A.O. Smith VB/VW 1500, 2000 User manual

1
WARNING: If the information in this
manual is not followed exactly, a re or
explosion may result causing property
damage, personal injury or loss of life.
— Do not store or use gasoline or other
ammable vapors and liquids in the
vicinity of this or any other appliance.
— WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Do not touch any electrical switch; do
not use any phone in your building.
• Immediately call your gas supplier
from a neighbor’s phone. Follow the
gas supplier’s instructions.
• If you cannot reach your gas supplier,
call the re department.
— Installation and service must be
performed by a qualied installer,
service agency or the gas supplier.
PRINTED 0710 317294-000
INSTRUCTION MANUAL
MODELS:
VB/VW 1500, 2000
SERIES 100/101
GAS-FIRED COPPER BOILERS FOR
HYDRONIC HEATING AND HOT WATER SUPPLY
• Installation
• Operation
• Maintenance
• Limited Warranty
500 Tennessee Waltz Parkway
Ashland City, TN 37015
500 Tennessee Waltz Parkway
Ashland City, TN 37015
www.hotwater.com

2
Vertical Installation Requirements ............................................. 18
Horizontal Installation Requirements ........................................18
Direct Vent Installation Requirements ...................................... 18
Installation Requirements for the Commonwealth of Mass.... 20
SYSTEM INSTALLATION ................................................................. 23
General ......................................................................................... 23
Hot Water Heating (Hydronic) System ......................................... 23
Internal Contaminants ................................................................... 24
Hot Water Supply System General Water Line Connections ...... 24
Hard Water Conditions ................................................................. 25
Thermal Expansion (Closed System)............................................ 25
Gas Connections ........................................................................... 25
Field Wiring ................................................................................... 26
SUGGESTED PIPE SIZING TABLES................................................ 27
PIPING DIAGRAMS ......................................................................28-30
SCHEMATIC DIAGRAM..................................................................... 31
WIRING DIAGRAM .......................................................................32-33
OPERATION ....................................................................................... 34
Important ........................................................................................ 34
General ......................................................................................... 34
Filling and Purging for Heating Boiler Installation ......................... 34
Filling for Hot Water Supply Boiler Installation .............................. 34
Purging Gas Line .......................................................................... 34
Inlet Gas Pressure ........................................................................ 34
Water Temperature Regulation...................................................... 35
Manifold Pressure Connections ................................................... 35
LIGHTING AND OPERATING INSTRUCTIONS ............................... 36
Adjustment ..................................................................................... 37
Setting of the Test Mode ................................................................ 37
Control System .............................................................................. 37
Inputs to MCB ................................................................................ 38
Dipswitches...............................................................................38-39
Operating Sequence...................................................................... 39
Operating Setpoint Adjustment Procedure.................................... 41
TROUBLESHOOTING IGNITION SYSTEM...................................... 43
Troubleshooting Gas Valve............................................................ 44
PREVENTATIVE MAINTENANCE..................................................... 44
Main Burner ..............................................................................44-45
Relief Valve .................................................................................... 45
Blower Compartment ..................................................................... 45
Burner Maintenance ...................................................................... 45
Condensate Removal System....................................................... 45
Venting Maintenance ..................................................................... 46
Heat Exchanger Preventive Maintenance..................................... 46
Tube Cleaning Procedure ............................................................. 46
Replacement Parts ........................................................................ 46
LIMITED WARRANTY........................................................................ 43
TABLE OF CONTENTS .......................................................................2
SAFE INSTALLATION, USE, AND SERVICE ...................................3
APPROVALS ..........................................................................................3
GENERAL SAFETY........................................................................... 4-5
INTRODUCTION ..................................................................................6
DIMENSION AND CAPACITY DATA ............................................ 6-7
CAPACITY AND FLOW DATA.............................................................8
CONTROL COMPONENTS ............................................................ 8-9
