A.O. Smith BTH 120 Series How to use

MODELS COVERED: BTH 120 THRU 500
SERIES 100, 101 AND
BTH 400/500 SERIES 104
500 Tennessee Waltz Parkway
Ashland City, TN 37015
PRINTED IN THE U.S.A. 1012 316586-002
SERVICING SHOULD ONLY BE PERFORMED BY A QUALIFIED SERVICE TECHNICIAN
Service Handbook
COMMERCIAL GAS HIGH EFFICIENCY WATER HEATERS
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html

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Servicing should only be performed by a Qualied Service Technician
TABLE OF CONTENTS
INTRODUCTION ......................................................................2
QUALIFICATIONS .....................................................................2
TOOLS REQUIRED ....................................................................3
GENERAL INFORMATION...............................................................4
GAS PRESSURE SPECIFICATIONS ......................................................4
INSTALLATION QUICK TIPS – BTH 120AND 150: GAS PRESSURE.............................6
INSTALLATION QUICK TIPS – BTH 199AND 250 GAS PRESSURE .............................7
INSTALLATION QUICK TIPS – BTH 300, 400, 500 GAS PRESSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
INSTALLATION QUICK TIPS – BTH 300, 400, 500............................................9
INSTALLATION – VENTING CATEGORYAND MATERIALS ...................................10
VENTING TABLES – BTH 120 - 250 ......................................................11
VENTING TABLES – BTH 300, 400, 500...................................................11
CONCENTRIC VENTING...............................................................12
VENT CONDENSATION ...............................................................13
VENTING – ALL MODELS – SINGLE PIPE DIRECT VENT – USING OUTSIDEAIR TERMINATION
CLEARANCES SIDEWALL POWER VENT.................................................14
VENTING – ALL MODELS – TWO PIPE DIRECT VENT – USING OUTSIDE AIR TERMINATION
CLEARANCES SIDEWALL DIRECT VENT .................................................15
VENT TERMINATION – DIRECT VENT – ALL MODELS ......................................16
DIRECT VENTING – ALL MODELS.......................................................17
CONTROL OVERVIEW ................................................................18
ADJUSTING TANK TEMPERATURE – OPERATING SET POINT – DIFFERENTIAL.................20
CHANGING THE DISPLAY UNITS .......................................................22
FAULT AND WARNING CONDITIONS – ADVANCED DIAGNOSTIC INFORMATION ................24
ACCESS TO THE CURRENT FAULT OR WARNING .........................................25
FAULT CODES.......................................................................26
VIEWING THE FAULT HISTORY – VIEWING INFORMATION ABOUT THE HEATER................27
CONTROL SEQUENCE (TYPICALALL MODELS) ...........................................28
CONTROL SEQUENCE FLOW CHART ...................................................29
CONTROLS – CENTRAL CONTROL BOARD – CCB.........................................30
CONTROLS – GAS CONTROL VALVE BTH 120 ............................................32
CONTROLS – GAS CONTROL VALVE BTH 150 ............................................32
CONTROLS – GAS CONTROL VALVE BTH 199 AND 250.....................................33
CONTROLS – GAS CONTROL VALVE, ORIFICE CHART - BTH 300/400 - 100/101.................34
CONTROLS – GAS CONTROL VALVE, ORIFICE CHART – BTH 400/500 ........................35
CONTROLS – PRESSURE SWITCHES – ALL MODELS ......................................36
CONTROLS – PRESSURE SWITCHES – BTH 120 THROUGH 250 .............................37
CONTROLS – PRESSURE SWITCHES – BTH 300, 400, 500 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
CONTROLS – CONNECTIONS, IGNITER, FLAME SENSOR, SIGHT GLASS, POWEREDANODES ...39
HOT SURFACE IGNITER / FLAME SENSOR / CONTROL TIMING..............................40
BLOWER SPEED CONTROL BTH 199 AND 250 ............................................41
VARIABLE FREQUENCY DRIVE – BTH 400 AND 500........................................42
VARIABLE FREQUENCY DRIVE – BLOWER SPEED AND PRESSURE READINGS................43
WIRING DIAGRAM – BTH 120 - 300......................................................44
WIRING DIAGRAM – BTH 400, 500 ......................................................45

