Below Doors and Windows
Vent Hood Must Be
Mounted 4' Minimum
Below Windows
1' Above
Grade*
Vent Hood Must Be
Mounted 1' Minimum
Below Windows
*Recommended Clearance of 1' Above "Anticipated Snow Level" Where Applicable
Exhaust
Exhaust
Exhaust
Warning-
Vent Hood(s) May Be
Extremely Hot During
Operation
Regulator
Gas
Meter
3' Min.
1' Above
Grade*
3' Above Any Forced
Air Intake Within 10'
Vent Hood Must Be
Mounted 1' Away
Horizontally From Doors
and Windows
Vent Hood Must Be
Mounted 9" Minimum
Above Doors
and Windows
3' Minimum From
Inside Corner
Recommended
*Recommended Clearance of 1' Above "Anticipated Snow Level" Where Applicable
Exhaust
Exhaust
Exhaust
Exhaust
Intake
Intake
Intake
Intake
Air
intake
(optional)
Intake Air Must Be
Mounted 1' Minimum
Below Windows
Exhaust 4"
Minimum
Warning-
Vent Hood(s) May Be
Extremely Hot During
Operation

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
5
MINIMUM AIR FOR COMBUSTION
10 CUBIC FEET OF AIR PER 1,000 BTU
Stoichiometric or theoretical complete combustion requires 10 cubic feet of air per 1000 BTUH input of the gas
input. The National Fuel Gas Code also recommends an additional 2.5 cu.ft. of "excess air". This
12.5 cu.ft. minimum supply air per 100 BTUH input applies to natural and propane gas models.
The National Fuel Code also specifies minimum make-up air opening sizes for various building installations.
(Ref: NFPA 54, ANSI Z223.1, sec 5.3).
MAKE-UP AIR
DIRECT VENT INSTALLATION
This model is approved for direct venting either horizontally or vertically or conventional venting horizontal or
vertical. Direct venting avoids using room air for combustion and eliminates the need for additional air
intake ducts. The direct vent installation may have up to 50 equivalent feet of exhaust and 50 equivalent feet
of air intake piping
1,000
BTU
10 CU.
FT.
COMB.
AIR
2.5 CU. FT.
EXCESS
AIR
+

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
6
MAKE-UP AIR
DIRECT COMMUNICATION
A fresh supply of make-up air for combustion can be supplied to the heater through make-up air ducts, which
directly communicate with the out of doors. Two openings are required - one within 12 inches of the top of the
enclosure and one within 12 inches of the bottom of the enclosure. Each opening shall have a free area of not
less than 1 square inch per 4000 BTUH of the total input of all appliances within the enclosure.
The lower opening is primarily providing combustion air. The upper opening is providing vent dilution air and
acts as a relief opening for flue gases should the vent become obstructed or a down draft condition occur.
Additionally, when the heater is installed in a confined space and communicating with the outdoor air, one
permanent opening, commencing within 12 inches (30 cm.) of the top of the enclosure, shall be permitted
where the equipment has clearances of at least 1 inch (2.5 cm.) from the sides and back and
6 inches (16 cm.) from the front of the appliance. The opening shall directly communicate with the outdoors
and shall communicate through a vertical or horizontal duct to the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors, and shall have a minimum free area of:
a. 1 sq. in. per 3000 BTU per hr (7 cm2 per kW) of the total input of all equipment located in the
enclosure, and
b. Not less then the sum of the areas of all vent connectors in the confined space.

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
7
MAKE-UP AIR
VERTICAL DUCTS
Often it is more practical to install vertical make-up air ducts to the out doors. Again, two openings are required
- within 12 inches (30 cm.) of the top of the enclosure and one within 12 inches (30 cm.) of the bottom of the
enclosure. Each opening shall have a free area of not less than 1 square inch per 4000 BTUH of the total input
of all appliances within the enclosure.

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
8
MAKE-UP AIR
HORIZONTAL DUCTS
When the heater is installed in an interior room with no roof access for vertical ducts, horizontal make-up
ducts should be installed. When using horizontal ducts, two openings are required - within
12 inches (30 cm.) of the top of the enclosure and one within 12 inches (30 cm.) of the bottom of the enclo-
sure. Each opening shall have a free area of not less than 1 square inch per 2000 BTUH of the total input of all
appliances within the enclosure.
Fresh AirFresh Air
Fresh AirFresh Air
Fresh Air
Fresh AirFresh Air
Fresh AirFresh Air
Fresh Air

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
9
INSUFFICIENT MAKE-UP AIR
BACKDRAFT
Insufficient make-up air is a major cause of combustion problems. One common example is in a restaurant
installation where exhaust vent equipment was not considered in sizing make-up air requirements. This may
result in air being backdrafted by the restaurant exhaust equipment through the heater causing flue gas spill-
age, flame roll out, improper combustion, inconsistent pilot operation, and/or erratic heater shutdown.
A possible solution to this situation would be to use a BTH with direct venting.
A less common service issue associated with a backdraft or negative pressure room would be the opening or
closing of air pressure switches. This may result in erratic or no heater operation.