The Control System.........................................................................8
Hot Surface Igniter .........................................................................8
Pressure Switches ..........................................................................8
Low Gas Switch .............................................................................9
Low Gas Pressure Switch ..............................................................9
Gas Valve..........................................................................................9
Flow Switch.......................................................................................8
Flame Sensor....................................................................................9
Water Temperature Limit Controls................................................10
On/Off Switch..................................................................................10
Circulating Pump ............................................................................10
Temperature Probes .......................................................................10
Low Water Cutoff (Optional).........................................................10
Pressure Relief Valve ...............................................................10-11
GENERAL
Required Ability ............................................................................... 11
Location ..........................................................................................11
Replacing Existing Common Vented Boiler ...........................11-12
Panels and Covers ........................................................................12
Chemical Vapor Corrosion ..........................................................12
Installation Clearances .................................................................12
Leveling ..........................................................................................12
Air Requirements ............................................................................12
 Unconned Space ..........................................................................12
 Conned Space ..............................................................................12
 Fresh Air Openings For Conned Spaces .................................13
Outdoor Air Through Two Openings............................................13
Outdoor Air Through One Opening .............................................13
Outdoor Air Through Two Horizontal Ducts ...............................13
Outdoor Air Through Two Vertical Ducts....................................14
Air From Other Indoor Spaces ....................................................14
Termination Clearances Sidewall Power Vent ............................15
Termination Clearances Sidewall Direct Vent .............................16
VENTING ..............................................................................................17
Special Installation Considerations . ............................................17
Venting System Using AL 29-4C® ............................................17
General Exhaust Vent Installation Procedure.............................17
Connecting Vent to Boiler ...........................................................17
Venting Supports ..........................................................................18
TABLE OF CONTENTS

3
The proper installation, use and servicing of this boiler is extremely important to your safety and the safety of others.
Many safety-related messages and instructions have been provided in this manual and on your boiler to warn you and others of a
potential injury hazard. Read and obey all safety messages and instructions throughout this manual. It is very important that the
meaning of each safety message is understood by you and others who install, use, or service this boiler.
DANGER indicates an imminently
hazardous situation which, if not avoided,
will result in injury or death.
This is the safety alert symbol. It is used to alert you to
potential personal injury hazards. Obey all safety
messages that follow this symbol to avoid possible
injury or death.
WARNING indicates a potentially hazardous
situation which, if not avoided, could result
in injury or death.
CAUTION indicates a potentially hazardous
situation which, if not avoided, could result in
minor or moderate injury.
CAUTION used without the safety alert
symbol indicates a potentially hazardous
situation which, if not avoided, could result in
property damage.
WARNING
CAUTION
CAUTION
DANGER
All safety messages will generally tell you about the type of hazard, what can happen if you do not follow the safety message, and how
to avoid the risk of injury.
The California Safe Drinking Water and Toxic Enforcement Act requires the Governor of California to publish a list of substances known
to the State of California to cause cancer, birth defects, or other reproductive harm, and requires businesses to warn of potential
exposure to such substances.
This product contains a chemical known to the State of California to cause cancer, birth defects, or other reproductive harm. This
appliance can cause low level exposure to some of the substances listed in the Act.
IMPORTANT DEFINITIONS
• Gas Supplier: The Natural Gas or Propane Utility or service who supplies gas for utilization by the gas burning
appliances within this application. The gas supplier typically has responsibility for the inspection and code approval of
gas piping up to and including the Natural Gas meter or Propane storage tank of a building. Many gas suppliers also
offer service and inspection of appliances within the building.
SAFE INSTALLATION, USE AND SERVICE
APPROVALS

4
GENERAL SAFETY
Breathing Hazard - Carbon Monoxide Gas
Special consideration must be taken
with installation above 4500 feet.
Please contact an A. O. Smith qualified
service agent to obtain the proper
setup and instructions before lighting.
