U.S. Boiler Company PVG3 Service manual

103997-06 - 1/14
As an ENERGY STAR®Partner, U.S. Boiler Company has determined that the PVG-3, PVG-4, PVG-5, PVG-6 and
PVG-7 meet the ENERGY STAR® guidelines for energy efciency established by the United States Environmental
Protection Agency (EPA).
Price - $5.00
9700609
INSTALLATION, OPERATING AND
SERVICE INSTRUCTIONS FOR
PVG™
Gas - Fired Boiler
For service or repairs to boiler, call your heating contractor. When seeking information on boiler, provide
Boiler Model Number and Serial Number as shown on Rating Label.
Model Number Boiler Serial Number Installation Date
Heating Contractor Phone Number
Address

2
IMPORTANT INFORMATION - READ CAREFULLY
NOTE: The equipment shall be installed in accordance with those installation regulations enforced in the area where the
installation is to be made. These regulations shall be carefully followed in all cases. Authorities having jurisdiction
shall be consulted before installations are made.
All wiring on boilers installed in the USA shall be made in accordance with the National Electrical Code and/or local regulations.
All wiring on boilers installed in Canada shall be made in accordance with the Canadian Electrical Code and/or local regulations.
The following terms are used throughout this manual to bring attention to the presence of hazards of various risk levels,
or to important information concerning product life.
The City of New York requires a Licensed Master Plumber supervise the installation of this product.
The Massachusetts Board of Plumbers and Gas Fitters has approved the PVG™ Series boiler. See the Massachusetts Board of
Plumbers and Gas Fitters website, http://license.reg.state.ma.us/pubLic/pl_products/pb_pre_form.asp for the latest Approval
Code or ask your local Sales Representative.
The Commonwealth of Massachusetts requires this product to be installed by a Licensed Plumber or Gas Fitter.
DANGER
Indicates an imminently hazardous situation
which, if not avoided, will result in death, serious
injury or substantial property damage.
CAUTION
Indicates a potentially hazardous situation which,
if not avoided, may result in moderate or minor
injury or property damage.
WARNING
Indicates a potentially hazardous situation which,
if not avoided, could result in death, serious injury
or substantial property damage.
NOTICE
Indicates special instructions on installation,
operation, or maintenance which are important
but not related to personal injury hazards.
DANGER
DO NOT store or use gasoline or other ammable vapors or liquids in the vicinity of this or any other
appliance.
If you smell gas vapors, NO NOT try to operate any appliance - DO NOT touch any electrical switch or use
any phone in the building. Immediately, call the gas supplier from a remotely located phone. Follow the gas
supplier’s instructions or if the supplier is unavailable, contact the re department.

3
Special Installation Requirements for Massachusetts
A. For all side wall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in whole or
in part for residential purposes and where the side wall exhaust vent termination is less than seven (7) feet above grade, the
following requirements shall be satised:
1. If there is no carbon monoxide detector with an alarm already installed in compliance with the most current edition of
NFPA 720, NFPA 70 and the Massachusetts State Building Code in the residential unit served by the side wall horizontally
vented gas fueled equipment, a battery operated carbon monoxide detector with an alarm shall be installed in compliance
with the most current edition of NFPA 720, NFPA 70 and the Massachusetts State Building Code.
2. In addition to the above requirements, if there is not one already present, a carbon monoxide detector with an alarm
and a battery back-up shall be installed and located in accordance with the installation requirements supplied with the
detector on the oor level where the gas equipment is installed. The carbon monoxide detector with an alarm shall
comply with 527 CMR, ANSI/UL 2034 Standards or CSA 6.19 and the most current edition of NFPA 720. In the event
that the requirements of this subdivision can not be met at the time of the completion of the installation of the equipment,
the installer shall have a period of thirty (30) days to comply with this requirement; provided, however, that during said
thirty (30) day period, a battery operated carbon monoxide detector with an alarm shall be installed in compliance with
the most current edition of NFPA 720, NFPA 70 and the Massachusetts State Building Code. In the event that the side
wall horizontally vented gas fueled equipment is installed in a crawl space or an attic, the carbon monoxide detector
may be installed on the next adjacent habitable oor level. Such detector may be a battery operated carbon monoxide
detector with an alarm and shall be installed in compliance with the most current edition of NFPA 720, NFPA 70 and the
Massachusetts State Building Code.
3. A metal or plastic identication 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”.
4. A nal inspection by the state or local gas inspector of the side wall horizontally vented equipment shall not be performed
until proof is provided that the state or local electrical inspector having jurisdiction has granted a permit for installation of
carbon monoxide detectors and alarms as required above.
B. EXEMPTIONS: The following equipment is exempt from 248 CMR 5.08(2)(a) 1 through 4:
1. The equipment listed in Chapter 10 entitled “Equipment Not Required To Be Vented” in the most current edition of NFPA
54 as adopted by the Board; and
2. Product Approved side wall horizontally vented gas fueled equipment installed in a room or structure separate from the
dwelling, building or structure used in whole or in part for residential purposes.
C. When the manufacturer of Product Approved side wall horizontally vented gas equipment provides a venting system design
or venting system components with the equipment, the instructions for installation of the equipment and the venting system
shall include:
1. A complete parts list for the venting system design or venting system; and
2. Detailed instructions for the installation of the venting system design or the venting system components.
D. When the manufacturer of a Product Approved side wall horizontally vented gas fueled equipment does not provide the parts
for venting ue gases, but identies “special venting systems”, the following shall be satised:
1. The referenced “special venting system” instructions shall be included with the appliance or equipment installation
instructions; and
2. The “special venting systems” shall be Product Approved by the Board, and the instructions for that system shall include a
parts list and detailed installation instructions.
E. A copy of all installation instructions for all Product Approved side wall horizontally vented gas fueled equipment, all venting
instructions, all parts lists for venting instructions, and/or all venting design instructions shall remain with the appliance or
equipment at the completion of the installation.