2Servicing should only be performed by a Qualied Service Technician
INTRODUCTION
The service handbook is designed to aid in servicing and troubleshooting A. O. Smith Cyclone Xi BTH
commercial 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 Corporation.
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 these products.
The information contained in this handbook is designed to answer commonly faced situations encountered
in the operation of this product line and is not meant to be all inclusive. If you are experiencing a problem
not covered in this handbook, please contact A. O. Smith Technical Information at 1-800-527-1953, by
email at [e-mail], or your local A. O. Smith Corporation representative for further assistance.
Our website at: http://www.hotwater.com is also a resource for installation and service information. 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
product’s instruction and operation manual.
QUALIFICATIONS
ANSI Z223.1 Sec 3.3.83
“Qualified Agency”
“Any individual, firm, corporation or company that either in person or through a representative is engaged
in and is responsible for (a) the installation, testing or replacement of gas piping or (b) the connection,
installation, testing, repair or servicing of appliances and equipment; that is experienced in such work; that
is familiar with all precautions required; and that has complied with all the requirements of the authority
having jurisdiction.”
Service of this water heater requires ability equivalent to that of a Qualified Service Technician in the field
involved. Installation skills such as plumbing, air supply, venting, gas supply, electrical supply are required
in addition to electrical testing skills. Some products may require combustion testing equipment and
certification. If you do not possess these skills or do not have the proper tools you should not attempt to
service this water heater.

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Servicing should only be performed by a Qualied Service Technician
TOOLS REQUIRED
• ELECTRICAL MULTIMETER CAPABLE OF MEASURING CONTINUITY/ OHMS, AC & DC VOLTS,
AMPERES, MICROAMPERES, MILLIVOLTS, and FREQUENCY (Hz)
• UEi Model DL289 or equivalent
• DIGITAL MANOMETER + 60" W. C. in .01" increments
Note: A digital manometer is required for testing pressure switches and can replace a gas pressure
gauge, draft gauge or slack tube manometer for checking gas pressure.
• UEi model EM200 or equivalent
• WATER PRESSURE GAUGE w/LAZY HANDAND HOSE BIBB CONNECTION
• THERMOMETER
• 1-1/16 INCH SOCKET WITH EXTENSION FOR POWEREDANODE REPLACEMENT
• SET OF NUMBERED DRILL BITS
DIGITAL MANOMETER DIGITAL MULTIMETER
WATER PRESSURE
TEST GAUGE W/LAZY
HAND AND HOSE BIBB
CONNECTION

4Servicing should only be performed by a Qualied Service Technician
GENERAL INFORMATION
INSTALLATION REQUIREMENTS FOR THE COMMONWEALTH OF MASSACHUSETTS
For all side wall terminated, horizontally vented power vent, direct vent, and power direct vent gas fueled
water heaters installed in every dwelling, building or structure used in whole or in part for residential
purposes, including those owned or operated by the Commonwealth and where the side wall exhaust vent
termination is less than seven (7) feet above finished grade in the area of the venting, including but not
limited to decks and porches, the following requirements shall be satisfied:
INSTALLATION OF CARBON MONOXIDE DETECTORS
At the time of installation of the side wall horizontal vented gas fueled equipment, the installing plumber
or gas fitter shall observe that a hard wired carbon monoxide detector with an alarm and battery backup
is installed on the floor level where the gas equipment is to be installed. In addition, the installing plumber
or gas fitter shall observe that a battery operated or hard wired carbon monoxide detector with an alarm
is installed on each additional level of the dwelling, building or structure served by the sidewall horizontal
vented gas fueled equipment. It shall be the responsibility of the property owner to secure the services of
qualified service technicians for the installation of hard wired carbon monoxide detectors. In the event that
the side wall horizontally vented gas fueled equipment is installed in a crawl space or an attic, the hard
wired carbon monoxide detector with alarm and battery back-up may be installed on the next adjacent
floor level. In the event that the requirements of this subdivision can not be met at the time of completion
of installation, the owner shall have a period of thirty (30) days to comply with the above requirements
provided that during said thirty (30) day period, a battery operated carbon monoxide detector with an alarm
shall be installed.
APPROVED CARBON MONOXIDE DETECTORS
Each carbon monoxide detector as required in accordance with the above provisions shall comply with
NFPA 720 and be ANSI/UL 2034 listed and CSAcertified.
SIGNAGE
A metal or plastic identification plate shall be permanently mounted to the exterior of the building at
a minimum height of eight (8) feet above grade directly in line with the exhaust vent terminal for the
horizontally vented gas fueled heating appliance or equipment. The sign shall read, in print size no less
than one-half (1/2") inch in size,
“GAS VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS.”
GAS PRESSURE SPECIFICATIONS
MODELS Natural
120‑150 Propane 120‑150 Natural 199‑250 Propane 199‑250 Natural 300/400/500 Propane 300/400/500
Maximum Gas
Supply Pressure 10.5" WC
(2.62 kPa) 14.0" WC (3.49 kPa) 10.5" WC (2.62 kPa) 14.0" WC (3.49 kPa) 11.0" WC (2.74 kPa) 14.0" WC (3.49 kPa)
Nominal Gas
Supply Pressure 7.0" WC
(1.74 kPa) 11.0" WC (2.74 kPa) 7.0" WC (1.74 kPa) 11.0" WC (2.74 kPa) 7.0" WC (1.74 kPa) 11.0" WC (2.74 kPa)
Minimum Gas
Supply Pressure
(Low Gas Press.
Switch Setting)
4.8" WC
(1.20 kPa) 11.0" WC (2.74 kPa) 4.8" WC (1.20 kPa) 8.5" WC (2.12 kPa) 5.2" WC (1.30 kPa) 11.0" WC (2.74 kPa)
Manifold Pressure 4.0" WC
(1.0 kPa) 10.0" WC (2.49 kPa) 0" WC (0 kPa) 0" WC (0 kPa) 4.0" WC (1.0 kPa) 10.0" WC (2.49 kPa)