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
10
CONTAMINATED AIR
Along with adequate make-up air, the quality of the air is important. Contaminants in combustion air can lead
to premature heater failure. Vapors from bleaches, soaps, salts, etc. are drawn into the combustion chamber
with the make up air and, once fired, mix with water vapor in the gasses to form extremely corrosive hydrochlo-
ric or hydrofluoric acid an other corrosive byproducts. Dust drawn in may build up on the blower or clog the
main burner ports. Also, be certain to examine the exterior area around the air intake of a direct vent installa-
tion for these contaminants.
AIR FOR COMBUSTION
FLAMMABLE ITEMS
Flammable items or pressurized containers or any other potentially hazardous articles must never be placed
on or adjacent to the heater. Open containers of flammable material should not be stored or used in the same
room with the heater or in the area of the exterior air intake of a direct vent installation. Direct venting does not
eliminate the need to remove flammable or corrosives from the area surrounding the heater.
= RUST
CHIPS

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
11
The extra high thermal efficiency of the BTH will result in condensation in the flue passage. The following
answers common questions about this condensation.
Can I drain this condensation to the floor drain? The "Corrosion Resistance of Cast Iron Soil Pipe" by the
Ductile Metals Association (formally the Cast Iron Soil Pipe Institute) states that:
"Internal corrosion of cast iron soil pipe and fittings can be caused by strong acids or other reagents having
an acidity of pH 4.3 or less if allowed to contact cast iron pipe for an extended period of time without sufficient
dilution to raise the pH valve about 4.3. By avoiding low pH discharges, internal corrosion problems can be
limited or eliminated, assuring the owner many years of service."
WHAT ABOUT THE Ph VALUES OF CONDENSATE AND SODA POP?
The pH of the BTH condensate average 4.5 which is approximately 4 times less concentrated than the limit
of 4.3 recommended by the DMA. Any water flow in the drain rapidly dilutes the condensate even more. A can
of leading carbonated cola drink measured a pH of 2.5 which is 300 times more condentrated than the BTH
condensate.
WHAT DOES THE Ph SCALE MEAN? The PH value is a measure of acidity or alkalinity. A pH of 7 is neutral.
Numbers from 7 to 1 indicate increasing acidity and numbers from 7 to 14 indicate increasing alkalinity. The
pH scale is similar to the Richter scale used to measure earthquakes. Each number indicates a change of 10
times the concentration of the previous value. A pH-6 is 10 times more concentrated than a pH-7, a pH-5 is
(10x10) 100 times pH-7 and pH-4 is (10x10x10) 1,000 times pH-7, etc.
WHAT ABOUT CONDENSATE NEUTRALIZERS? Condensate neutralizers are usually not necessary. A
condensate neutralizer is easy to make by filling a short length of 2" or 3" PVC pipe with landscape marble
chips, capping it and installing it in series with the condensate drain of the equipment. Most commercial
neutralizers are off the market because of poor demand for the product. Condensation from the exhaust vent
piping and tank internal flue way must be allowed to drain. A "blocked flue" indication will often be your first
indication that condensate is not draining.
CONDENSATE
DRAIN HOSE
MUST DRAIN.
The average dewpoint of natural gas flue products is 127 °F. Propane flue
products is 119° F. With 70° F ambient air temperature and 180° F stored
water temperature, exhaust gas will be approximately 140° F. Recommended
safe water storage temperature is 120° F.
CONDENSATION
NOTE: This unit can be vented using only PVC (Class 160, ASTM D-
2241; Schedule 40, ASTM D-1785; or Cellular Core Schedule 40
DWV, ASTM F-891), Schedule 40 CPVC (ASTM F-411), or ABS
(ASTM D-2661) pipe. The fittings, other than the TERMINATIONS
should be equivalent to PVC-DWV fittings meeting ASTM D-2665
(Use CPVC fittings, ASTM F-438 for CPVC pipe and ABS fittings,
ASTM D-2661/3311 for ABS pipe. If CPVC or ABS pipe and fittings
are used, then the proper cement must be used for all joints, including
joining the pipe to the Termination Tee (PVC Material). PVC Materials
should use ASTM D-2564 Grade Cement; CPVC Materials should
use ASTM F-493 Grade Cement and; ABS Materials should use
ASTM D-2235 Grade Cement.
NOTE: for Water heaters in locations with high ambient temperatures
(above 100°F) and/or insufficient dilution air, it is recommended that
CPVC or ABS pipe and fittings (MUST USE SUPPLIED VENT
TERMINAL) be used.