4
WARNING
This boiler requires regular maintenance and service to operate safely. Follow the instructions contained
in this manual.
Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal
injury or loss of life. Read and understand the entire manual before attempting installation, start-up
operation, or service. Installation and service must be performed only by an experienced, skilled, and
knowledgeable installer or service agency.
This boiler must be properly vented.
This boiler needs fresh air for safe operation and must be installed so there are provisions for adequate
combustion and ventilation air.
The interior of the venting system must be inspected and cleaned before the start of the heating season
and should be inspected periodically throughout the heating season for any obstructions. A clean and
unobstructed venting system is necessary to allow noxious fumes that could cause injury or loss of life
to vent safely and will contribute toward maintaining the boiler’s efciency.
Installation is not complete unless a pressure relief valve is installed into the tapping located on top of
appliance. - See the Water Piping and Trim Section of this manual for details.
This boiler is supplied with safety devices which may cause the boiler to shut down and not re-start
without service. If damage due to frozen pipes is a possibility, the heating system should not be left
unattended in cold weather; or appropriate safeguards and alarms should be installed on the heating
system to prevent damage if the boiler is inoperative.
This boiler contains very hot water under high pressure. Do not unscrew any pipe ttings nor attempt
to disconnect any components of this boiler without positively assuring the water is cool and has no
pressure. Always wear protective clothing and equipment when installing, starting up or servicing this
boiler to prevent scald injuries. Do not rely on the pressure and temperature gauges to determine the
temperature and pressure of the boiler. This boiler contains components which become very hot when
the boiler is operating. Do not touch any components unless they are cool.
Boiler materials of construction, products of combustion and the fuel contain alumina, silica, heavy metals,
carbon monoxide, nitrogen oxides, aldehydes and/or other toxic or harmful substances which can cause
death or serious injury and which are known to the state of California to cause cancer, birth defects and
other reproductive harm. Always use proper safety clothing, respirators and equipment when servicing
or working nearby the appliance.
Failure to follow all instructions in the proper order can cause personal injury or death. Read all instruc-
tions, including all those contained in component manufacturers manuals which are provided with the
boiler before installing, starting up, operating, maintaining or servicing.
Keep boiler area clear and free from combustible materials, gasoline and other ammable vapors or
liquids.
All cover plates, enclosures and guards must be in place at all times.
NOTICE
This boiler has a limited warranty, a copy of which is included with this boiler. It is the responsibility of
the installing contractor to see that all controls are correctly installed and are operating properly when the
installation is complete.