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Servicing should only be performed by a Qualied Service Technician
GAS SUPPLY SYSTEMS
Lowpressurebuildinggassupplysystemsaredefinedasthosesystemsthatcannotunderanycircumstances
exceed 14” W.C. (1/2 PSI Gauge). These systems do not require pressure regulation. Measurements should
be taken to insure that gas pressures are stable and fall within the requirements stated on the water heater
rating plate. Readings should be taken with all gas burning equipment off (static pressure) and with all gas
burning equipment running at maximum rate (dynamic pressure). The gas supply pressure must be stable
within 1.5” W.C. (0.05 PSI Gauge) from static to dynamic pressure to provide good performance. Pressure
drops that exceed 1.5” W.C. (0.05 PSI Gauge) may cause rough starting, noisy combustion or nuisance
outages. Increases or spikes in static pressure during off cycles may cause failure to ignite or in severe
cases damage to appliance gas valves. If your low pressure system does NOT meet these requirements, the
installer is responsible for the corrections.
High pressure building supply systems use pressures that exceed 14” W.C. (1/2 PSI Gauge).These
systems must use field supplied regulators to lower the gas pressure to less than 14” W.C. (1/2 PSI Gauge).
Appliances require gas regulators that are properly sized for the water heater input and deliver the rating plate
specified pressures. Gas supply systems where pressure exceeds 5 PSI often require multiple regulators to
achieve desired pressures. Systems in excess of 5 PSI building pressure should be designed by gas delivery
professionals for best performance. Water heaters connected to gas supply systems that exceed 14” W.C.
(1/2 PSI Gauge) at any time must be equipped with a gas supply regulator.
The minimum supply pressure is measured while gas is flowing (dynamic pressure). The supply pressure
should be measured with all gas fired appliances connected to the common main firing at full capacity. If
the supply pressure drops more than 1.5” W.C. (0.05 PSI Gauge) as gas begins to flow to the water heater
then the supply gas system including the gas line and/or the gas regulator may be restricted or undersized.
See Supply Gas Regulator section of this manual. The gas valve on all models has a maximum gas supply
pressure limit of 14” W.C. (1/2 PSI Gauge). The maximum supply pressure is measured while gas is not
flowing (static pressure)
SUPPLY GAS REGULATOR
Install a positive lock-up gas pressure regulator in the gas supply line if inlet gas pressure exceeds the
maximum supply gas pressure at any time. see "Gas Pressure Specifications" Table on Page 4. Regulators
must be sized/used according to manufacturer’s specifications.
If a positive lock-up regulator is required follow these instructions:
1. Positive lock-up gas pressure regulators must be rated at or above the input Btu/hr rating of the water
heater they supply.
2. Positive lock-up gas pressure regulator(s) must be installed no closer than 3 equivalent feet (1 meter)
and no farther than 8 equivalent feet (2.4 meters) from the water heater’s inlet gas connection.
3. After installing the positive lock-up gas pressure regulator(s) an initial nominal supply pressure setting
of 7.0” w.c. (1.74 kPa) for Natural Gas and 11.0" w.c. (2.74 kPa) for Propane (LP) while the water
heater is operating is recommended and will generally provide good water heater operation. Some
additional adjustment maybe required later to maintain a steady gas supply pressure.
4. When installing multiple water heaters in the same gas supply system it is required that individual
positive lock-up gas pressure regulators be installed at each unit.