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
12
VENTING
Equivalent Feet of Pipe Intake or Exhaust
MANIFOLD GAS
SUPPLY GAS
Gas Type
Minimum
Inches
W.C.
Maximum
Inches
W.C.
Natural 5 10.5
Propane 11 13.8
NOTE: Pressure without capacity will result in
lockout. Follow the piping guidelines in the
instruction manual.
The supply gas pressure in normally measured
at the dirt leg or at the inlet gas pressure tapping
on the gas valve. This reading must be measured
with 'flowing' gas.
Regulated Gas Supply
Line
Main Gas Shutoff Valve
Dirt Leg Tee
The manifold gas pressure is measured at the
manifold pressure tap of the gas valve when the
gas is flowing.
The gas valves used on all BTH water heaters are
24 volt AC combination step opening gas valves.
They incorporate the main valve, and gas pressure
regulators into one body.
Pipe Cap
Pressure Regulator Adjustment
(Cover Screw)
Inlet Pressure Tap
Gas Inlet
Gas Valve On/Off
TH & TR Terminals
(Main Valve)
Manifold
Pressure Tap
Gas Outlet
Gas Type
Minimum/Maximum
Inches W.C.150/199
Minimum/Maximum
Inches W.C. 120/250
Natural 3.5 4.0
Propane 10 10.0
Number of
90° Elbows
3" Minimum
Pi
p
e
(
Feet
)
3"
Maximum
Pi
p
e
(
Feet
)
4"
Maximum
Pipe
(
Feet
)
One (1) 7 45 115
Two (2) 7 40 110
Three (3) 7 35 105
Four (4) 7 30 100
Five (5) 7 95
Six
(
6
)
790
VENT LENGTH TABLE
4-inch PVC may be used for a MAXIMUM intake of ONE HUNDRED TWENTY (120) EQUIVALENT FEET
and a MAXIMUM exhaust of ONE HUNDRED TWENTY (120) EQUIVALENT FEET. The maximum number
of 90°elbows with the 4-inch venting is six (6) on the intake and six (6) on the exhaust. A 90°elbow is equal
to five (5) equivalent feet of pipe. One (1) 90°elbow is equal to two (2) 45°elbows. Any venting configuration
using less than 50 equivalent feet should use 3-inch venting. See Vent Length Table.
The 3-inch venting terminals (provided) must be used with the 4-inch venting by adding 4 x 3 reducing
couplings at the venting terminals. A reducing coupling is also needed immediately after the condensate
elbow (exhaust) and immediately before the 3-inch blower adapter (intake) if direct venting is installed. See
Vent Length Table.
--
--

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
13
Note: If the lower temperature probe is defective or unplugged, display will show upper tank
temperature. Heater may fire but stack.
If upper high limit/tank temp. thermistor is defective or disconnected, cycling power off then on
displays will be: 00, 120, 12, water temp at lower probe, flashing "04" code.
BTH Sequence of Operation
Gas Valve Opens
Power Off
Power On
Call for heat (Temp.
setting less diff.)
Blower Prepurge
20 Seconds
HSI is Energized
Blower speed
reduces BTH 250
only
Igniter
warm-up period
Blower to Full RPM
BTH-250 only
7.5 Sec Trial
for ignition
Blower Prover
Closes at .45"
Positive Press
BTH 120 and 250
Only
Low Supply Gas
Pressure
Switch NC 4.3"
w.c. gas
press. to close
If ECO is closed low
gas pressure switch
is closed
(120 & 250
models only)
Blocked Outlet-NC
Opens at 2.5"
Positive Press
NO
Flame Rod Does
Not Prove Flame
30 Second
Purge
Retry-Max
3 times
YES
Flame Rod Senses
Flame .7 microamp
minimum
Gas Valve Closes
30 Sec Post Purge
Tank Water Heated
to Set Point
If reset is pushed
and released while
this is displayed, the
board will do an
operational self
check.
Pushing the reset at
this time will display
tank temp. setting.
Push once and hold
to increase setting.
Push twice and hold
to decrease settings
110°-180°
Display "00"
Supply Volts
"120"
Weighted Average
Tank Termpature
Bottom vs Top
Draft Prover
Switches to
Proper State
Blocked Inlet-NC
Opens .75" wc
Neg. Press
Temperature
Offset 12%
Display Sequence
Pressure Switch Information
Display Failure Code