5
TABLE OF CONTENTS
Figure 1: Minimum Clearances to Combustibles
I. Pre-Installation............................... 7
II. Unpack Boiler ................................ 8
III. Venting ........................................... 9
IV. Water Piping and Trim ................. 19
V. Gas Piping.................................... 25
VI. Electrical....................................... 28
VII. Modular Installation ....................33
VIII. System Start-up ............................ 35
IX. Operation..................................... 39
X. Troubleshooting ........................... 43
XI. Service .......................................... 48
XII. Repair Parts.................................. 53
Appendix A - Figures .................... 65
Appendix B - Tables...................... 66

6
Figure 2: Dimensions
PVG CONNECTION SIZES(DIMENSIONS IN INCHES)
Model Supply Return Vent Relief Valve
PVG3
1¼ NPT 1¼ NPT
3
¾ NPT
PVG4 PVG5 PVG6 PVG7 PVG8 4 PVG9
PVG DIMENSIONAL DATA
Model ‘A’
PVG3 11.65 PVG4 14.72 PVG5 17.78 PVG6 20.84 PVG7 23.90 PVG8 26.97 PVG9 30.03

7
WARNING
If you do not follow these instructions exactly,
a re or explosion may result causing property
damage or personal injury.
DANGER
Do not install boiler where gasoline or other
ammable vapors or liquids, or sources of
hydrocarbons (i.e. bleaches, cleaners, chemicals,
sprays, paint removers, fabric softeners, etc.) are
used or stored.
NOTICE
Due to the low water content of the boiler, mis-
sizing of the boiler with regard to the heating
system load will result in excessive boiler cycling
and accelerated component failure. U.S. Boiler
DOES NOT warrant failures caused by mis-sized
boiler applications. DO NOT oversize the boiler to
the system. Modular boiler installations greatly
reduce the likelihood of boiler oversizing.
A.Installation must conform to the requirements of the
authority having jurisdiction. In the absence of such
requirements, installation must conform to the National
Fuel Gas Code, ANSI Z223.1/NFPA 54, and/or Natural
Gas and Propane Installation Code, CAN/CSA B149.1.
Where required by authority having jurisdiction,
installation must conform to Standard for Controls and
Safety Devices for Automatically Fired Boilers, ANSI/
ASME CSD-1.
B. Appliance is design certied for installation on
combustible ooring. Do not install boiler on
carpeting.
C. Provide clearance between boiler jacket and
combustible material in accordance with local re
ordinance. Refer to Figure 1 for minimum listed
clearance from combustible material. Recommended
service clearance is 24 (610 mm) inches from left side,
right side and front. Service clearances may be reduced
to minimum clearances to combustible materials.
D. Install on level oor. For basement installation provide
solid base such as concrete, if oor is not level or if
water may be encountered on oor around boiler. Floor
must be able to support weight of boiler, water and all
additional system components.
I. PRE-INSTALLATION
E. Protect gas ignition system components from water
(dripping, spraying, rain, etc.) during boiler operation
and service (circulator replacement, condensate trap,
control replacement, etc.).
F. Provide combustion and ventilation air in accordance
with the section “Air for Combustion and Ventilation,”
of the National Fuel Gas Code, ANSI Z223.1/NFPA 54,
or Sections 8.2, 8.3 or 8.4 of Natural Gas and Propane
Installation Code, CAN/CSA-B149.1, or applicable
provisions of local building codes.
WARNING
Adequate combustion and ventilation air must
be provided to assure proper combustion.
The following guideline is based on the National Fuel Gas
Code, ANSI Z223.1/NFPA 54.
1. Determine volume of space (boiler room). Rooms
communicating directly with space (through
openings not furnished with doors) are considered
part of space.
Volume [ft³] = Length [ft] x Width [ft] x Height [ft]
2. Determine Total Input of all appliances in space.
Round result to nearest 1,000 Btu per hour (Btuh).
3. Determine type of space. Divide Volume by Total
Input.
a. If result is greater than or equal to 50 ft³ per
1,000 Btuh, space is considered an unconned
space.
b. If result is less than 50 ft³ per 1,000 Btuh, space
is considered a conned space.
4. Determine building type. A building of unusually
tight construction has the following characteristics:
a. Walls and ceiling exposed to outside atmosphere
have a continuous water vapor retarder with a
rating of 1 perm or less with openings gasketed
and sealed, and;
b. Weather-stripping has been added on openable
windows and doors, and;
c. Caulking or sealants applied in joints around
window and door frames, between sill plates and
oors, between wall-ceiling joints, between wall
panels, at plumbing and electrical penetrations,
and at other openings.
5. For boiler located in an unconned space in a
building of other than unusually tight construction,
adequate combustion and ventilation air is normally
provided by fresh air inltration through cracks
around windows and doors.