6Servicing should only be performed by a Qualied Service Technician
INSTALLATION QUICK TIPS – BTH 120 AND 150: GAS PRESSURE
ADJUSTMENT PROCEDURE: MANIFOLD GAS PRESSURE BTH 120 AND 150 MODELS
Main line gas pressure to the water heater for natural gas should be between a maximum of 10.5" w.c. (2.62
kPa) for natural gas, 14.0" w.c. (3.49 kPa) for propane and a minimum of 4.8 w.c. (1.20 kPa) for Natural
Gas, and 8.5" w.c. (2.12 kPa) for Propane Gas. Also see "Gas Pressure Specifications" Table on Page 4.
Asupply gas pressure regulator (service regulator) must be installed on the gas supply line no closer
than 3 equivalent feet (1 meter) and no farther than 8 equivalent feet (2.4 meters) from the water
heater's inlet gas connection if the gas pressure is above maximum pressure or not stable.
1. Check gas line pressure with a manometer.
2. Check manifold pressure gauge (manometer) connected to the manifold pressure tap on the gas
control valve. If manifold pressure adjustment is required, remove cover screw from top of the gas
control valve. Using a small screwdriver, turn adjusting screw clockwise to increase gas pressure or
counterclockwise to decrease gas pressure to obtain 4.0" w.c. (1.0 kPa) for natural gas and 10.0" w.c.
(2.49 kPa) for Propane (LP) Gas.
3. Cycle the burner on and off several times to check for proper operation.
4. Check the high limit and operating controls for proper operation.
5. Check the vent system seams and joints and ensure that there is no leakage of flue products into the
room.
6. Verify correct input rate (see below).
HIGH ALTITUDE INSTALLATIONS BTH 120 ‑ 150
For water heater installation locations with elevations above 6,500 feet (1982 meters) consult the “High
Altitude Installation” section of the owners manual.
1. Attach a pressure gauge (manometer) to the manifold pressure tap and refer to Page 4 for correct
pressure.
2. Use this formula to “clock” the meter. Be sure other gas consuming appliances are not operating
during this interval.
Btuh = 3600 X H/ T
T = Time in seconds to burn 1 cubic foot of gas.
(With a stopwatch read the gas meter and measure the amount of time required for the heater to
consume 1 cubic foot of gas.)
H = Heating value of gas (in Btu’s per cubic foot of gas).
Btuh = Actual heater input rate, in Btuh.
EXAMPLE: (Using BTH-150 heater)
T = 25.25 seconds
H = 1050 Btu/ft.3
BTUH = ?
Compare result to the de‑rated input required for the elevation at the installation location.
If it is necessary to adjust the gas pressure to the burner in order to obtain the full input rate, the steps
below should be followed:
1. Remove the pressure regulator cover screw and adjust the pressure by turning the adjusting screw
with a small screwdriver. Turn adjusting screw clockwise to increase gas pressure and input rate
and counterclockwise to decrease gas pressure and input rate. Do not exceed 4.0" (1.0 kPa) for
natural gas models and 10.0" w.c. (2.49 kPa) for propane models.

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Servicing should only be performed by a Qualied Service Technician
2. “Clock” the meter as in step (2) above.
3. Repeat steps (1) and (2) until the specified input rate is achieved.
4. Turn the manual gas control valve to “OFF”. Replace the pressure regulator cover screw. Remove
the pressure gauge or manometer from the manifold pressure tap and replace the set screw in
the manifold pressure tap. If the gas pressure regulator cannot be adjusted to give the full input
rating with sufficient gas pressure at the valve, check to ensure the unit is equipped with the correct
orifice. Refer to "ORIFICE CHART – BTH 120 thru 500" on Page 35.
INSTALLATION QUICK TIPS – BTH 199 AND 250 GAS PRESSURE
ADJUSTMENT PROCEDURE: MANIFOLD GAS PRESSURE BTH 199 AND 250 MODELS
IMPORTANT NOTE:
THE BTH 199 AND 250 MODELS INCORPORATE A NEW GAS CONTROL, WHICH OPERATES AT A
MANIFOLD PRESSURE OF 0" w.c. (0 kPa) FOR BOTH NATURALAND PROPANE GAS. SEE THE "GAS
PRESSURE SPECIFICATIONS" TABLE ON PAGE 4. THESE MODELS ARE CONFIGURED PRIOR
TO BEING SHIPPED FROM THE FACTORY AND NO ADJUSTMENTS ARE NECESSARY PRIOR TO
STARTUP. THE CONTROLLER MONITORS THE AIR FLOW AND MAKES ADJUSTMENTS TO THE FAN
SPEED WHICH, IN EFFECT, CONTROLS THE AMOUNT OF GAS FLOW. THEREFORE, THE UNIT WILL
SELF ADJUST TO ACQUIRE THE CORRECT AMOUNT OF INPUT.
Supply gas pressure to the water heater must not exceed a maximum of 10.5" w.c. (2.62 kPa) for natural
gas, or 14" w.c. (3.49 kPa) for propane. The minimum supply gas pressure is 4.8" w.c. (1.20 kPa) for
natural gas and 8.5" w.c. (2.12 kPa) for propane gas.
Once the unit is installed and filled with water and the inlet pressures confirmed, simply turn the switch
on and observe operation. Cycle the unit off and on several times to ensure proper operation. For more
information please refer to the Instruction Manual.
HIGH ALTITUDE INSTALLATION
The BTH 199 and 250 models are suitable for installation up to 10,100 feet above sea level with no
adjustments.
GAS ORIFICE
The BTH 199 and 250 models do not have a natural gas orifice. A .230" orifice is used on Propane (LP) gas
models.
Venturi
Gasket
w/o Orifice
Gas Control Without Orifice Natural Gas
Venturi
Gasket
w/LP Gas
Orifice
(.230")
Brass
Gas Control with .230" Propane (LP) Orifice
Asupply gas pressure regulator (service regulator) must be installed on the gas supply line no closer
than 3 equivalent feet (1 meter) and no farther than 8 equivalent feet (2.4 meters) from the water
heater's inlet gas connection if the gas pressure is above maximum pressure or not stable.