Failure to implement the proper setup will
result in improper and inefficient operation
of the appliance resulting in production of
increased levels of carbon monoxide gas
in excess of the safe limits which could
result in serious personal injury or death.
Breathing carbon monoxide can cause brain damage or
death. Always read and understand instruction manual.

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GENERAL SAFETY
GROUNDING INSTRUCTIONS
This boiler must be grounded in accordance with the National Electrical
Code, Canadian Electrical Code and/or local codes. Boiler is polarity
sensitive; correct wiring is imperative for proper operation.
This boiler must be connected to a grounded metal, permanent
wiring system, or an equipment grounding conductor must be
run with the circuit conductors and connected to the equipment
grounding terminal or lead on the boiler.
INLET WATER CONSIDERATIONS
To minimize the amount of condensate, a minimum inlet
water temperature to the heat exchanger of 120°F (49°C)
should be maintained. This temperature can be acquired by
returning 120°F (49°C) water from the remote storage tank
to the boiler or by installing a by-pass loop between the
boiler’s inlet and outlet connections. When installing a by-
pass loop, a remote temperature probe must be used, see
SYSTEM INSTALLATION.
Circulating water through the boiler and to the remote storage
tank (if applicable) is accomplished by a pump on VW models
only. For hot water heating systems using the VB model,
the circulating pump is NOT provided on standard models
(optional) and must be field installed.
CORRECT GAS
Make sure the gas on which the boiler will operate is the same as
thatspeciedontheboilerratingplate.Donotinstalltheboilerif
equipped for a different type of gas — consult your supplier.
PRECAUTIONS
If the unit is exposed to the following, do not operate until all
correctivestepshavebeenmadebyaqualiedserviceman:
 1. Exposuretore.
2. If damaged.
3. Firing without water.
4. Sooting.
Iftheboilerhasbeenexposedtoooding,itmustbereplaced.
LIQUEFIED PETROLEUM GAS MODELS
Boilersforpropaneorliqueedpetroleumgas(LPG)aredifferent
from natural gas models. A natural gas boiler will not function safely
on LP gas and no attempt should be made to convert a boiler from
natural gas to LP gas.
LP gas must be used with great caution. It is highly explosive
andheavierthanair.Itcollectsrstinthelowareasmakingits
odordifculttodetectatnoselevel.IfLPgasispresentoreven
suspected, do not attempt to nd the cause yourself. Leave
the building, leaving doors open to ventilate, then call your gas
supplier or service agent. Keep area clear until a service call has
been made.
At times you may not be able to smell an LP gas leak. One cause
is odor fade, which is a loss of the chemical odorant that gives
LP gas its distinctive smell. Another cause can be your physical
condition, such as having a cold or diminishing sense of smell
with age. For these reasons, the use of a propane gas detector
is recommended.
If you experience an out of gas situation, do not try to relight
appliances yourself. Call your local service agent. Only trained
LP professionals should conduct the required safety checks in
accordance with industry standards.
HIGH ALTITUDE INSTALLATIONS
Rated inputs are suitable up to 4500 feet (1370 m) elevation. Consult
the factory for installation at altitudes over 4500 feet (1370 m).
FIELD INSTALLED COMPONENTS
When installing the boiler, the following components MUST
beinstalled:
1) Circulating Pump (Hydronic)
2) Remote Temperature Probe
3) Storage Tank T&P Relief Valve
4) Manual Gas Shutoff Valve (Supply)
5) Boiler Water Bypass Loop
Check FEATURES AND CONTROLS section for further information.

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DIMENSION AND CAPACITY DATA
VB/VW DIMENSIONS
VW PUMP MOUNT DIMENSIONS
FIGURE 1.
This design complies with the current edition of the ANSI
Z21.13 - CSA 4.9 Standard for Gas Fired Low Pressure Steam
and Hot Water Boilers.
Compliance under this standard implies that when the boiler
underwent test, the gas manifold and control assembly provided
on the boiler met safe lighting and other performance criteria.