8
conned space. Use indoor air if two permanent
openings communicate directly with additional
space(s) of sufcient volume such that combined
volume of all spaces meet criteria for unconned
space. Size each opening for minimum free area
of one (1) square inch per 1,000 Btu per hour
input of all equipment in spaces, but not less than
100 square inches.
7. Combustion Air/Ventilation Duct Louvers and
Grilles. Equip outside openings with louvers to
prevent entrance of rain and snow, and screens to
prevent entrance of insects and rodents. Louvers and
grilles must be xed in open position or interlocked
with equipment to open automatically before burner
operation. Screens must not be smaller than ¼ inch
mesh.
Consider the blocking effect of louvers, grilles and
screens when calculating the opening size to provide
the required free area. If free area of louver or grille
is not known, assume wood louvers have 20-25
percent free area and metal louvers and grilles have
60-75 percent free area.
II. UNPACK BOILER
CAUTION
Do not drop boiler. Do not bump boiler jacket
against oor.
A. Move boiler to approximate installed position.
B. Remove all crate fasteners.
C. Lift and remove outside container. Save two of the
wooden slats from the container sleeve for use in Steps
E and F.
D. Remove all boiler hold-down fasteners.
WARNING
Installation of this boiler should be undertaken
only by trained and skilled personnel from a
qualied service agency.
E. Tilt the boiler to its front side or back side and slide a
wooden slat under the three raised feet.
F. Tilt the boiler in the opposite direction and slide
another wooden slat under the three raised feet.
G. Slide the boiler left or right off the skid using the two
wooden slats as runners.
H. Move boiler to its permanent location.
6. For boiler located within unconned space in
building of unusually tight construction or within
conned space, provide outdoor air through two
permanent openings which communicate directly or
by duct with the outdoors or spaces (crawl or attic)
freely communicating with the outdoors. Locate one
opening within twelve (12) inches of top of space.
Locate remaining opening within twelve (12) inches
of bottom of space. Minimum dimension of air
opening is three (3) inches. Size each opening per
following:
a. Direct communication with outdoors. Minimum
free area of one (1) square inch per 4,000 Btu per
hour input of all equipment in space.
b. Vertical ducts. Minimum free area of one (1)
square inch per 4,000 Btu per hour input of all
equipment in space. Duct cross-sectional area
shall be same as opening free area.
c. Horizontal ducts. Minimum free area of one (1)
square inch per 2,000 Btu per hour input of all
equipment in space. Duct cross-sectional area
shall be same as opening free area.
Alternate method for boiler located within
CAUTION
Avoid operating this boiler in an environment where saw dust, loose insulation bers, dry wall dust, etc.
are present. If boiler is operated under these conditions, the burner interior and ports must be cleaned and
inspected daily to insure proper operation.
I. PRE-INSTALLATION (continued)

9
III. VENTING
Table 1: Vent System Options
Table 2: Vent System Components Included with Boiler
WARNING
Do not use this boiler with galvanized, Type 304 or Type 316 stainless steel, non metallic or any other
non AL29-4C®based vent systems.
Do not use a barometric damper or draft hood with this appliance.
Do not use vent dampers with this boiler.
Moisture and ice may form on surfaces around termination. To prevent deterioration, surfaces should
be in good repair (sealed, painted, etc.).
This appliance needs fresh air for safe operation and must be installed so there are provisions for
adequate combustion and ventilation air.
Read, understand and follow combustion air instruction restrictions contained in the Pre-Installation
instructions of this manual.
Do not operate appliance where gasoline or other ammable vapors or liquids, or sources of hydro-
carbons (i.e. bleaches, cleaners, chemicals, sprays, paint removers, fabric softeners, etc.) are used,
stored and/or present in the air.
When installing vent pipe through chimney, no other appliance can be vented into the chimney.
Do not exceed maximum vent lengths. Refer to Table 4.
Failure to install a condensate drain line could cause boiler to shutdown unexpectedly.
Option Description
Additional
Vent Kit
Required
Installation
Drawing and
Specication
(See Section)
1. Horizontal Power Vent (air from within building) the vent pipe terminates
horizontally (through a sidewall). 45° Elbow D.
2. Vertical Power Vent (air from within building) the vent pipe terminates
vertically (through the roof). No E.
3. Horizontal Power Vent (air from within building) the vent pipe terminates
horizontally (snorkel through a side wall) 45° Elbow F.
Gasketed Vent System Components Part Number
Vent Terminal 3” - Horizontal PVG3 thru PVG6) 8110701
Vent Terminal 3” - Horizontal (PVG7) 8116310
Vent Terminal 4” - Horizontal (PVG8 & PVG9) 8116313