8Servicing should only be performed by a Qualied Service Technician
INSTALLATION QUICK TIPS – BTH 300, 400, 500 GAS PRESSURE
ADJUSTMENT PROCEDURE: MANIFOLD GAS PRESSURE BTH 300, 400, 500
A minimum dynamic gas supply pressure of 5.2" w.c. (1.30 kPa) for Natural Gas and 11" w.c.
(2.74 kPa) for Propane (LP) Gas is required before making any adjustment to the gas control
pressure regulator. Attempts to adjust the regulator during periods of low gas supply pressure could result
in over firing of the water heater when the gas supply pressure returns to normal.
Check gas line pressure with a manometer, adjust the gas supply line pressure "Gas Pressure
Specifications" table on Page 4.
1. Check manifold pressure using a pressure gauge (manometer) connected to the manifold pressure
tap on the gas control valve. If manifold pressure adjustment is required, remove cover screw from
top of the gas control valve. Using a small screwdriver, turn adjusting screw clockwise to increase
gas pressure or counter clockwise to decrease gas pressure to obtain 4.0" w.c. (1.0 kPa) for Natural
Gas and 10" w.c. (2.49 kPa) for Propane (LP) gas.
2. Cycle the burner on and off several times to check for proper operation.
3. Check the high limit and operating controls for proper operation.
4. Check the vent system seams and joints and ensure that there is no leakage of flue products into
the room.
5. Verify correct input rate as shown on Page 6.
HIGH ALTITUDE ADJUSTMENT BTH 300, 400, 500
For high altitude adjustments, contact the help line number on the front of the water heater or contact
[e-mail].

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Servicing should only be performed by a Qualied Service Technician
INSTALLATION QUICK TIPS – BTH 300, 400, 500
SEE MANUAL FOR COMPLETE INSTALLATION INSTRUCTIONS & DETAILS

10 Servicing should only be performed by a Qualied Service Technician
INSTALLATION – VENTING CATEGORY AND MATERIALS
CYCLONE VENTING
Category IV • Positive pressure in vent, above atmospheric.
• These models will produce excessive condensate in vent.
• Vent system must not be combined with any other appliances.
• Condensing water heater, thermal efficiency of this product will produce condensate in
the vent system, the heater is equipped with provision for draining condensate from vent
system.
• PH of condensate approximately 3.59; within tolerance for cast iron drains.
Type venting • May be installed Direct Vent; draws all fresh air for combustion from and discharges flue
gases to the outdoor atmosphere through 2 pipes.
• May be installed Conventional Vent; uses room air for combustion and discharges flue
gases to the outdoor atmosphere through 1 pipe.
Vertical and horizontal Vent system can be terminated vertically or horizontally (side wall).
Vent materials • PVC schedule 40.
• CPVC schedule 40.
• ABS schedule 40.
Concentric Venting Concentric vent kits for all models.