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
14
NOTES APPLY TO ALL SYSTEMS:
*ADD GATE VALVES TO INLET AND OUTLET OF EACH UNIT
FOR ISOLATION FLEXIBILITY. LOCATE AT THE SAME POINT
FROM TEE.
** ADD THERMAL EXPANSION TANK TO COLD WATER
SUPPLY IF NECESSARY.
CONDENSATION HOSE MUST BE ALLOWED TO DRAIN.
NOTE: T&P VALVES MUST BE PIPED TO OPEN DRAIN OR
PER LOCAL CODE.
MULTIPLE UNIT - WATER PIPING
REVERSE RETURN PIPING
WITH TANK
2"
HOT TO FIXTURES
VENT TO
OUTDOORS
2"
T&P
EXHAUST
RETURN
CHECK
VALVE
T&P VALVE
2"
COLD
SUPPLY
TANK
THERMOMETER
CIRCULATOR THERMOSTAT
SET 5° COOLER THAN
HEATER SETTINGS
HOT
2"
COLD
RETURN
COLD
RETURN 1 1/2"
1 1/2"
1 1/2"
PIPE TO OPEN
DRAIN
1 1/2"
2"
1 1/2"
REVERSE RETURN PIPING
PARALLEL PIPING WITH TANK
PUMP
CHECK
VALVE
PUMP
PARALLEL PIPING

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
15
CYCLONE BTH
NORMAL INDICATIONS / READINGS
DURING CALL FOR HEAT
Tank temperature below control setting
(to check control setting, press reset button)
•On/off switch “on”
Note: Power must be on at least 4 seconds before reset can be pressed to indicate control set-
ting.
• Control panel indication lights “on”
•On/off switch light “on”
•120 VAC
•24 VAC
•High limit
•Blower fan (while fan is running)
•Pressure switch (while blower is running)
•Control status
•Thermostat “on”
•Gas valve (during 4 second trial for ignition and while
burner is on)
•Current average tank water temperature displayed
DISPLAY PANEL (CONTROL PANEL)

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
16
120 VAC present to ground and:
•Each black terminal of on/off switch
•CN1 black term 1
•CN 2 black term 1
•CN 4 black term 1
•CN 5 white term 1 (only while ignitor is heating)
Note: CN 6 black term 2 will give reading of 90-100 volts – ignore
this reading.
24 VAC present to ground and:
•CN 3 red term 1 and red term 4
•CN 4 blue term 4
•CN 6 blue term 3, brown term 4, and brown term 6
•Each terminal of the 3 or 4 pressure switches
CYCLONE BTH
NORMAL INDICATIONS / READINGS

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
17
NORMAL INDICATIONS / READINGS
AFTER TANK IS SATISFIED
Tank temperature above control setting
•On/off switch is “on”
Normal conditions will be 120 volts present to ground and:
•Each black terminal of on/off switch
•CN 1 black term 1
•CN 4 black term 1
Note: CN 6 black term 2 (flame sensor) may display 90-100 VAC – this is a non-reading, ignore it
24 VAC present to ground and:
•CN 3 red term 1 and red term 4
•CN 4 blue term 4
•CN 6 brown term 4
•Blocked inlet switch –each terminal (tube connects to inlet of blower)
•Blower prover switch –upper terminal (this is the jumper wire from the blocked inlet switch)
Control panel indication light “on”
•On/off switch light
•120 VAC
•24 VAC
•High limit
•Control status
•Current (average) tank temperature will be displayed
(BTH 120, 250 Only)

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000© Training Department
18
TROUBLESHOOTING
PRE-SERVICE TIPS
CONTINUITY CHECKS
After 20 second prepurge is complete
No main burner
•On/Off switch is off
•Igniter wires disconnected from CN5
•Multimeter set to "continuity check"
2000 OHMS scale
CHECK THAT:
• Tank is full of water
•
Exhaust and intake vent do not exceed allowable limits
• All plugs into boards are secure
• Condensate hose is drained and open
• 115-120 VAC is supplied to the heater (including polarity
check a neutral to ground check results in "0" volts reading)
• Proper (natural or propane) gas is supplied
STEP 1. Check continuity through the leads of the igniter.
STEP 1 - IGNITER CONTINUITY CHECK
IF…TH
E
a continuity range of 50-300 ohms is not present rep
a continuity range of 50-300 ohms is present re
a
Connector from CN5
Condition:

A. O. Smith Water Products Company Service Handbook
Irving, Texas 2000©Training Department
19
TROUBLESHOOTING
STEP 2 - CHECK CONTINUITY THROUGH THE VALVE COIL
STEP 2. Check Continuity Through The Valve
Coil
•Power off
•Gas valve - coil continuity check
•Disconnect wires from gas valve
•Multimeter set to scale.
IF…
meter does not indicate +/- 7.5% of table
meter indicates +/- 7.5% of table
BTH Model Gas OHMS Resistance
120 N 100
150, 199 N 560
150, 199 P 63
250 N 63
OHMS RESISTANCE TABLE
Usually a defective coil will be indicated by a "0" or "1" on the meter.