10
Table 3: Vent System Components
Vent System Component Part
Number
Equivalent
Feet of Pipe
3” Dia. Pipe x 1 Ft 8116296U 1
4” Dia. Pipe x 1 Ft 100176-01
3” Dia. Pipe x 3 Ft 8116298U 3
4” Dia. Pipe x 3 Ft 100177-01
3” Dia. Pipe x 5 Ft 8116300U 5
4” Dia. Pipe x 5 Ft 100178-01
3” Dia. Pipe x Adjustable 8116319U Equal to
Installed Length
(1.06 TO 1.64)
4” Dia. Pipe x Adjustable 100179-01
3” Dia. 90° Elbow 8116294U 5
4” Dia. 90° Elbow 100180-01
3” Dia. 45° Elbow 8116292U 5
4” Dia. 45° Elbow 100181-01
3” Dia. Horizontal Drain Tee 8116302U 2
4” Dia. Horizontal Drain Tee 100182-01
3” Dia. Vertical Drain Tee 8116304U 7½
4” Dia. Vertical Drain Tee 100183-01
3” Single Wall Thimble 8116116 ---
4” Single Wall Thimble 100184-01
3” Double Wall Thimble 103877-01 ---
4” Double Wall Thimble 100185-01
Table 4: Vent Length
Model
3” Vent Pipe
(Equiv. Ft.)
4” Vent Pipe
(Equiv. Ft.)
Min. Max. Min. Max.
PVG3 & PVG4
8 50 --- ---PVG5 & PVG6
PVG7
PVG8 & PVG9 --- --- 8 40
III. VENTING (continued)
A. Vent Guidelines Due to Removal of an Existing
Boiler
IF AN EXISTING BOILER IS REMOVED -
When an existing boiler is removed from a common
venting system, the common venting system is likely
to be too large for proper venting of the appliances
remaining connected to it.
At the time of removal of an existing boiler,
the following steps shall be followed with each
appliance remaining connected to the common
venting system placed in operation, while the other
appliances remaining connected to the common
venting system are not in operation:
1. Seal any unused openings in the common venting
system.
2. Visually inspect the venting system for proper
size and horizontal pitch and determine there is no
blockage or restriction, leakage, corrosion, and other
deciencies which could cause an unsafe condition.
3. Insofar as is practical, close all building doors and
windows and all doors between the space in which
the appliances remaining connected to the common
venting system are located and other spaces of the
building. Turn on clothes dryers and any appliance
not connected to the common venting system.
Turn on any exhaust fans, such as range hoods and
bathroom exhausts, so they will operate at maximum
speed. Do not operate a summer exhaust fan. Close
replace dampers.
4. Place in operation the appliance being inspected.
Follow the Lighting (or Operating) Instructions.
Adjust thermostat so appliance will operate
continuously.
5. Test for spillage at the draft hood relief opening after
5 minutes of main burner operation. Use the ame
of a match or candle, or smoke from a cigarette,
cigar or pipe.
6. After it has been determined that each appliance
remaining connected to the common venting system
properly vents when tested as outlined above, return
doors, win dows, exhaust fans, replace dampers and
any other gas burning appliance to their previous
conditions of use.
7. Any improper operation of the common venting
system should be corrected so the installation
conforms with the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 and/or the Natural Gas and
Propane Installation Code, CAN/CSA B149.1.
When resizing any portion of the common venting
system, the common venting system should be
resized to approach the minimum size as determined
using the appropriate tables in Chapter 13 of the
National Fuel Gas Code, ANSI Z223.1/NFPA 54
and/or the Natural Gas and Propane Installation
Code, CAN/CSA B149.1