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Servicing should only be performed by a Qualied Service Technician
VENTING TABLES – BTH 120 ‑ 250
Maximum equivalent feet of intake and vent pipe using 3" PVC is 50 feet (15.2 m). Equivalent feet must
include any 90° elbows (two 45° elbows equal one 90° elbow). Three inch diameter 90° elbows are
equivalent to 5' (1.5 m) of pipe.
Maximum equivalent feet of intake and vent pipe using 4" PVC is 120 feet (36.6 m). Equivalent feet
must include any 90° elbows (two 45° elbows equal one 90° elbow). Four inch diameter 90° elbows are
equivalent to 5' (1.5 m) of pipe. If vent size is increased to extend the maximum allowed distance, it cannot
be decreased again anywhere in the vent run.
Vent Length Table Equivalent Feet (Meters) 120 through 250
Number of 90° Elbows 3" Minimum Pipe (Ft./M.) 3" Maximum Pipe (Ft./M.) 4" Maximum Pipe (Ft./M.)
ONE (1) 7/2.1 45/13.7 115/35
TWO (2) 7/2.1 40/12.2 110/33.5
THREE (3) 7/2.1 35/10.7 105/32
FOUR (4) 7/2.1 30/9.1 100/30.5
FIVE (5) 7/2.1 — 95/29
SIX (6) 7/2.1 — 90/27.4
VENTING TABLES – BTH 300, 400, 500
Maximum equivalent feet of intake and vent pipe using 4" PVC is 70 feet (21.3 m). Equivalent feet must
include any 90° elbows (two 45° elbows equal one 90° elbow). Four inch diameter 90° elbows are equivalent
to 5' (1.5 m) of pipe.
Maximum equivalent feet of intake and vent pipe using 6" PVC is 120 feet (36.6 m). Equivalent feet must
include any 90° elbows (two 45° elbows equal one 90° elbow). Six inch diameter 90° elbows are equivalent
to 5' (1.5 m) of pipe.
Vent Length Table Equivalent Feet (Meters) 300, 400, 500
Number of 90° Elbows 4" PVC Maximum
Feet/meters of Pipe (Ft./M.) 6" PVC Maximum Feet/meters of Pipe (Ft./M.)
ONE (1) 65'/19.7 115'/35.0
TWO (2) 60'/18.2 110'/33.5
THREE (3) 55'/16.7 105'/32.0
FOUR (4) 50'/15.2 100'/30.5
FIVE (5) 45'/13.6 95'/29.0
SIX (6) 40'/12.1 90'/27.4

12 Servicing should only be performed by a Qualied Service Technician
CONCENTRIC VENTING
Concentric venting allows for a single wall penetration. For multiple water heater installation using this vent
practice, any additional vents of this type may be located 12" (30.5 cm) on centerline to either side of the
first vent or 12" (30.5 cm) on centerline vertically above the first vent. Concentric kits may be extended to a
maximum allowable length of 5 feet (152 cm). Schedule 40 PVC pipe must be carefully measured and cut
to the desired length. Do not use couplings when extending the length of a concentric termination. The use
of couplings will restrict the flow through the termination and may cause improper combustion. For more
information please refer to the Instruction Manual.
BTH Concentric Vent for 120 through 250.
BTH Concentric Vent for 300 through 500.

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Servicing should only be performed by a Qualied Service Technician
VENT CONDENSATION
4” PIPE FIELD
SUPPLIED
EXHAUST ELBOW
VENT CONNECTION
FACTORY INSTALLED
6” PIPE FIELD
SUPPLIED
6” x 4” REDUCER
FIELD SUPPLIED
VENT (EXHAUST) CONNECTION
Failure to properly install the drain line on the condensate elbow will result in a water heater shut
down and a “blocked exhaust” fault message.
The average dew point of natural gas flue products is 127 °F (53 °C) . Propane flue products is 119 °F (48
°C). With 70 °F (21 °C) ambient air temperature and 180 °F (82 °C) stored water temperature, exhaust gas
will be approximately 140 °F (60 °C) .
Q. CAN I DRAIN THIS CONDENSATION TO THE FLOOR DRAIN?
A. Yes, this condensation can be drained to the floor drain. The “Corrosion Resistance of Cast Iron Soil Pipe”
by the Ductile MetalsAssociation (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.”
Q. HOW DO THE PH VALUES OF CONDENSATE AND CARBONATED COLA DRINK COMPARE?
A. 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 concentrated
than the BTH condensate.
Q. WHAT DOES THE PH SCALE MEAN?
A. 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.
Q. WHAT ABOUT CONDENSATE NEUTRALIZERS?
A. 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.