Detailed installation diagrams are found in this manual. These
diagrams will serve to provide the installer a reference for the
materials and methods of piping necessary. It is essential that
all water, gas piping and wiring be installed as shown on the
diagrams. You should thoroughly read and understand this
manual before installation and/or operation of this boiler.
The factory warranty will be void if the boiler(s) have been
improperly installed or operated.
AL 29-4C® is a registered trademark of Allegheny Ludlum Corporation.
The installation must conform to all instructions contained in
this manual and the local code authority having jurisdiction.
These should be carefully followed in all cases. Authorities
having jurisdiction should be consulted before installation
begins if there are any questions regarding compliance with
local, state or national codes.
In the absence of local codes, the installation must comply
with the current editions of the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 and the National Electrical Code, NFPA 70 or
CAN/CSA-B149.1, the Natural Gas and Propane Installation
Code and CSA C22.1, the Canadian Electrical Code.
Where required by the authority having jurisdiction, the installation
must conform to the Standard for Controls and Safety Devices
from Automatically Fired Boilers, ANSI/ASME CSD-1.
All documents are available from the Canadian Standards
Association, 8501 East Pleasant Valley Road, Cleveland,
OH 44131. NFPA documents are also available from the
National Fire Protection Association, 1 Batterymarch Park,
Quincy, MA 02269.
INTRODUCTION

7
TABLE 1. GAS AND ELECTRICAL CHARACTERISTICS
Models Manifold Pressure Maximum Supply Pressure Minimum Supply Pressure
Type of Gas Inches W.C. kPa Inches W.C. kPa Inches W.C. kPa
VB/VW-1500,2000 Natural -.2 to - 4.9 -.04 to - 1.22 14.0 3.49 4.0 1.0
VB/VW-1500,2000 Propane -.2 to - 4.9 -.04 to - 1.22 14.0 3.49 8.0 2.0
ElectricalPower:120v,60hz,and30amps.
TABLE 2. ROUGH IN DIMENSIONS
Models VB/VW-1500 VB/VW-2000
Dimensions inches mm inches mm
Flue Outlet Diameter 7178 7178
Air Intake Diameter 6152 6152
Water Inlet 2.5 inch NPT
Water Outlet 2.5 inch NPT
Gas Inlet 1. 2 5 inch NPT
A67 1829 72 1702
B30.5 775 30.5 775
C37 940 37 940
D57 1575 62 1435
E43 1219 48 1092
F16.5 419 16.5 419
G8.5 216 8.5 216
H15 381 15 381
J5127 5127
K15 381 15 381
L8203 8203
M21 533 21 533
N48 1219 48 1219
P2.5 64 2.5 64
Q61 1549 61 1549
R22.4 594 23.4 569

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CAPACITY AND FLOW DATA
TABLE 3. RECOVERY CAPACITIES
Model
No.
Input
Rating
(Btu/hr)
Output
Rating
(Btu/hr)
Water
Flow
Temperature Rise - ΔT °F (°C)
20 40 60 80 90 100 120 140
(11) (22) (33) (44) (50) (56) (67) (78)
VW-1500 1,500,000 1,260,000 GPH 7,560 3,780 2,520 1,890 1,680 1,512 1,260 1,080
LPH 28,615 14,307 9,538 7,154 6,359 5,723 4,769 4,088
VW-2000 2,000,000 1,680,000 GPH 10,080 5,040 3,360 2,520 2,240 2,016 1,680 1,440
LPH 38,153 19,076 12,718 9,538 8,478 7,631 6,359 5,450
THE CONTROL SYSTEM
The control system consists of 5 basic components:
1)The Modulation control board (MCB) 2) The Power distribution board
(PDB) 3) Blocked Inlet Pressure Switch (BIS) 4) Blower Prover Switch
(BPS) 5) Blocked Flue Switch (BFS). See Figure 2. The Modulation
Control Board is located in the control box and can be accessed
by opening the front door of the unit. The User Interface Module is
attached to the front door panel. Every system will have one Modulation
Control Board (MCB), one Power Distribution Board (PDB), and one
User Interface Module (UIM).