14 Servicing should only be performed by a Qualied Service Technician
VENTING – ALL MODELS – SINGLE PIPE DIRECT VENT – USING OUTSIDE AIR
TERMINATION CLEARANCES SIDEWALL POWER VENT
V X
VENT TERMINAL AIR SUPPLY INLETAREA WHERE TERMINAL IS NOT PERMITTED
v
v
A
G
V
FIXED
CLOSED
FIXED
CLOSED
OPERABLE OPERABLE
V
CBB
B
B
F
B
V
V
A
J
V
H
M
XX
V
V
K
B
E
D
L
POWER VENT
(using room air for combustion)
EXTERIOR CLEARANCES FOR SIDEWALL VENT TERMINATION
Figure 1
Ventterminalclearancesfor“PowerVent”installations.PowerVentcongurationsuseroomairforcombustion.
CANADIAN INSTALLATIONS 1US INSTALLATIONS 2CANADIAN INSTALLATIONS 1US INSTALLATIONS 2
AClearance above grade,
veranda, porch, deck or
balcony 12 inches (30 cm) 12 inches (30 cm) HClearance to each side
of center line extended
above meter/regulator
assembly
3 feet (91 cm) within a height 15 feet
(4.5 m) above the meter/
regulator assembly
3 feet (91 cm) within a
height 15 feet (4.5 m)
above the meter/regulator
assembly*
BClearance to window
or door that may be
opened
6 inches (15 cm) for appliances up to
10,000 Btu/hr (3 kW), 12 inches (30
cm) for appliances between 10,000
Btu/hr (3 kW) and 100,000 Btu/hr (30
kW), 36 inches (91 cm) for appliances
above 100,000 Btu/hr (30 kW)
4 feet (1.2 m) below
or to side of opening;
1 foot (30 cm) above
opening IClearance to service
regulator vent outlet
3 feet (91 cm) 3 feet (91 cm)*
CClearance to
permanently closed
window 12 inches (30 cm)* 12 inches (30 cm)* J
Clearance to a non
mechanical air supply
inlet into building or
combustion air inlet to
any other appliance
6 inches (15 cm) for appliances up
to 10,000 Btu/hr (3 kW), 12 inches
(30 cm) for appliances between
10,000 Btu/hr (3 kW) and 100,000
Btu/hr (30kW), 36 inches (91cm)
for appliances above 100,000 Btu/
hr (30 kW)
4 feet (1.2 m) below or to
side of opening; 1 foot
(30 cm) above opening.
D
Vertical clearance to
ventilated soft located
above the terminal
within a horizontal
distance of 2 feet (61
cm) from the center line
of the terminal
12 inches (30 cm)* 12 inches (30 cm)* KClearance to a mechanical air supply
inlet 6 feet (1.83 m)
3 feet (91 cm) above if
within
10 feet (3 m) horizontally
EClearance to
unventilated soft 12 inches (30 cm)* 12 inches (30 cm)* LClearance above paved
sidewalk or paved
driveway located on
public property
7 feet (2.13 m)† 7 feet (2.13 m)
FClearance to outside
corner 2 feet (60 cm)* 2 feet (60 cm)* MClearance under
veranda, porch, deck, or
balcony 12 inches (30 cm) ‡ 12 inches (30 cm) ‡
GClearance to inside
corner 8 feet (2.44 m)* 8 feet (2.44 m)*
1 In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code.
2 In accordance with the current ANSI Z223.1/NFPA 54, National Fuel Gas Code.
† A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
‡ Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the oor.
* Clearance in accordance with local installation codes and the requirements of the gas supplier and the manufacturer’s installation instructions.