TheMCBcontainsdipswitcheswhichareusedtoconguretheboiler
for several different control options, see the Control System Section.
FIGURE 2.
HOT SURFACE IGNITER
The Hot Surface Igniter is a device that ignites the main burner, see
Figure3.When120VACisappliedtotheigniter,sufcientheatis
generated to ignite the main burner. Although improvements have
been made to strengthen the igniter, it is still fragile and care must
be taken in handling the igniter to prevent breakage.
FIGURE 3.
PRESSURE SWITCHES
This control system has 3 pressure switches that are standard. Blocked
Inlet Pressure Switch (BIS), Blower Prover Switch (BPS) Blocked
Flue Switch (BFS).
The BPS on this model is a normally open switch that closes on
increased vacuum. Once the blower moves enough air to create a
vacuum across the Venturi the BPS is activated. If the blower fails
orcannotmovesufcientairasoftlockoutwilloccur.Inspectthe
blower for correct operation.
The Blocked Inlet Switch (BIS) will activate is the intake is blocked
only during the heating cycle. The BIS is a normally closed pressure
switch that opens when the air intake is blocked. If the BIS is activated
check and clear the intake of any obstructions.
Theblockeduepressureswitch(BFS)activatedwhentheexhaust
ueoftheunitisrestrictedorblocked.TheBFSisanormallyclosed
switch that opens when positive pressure is placed on the switch
because of any restriction to the exhaust venting. If the BFS is activated
check and clear any obstructions causing the restriction.
FIGURE 4.
CONTROL COMPONENTS

9
LOW GAS SWITCH
This VF boiler is available with a low gas pressure switch which
meets the CSD-1 code requirements, see Figure 5.
The Low Gas Pressure Switch (LGPS) is normally closed and remains
closed unless the pressure falls below the preset pressure.
FIGURE 5.
LOW GAS PRESSURE SWITCH.
GAS VALVE
The Gas valve is a normally closed servo regulated gas valve. The
valve opens only when energized by the MCB control board and
closes when the power is removed. The MCB supplies 120 volts to
the gas valve during operation.
FLOW SWITCH
Theowswitchpicturedingure6activateswhensufcientow
hasbeenestablished.Switchwillnotclosewhenowisrestricted
or is not present
FIGURE 6. WATER FLOW SWITCH.
FLAME SENSOR
EachBoilerisequippedwithtwoamesenorscoupledtogetherto
detectthepresenceoftheburneramesathighandlowreconditions.
Theseamerodsworktogetherasonetosensetheame.Ifno
ameissensed,thegasvalvewillcloseautomatically.Onstandard
modelsifnoameissensedonthreeignitiontrials,theboilerwill
lock out. In the event of a lockout, depress the SELECT button on
the display board to restart the boiler.

10
WATER TEMPERATURE LIMIT CONTROLS
The “V(B/W)” models incorporate an outlet water probe consisting
oftwolimitcontrols:
1. A Manual Reset High limit control that can be set as high as either
210°F (99°C) or 235°F (113°C), depending on the application.
2. A xed manual high limit, factory set at 244°F (118°C). If
the manual reset should open due to high temperature, the
gas valves will close and unit will go into lockout. If lockout
occurs, push the SELECTION button on UIM to restart boiler.
ON/OFF SWITCH
The ON/OFF Switch is a single-pole, single-throw rocker switch.
This switch provides 120V from the line source to the boiler.
CIRCULATING PUMP
HOT WATER SUPPLY BOILER-VW, the circulating pump is
integral to the VW models. This pump has been lubricated
at the factory, and future lubrication should be in accordance
with the motor manufacturer’s instructions provided as a
supplement to this manual.