15
Servicing should only be performed by a Qualied Service Technician
VENTING – ALL MODELS – TWO PIPE DIRECT VENT – USING OUTSIDE AIR
TERMINATION CLEARANCES SIDEWALL DIRECT VENT
V X
VENT TERMINAL AIR SUPPLY INLETAREA WHERE TERMINAL IS NOT PERMITTED
v
v
A
G
V
FIXED
CLOSED
FIXED
CLOSED
OPERABLE OPERABLE
V
CBB
B
B
F
B
V
V
A
J
V
H
M
XX
V
V
K
B
E
D
L
DIRECT VENT
(using outdoor air for combustion)
EXTERIOR CLEARANCES FOR SIDEWALL VENT TERMINATION
Figure 2
Ventterminalclearancesfor“DirectVent”installations.DirectVentcongurationsuseoutdoorairforcombustion.
CANADIAN INSTALLATIONS 1US INSTALLATIONS 2CANADIAN INSTALLATIONS 1US INSTALLATIONS 2
AClearance above grade,
veranda, porch, deck or
balcony 12 inches (30 cm) 12 inches (30 cm) HClearance to each side
of center line extended
above meter/regulator
assembly
3 feet (91 cm) within a height 15
feet (4.5 m) above the meter/
regulator assembly
3 feet (91 cm) within a height
15 feet (4.5 m) above the
meter/regulator assembly*
BClearance to window or
door that may be opened
6 inches (15 cm) for appliances
up to 10,000 Btu/hr (3 kW), 12
inches (30 cm) for appliances
between 10,000 Btu/hr (3 kW)
and 100,000 Btu/hr (30 kW), 36
inches (91 cm) for appliances
above 100,000 Btu/hr (30 kW)
6 inches (15 cm)
for appliances up to
10,000 Btu/hr (3 kW),
9 inches (23 cm) for
appliances between
10,000 Btu/hr (3 kW)
and 50,000 Btu/hr (15
kW), 12 inches (30 cm)
for appliances above
50,000 Btu/hr (15 kW)
IClearance to service
regulator vent outlet 3 feet (91 cm) 3 feet (91 cm)*
CClearance to
permanently closed
window 6 inches (15 cm)* 6 inches (15 cm)* J
Clearance to a non
mechanical air supply
inlet into building or
combustion air inlet to
any other appliance
6 inches (15 cm) for appliances up
to 10,000 Btu/hr (3 kW), 12 inches
(30 cm) for appliances between
10,000 Btu/hr (3 kW) and 100,000
Btu/hr (30 kW), 36 inches (91 cm)
for appliances above 100,000 Btu/
hr (30 kW)
6 inches (15 cm) for
appliances up to 10,000
Btu/hr (3 kW), 9 inches (23
cm) for appliances between
10,000 Btu/hr (3 kW) and
50,000 Btu/hr (15 kW), 12
inches (30 cm) for appliances
above 50,000 Btu/hr (15 kW)
D
Vertical clearance to
ventilated soft located
above the terminal within
a horizontal distance of
2 feet (61 cm) from the
center line of the terminal
12 inches (30 cm)* 12 inches (30 cm)* KClearance to a
mechanical air supply
inlet 6 feet (1.83 m) 3 feet (91 cm) above if within
10 feet (3 m) horizontally
EClearance to unventilated
soft 12 inches (30 cm)* 12 inches (30 cm)* LClearance above
paved sidewalk or
paved driveway located
on public property
7 feet (2.13 m)† 7 feet (2.13 m)†*
FClearance to outside
corner 2 feet (60 cm)* 2 feet (60 cm)* MClearance under
veranda, porch, deck,
or balcony 12 inches (30 cm) ‡ 12 inches (30 cm) ‡*
GClearance to inside
corner 8 feet (2.44 m)* 8 feet (2.44 m)*
1 In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code.
2 In accordance with the current ANSI Z223.1/NFPA 54, National Fuel Gas Code.
† A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and serves both dwellings.
‡ Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the oor.
* Clearance in accordance with local installation codes and the requirements of the gas supplier and the manufacturer’s installation instructions.

16 Servicing should only be performed by a Qualied Service Technician
VENT TERMINATION – DIRECT VENT – ALL MODELS
WHEN LOCATING THE TERMINALS ON A SIDEWALL, THE FOLLOWING SPECIFICATIONS
PERTAINING TO TERMINAL LOCATION MUST BE FOLLOWED.
1. The intake vent terminal and the exhaust vent terminal must terminate on the same exterior wall and
must be located at a minimum of 24" (61cm) from the vertical centerline of the exhaust vent terminal
(see Figure below). In colder climates increasing this separation to at least 48" (122 cm) will reduce
possibility of frost over from side winds blowing exhaust vapors to the air intake of the direct vent.
2. The horizontal centerline of the intake vent terminal may not be located lower than the horizontal
centerline of the exhaust vent terminal.

17
Servicing should only be performed by a Qualied Service Technician
DIRECT VENTING – ALL MODELS
The air intake provided on the unit contains an air intake screen to prevent large particles from entering the
unit. WHEN THE UNIT IS TO BE SET UP AS A DIRECT VENT, THE BALANCE PLATE AND AIR INTAKE
SCREEN MUST BE REMOVED BEFORE GLUING PIPE TO THE CONNECTOR. THE INLET VENT PIPE
MAY THEN BE GLUED TO THE AIR INTAKE PROVIDED ON THE UNIT.
Remove the balance plate (BTH400/
500 only) and air intake screen before
gluing intake air pipe to the fitting.
45° PVC Elbow
3" 120-250
4" 300-500
Two 3" or 4" 45° PVC elbows with air intake screens are provided with each unit. Both elbows are to be
used in direct vent applications. The screens are provided to keep vermin and large debris from entering
the intake air and exhaust vent runs.
AIR INTAKE SCREEN

18 Servicing should only be performed by a Qualied Service Technician
CONTROL OVERVIEW
Interaction with the water heater controller is through an LCD display called the User Interface Module
(UIM). This screen is also referred to as the “desktop” or “desktop menu”. Up and down buttons and
three operation buttons allow navigation through the control menus and to make adjustments to the water
heater. Operation of the three lower buttons is defined immediately above them on the screen.
While the water heater is operating, the user interface will display the desktop screen (if there are no active
faults or warnings).
An example of this screen is shown below.
• The first temperature on this screen is the temperature of the water inside the tank.
• The second temperature on this screen is the Operating Set Point. The Operating Set Point is the
temperature at which the water heater will maintain the water inside the tank.
• The third line on the screen is a text description of the Operational State of the water heater. The
operational state of the water heater is also indicated graphically by status icons.