HOT WATER HEATING BOILERS-VB, the circulating pump is NOT
provided on standard models (optional) and must be obtained and
installedintheeld.
NOTE: If a system pump is to be installed on a VB model,
the maximum rating of pump motor must not exceed 1 hp.
TEMPERATURE PROBES
INLET / REMOTE
TEMPERATURE
PROBE
OUTLET
TEMPERATURE
PROBE
INLET / REMOTE
TEMPERATURE
PROBE
OUTLET TEMPERATURE
PROBE
FIGURE 7. REMOTE PROBE INSTALLATION.
Temperature probes are 3/4 inch male NPT threaded immersion
probes, see Figure 7. Temperature probes have embedded
temperature sensors (thermistors). The boiler’s control system
monitors these sensors to determine water temperature at various
points in the system.
INLET AND OUTLET TEMPERATURE PROBES
All VF boilers have one Inlet and one Outlet Temperature Probe
factory installed in the top of the heat exchanger to monitor the
water temperature entering and leaving the boiler. The Inlet Probe
is a temperature sensor only and has two leads. The Outlet probe
also contains the manual reset high temperature limit switch and
has four leads. The control system displays the Inlet and Outlet
water temperatures sensed from these two probes on the default
Temperatures screen.
REMOTE TEMPERATURE PROBE
All VF boilers are supplied from the factory with a Remote
Temperature Probe. The supplied Remote Temperature Probe
is used to control system water temperature for a single boiler
in a domestic hot water storage tank or in the return line from a
primary/secondary hydronic heating system. Use of the Remote
Temperature Probe allows a boiler to sense the actual water
temperature inside the storage tank or hydronic heating loop.
The boiler will modulate its firing rate in response to the
actual system temperature and load conditions. The control
system displays the temperature sensed from the Remote
Temperature Probe as the “Tank” temperature on the default
Temperatures screen.
QUAD THERMISTOR PROBE
When connecting up to 4 boilers to a single storage tank
or one primary/secondary hydronic heating system the
optional Quad Thermistor Probe should be used. The Quad
Thermistor Probe is a remote temperature probe with four
temperature sensors embedded in one device. The Quad
Thermistor Probe allows up to 4 boilers to sense system
temperature from same point in the system. Use of the
Quad Thermistor Probe will allow each connected boiler to
individually sense actual water temperature in the storage tank
or hydronic heating loop. The temperatures sensed from each
of the four temperature sensor circuits in a Quad Thermistor
Probe are shown as “Tank” temperature on each boiler’s
default Temperatures screen.
NOTE: See the Field Wiring, Remote Temperature Probe
Installation and the Primary System Control sections of this manual
for operating and installation instructions.
LOW WATER CUTOFF (OPTIONAL)
If boiler is installed above radiation level, a Low Water Cutoff
Device must be installed in boiler outlet at time of installation
or, order pre-installed from the factory. If low water detection
is required by authorities having jurisdiction, a low water cutoff
switch should be installed in the boiler outlet water line. The switch
should receive periodic (every six months) inspection to assure
proper operation.
PRESSURE RELIEF VALVE
An ASME rated pressure relief valve is furnished with the boiler.
Neveroperatetheboilerifitisnotlledwithwaterandaproperly
sized pressure relief valve is not installed.
The pressure rating of the relief valve should be equal to or less
than the rated pressure capacity of any component in the system
including the boiler. Should the valve need to be replaced, call
the toll free phone number listed on the back of this manual for
further technical assistance.
Explosion Hazard
Relief Valve must comply with
ASME code.
Properly sized Relief Valve must
be installed.
Can result in overheating and
excessive tank pressure.
Can cause serious injury or death.
A discharge pipe from the relief valve should terminate at an adequate
oordrain.Donotthread,plug,orcaptheendofdrainline.
CAUTION
• Pressure Relief Valve discharge pipe must
terminate at adequate drain.
Water Damage Hazard