11
B. General Guidelines
1. Vent system installation must be in accordance
with National Fuel Gas Code, ANSI Z223.1/NFPA
54, Natural Gas and Propane Installation Code,
CAN/CSA B149.1 or applicable provisions of
local building codes. Contact local building or re
ofcials about restrictions and installation inspection
in your area.
2. This appliance requires a Special Gas Vent.
a. The product is designed to use U.S. Boiler
supplied AL29-4C® Stainless Steel vent system
components. See Table 3 for complete list of
U.S. Boiler Vent System Components.
b. The following manufacturers offer similar AL29-
4C®components and are approved for use with
this product.
• Heat-Fab Inc. - Saf-T-Vent (800-772-0739);
• Flex-L International Inc. - Star-34 (800-561-
1980);
• Z-Flex U. S., Inc. - Z-Vent (800-654-5600);
• Protech Systems, Inc.- FasNSeal™ (800-
766-3473).
The use of these alternate manufacturer’s
venting systems will require adapters to connect
to the U.S. Boiler supplied vent connector and
vent terminal. These adapters are not supplied
with this unit and should be obtained from the
supplier of the alternate manufacturer’s venting
system.
c. Once a vent pipe manufacturer and system is
chosen never mix and match vent systems.
d. Do not use cellular core PVC (ASTM
F891), cellular core CPVC, or Radel®
(polyphenolsulfone).
e. Do not cover non-metallic vent pipe and ttings
with thermal insulation. Note: Non-metallic
vent cannot be used with this boiler.
3. Install venting system in accordance with these
instructions. Refer to the appropriate drawings in
this section of this manual to determine the proper
conguration of venting system. See Table 1.
4. Position venting system to prevent accumulation of
condensate. Slope horizontal portions of vent pipe
upwards not less than 1/4 in/ft (21 mm/m) from
boiler to vent terminal.
les chaudiêres de catégories I doivent présenter
des tronçons horizontaux dont la pente montante
est d’au moins 1/4 po par pied (21 mm/m) entre la
chaudiêre et l’évent.
5. Use noncombustible ¾ inch pipe strap to support
horizontal runs and maintain vent location and
slope while preventing sags in pipe. Do not restrict
thermal expansion or movement of vent system.
III. VENTING (continued)
Au moment du retrait d’une chaudière existante,
les mesures suivantes doivent être prises pour
chaque appareil toujours raccordé au système
d’evacuation commun et qui fonctionne alors que
d’autres appareils toujours raccordés au système
d’évacuation ne fonctionnent pas:
1. Sceller toutes les ouvertures non utilisées du
système d’évacuation.
2. Inspecter de façon visuelle le système d’évacuation
pour déterminer la grosseur et l’inclinaison
horizontale qui conviennent et s’assurer que le
système est exempt d’obstruction, d’étranglement,
de fuite, de corrosion et autres défaillances qui
pourraient présenter des risques.
3. Dans la mesure du possible, fermer toutes les
portes et les fenêtres du bâtiment et toutes les
portes entre l’espace où les appareils toujours
raccordés au système d’évacuation sont installés
et les autres espaces du bâtiment. Mettre en
marche les sécheuses, tous les appareils non
raccordés au système d’évacuation commun
et tous les ventilateurs d’extraction comme les
hottes de cuisinière et les ventilateurs des salles de
bain. S’assurer que ces ventilateurs fonctionnent
à la vitesse maximale. Ne pas faire fonctionner
les ventilateurs d’été. Fermer les registres des
cheminées.
4. Mettre l’appareil inspecté en marche. Suivre les
instructions d’allumage. Régler le thermostat de
façon que l’appareil fonctionne de façon continue.
5. Faire fonctionner le brûleur principal pendant 5
min ensuite, déterminer si le coupe-tirage déborde
à l’ouverture de décharge. Utiliser la amme d’une
allumette ou d’une chandelle ou la fumée d’une
cigarette, d’un cigare ou d’une pipe.
6. Une fois qu’il a été déterminé, selon la méthode
indiquée ci-dessus, que chaque appareil raccordé
au système d’évacuation est mis à l’air libre de
façon adéquate. Remettre les portes et les fenêtres,
les ventilateurs, les registres de cheminées et les
appareils au gaz à leur position originale.
7. Tout mauvais fonctionnement du système
d’évacuation commun devrait être corrigé de
façon que l’installation soit conforme au National
Fuel Gas Code, ANSI Z223.1/NFPA 54 et (ou)
aux codes d’installation CAN/CSA-B149.1. Si la
grosseur d’une section du système d’évacuation
doit être modiée, le système devrait être modié
pour respecter les valeurs minimales des tableaux
pertinents de l’appendice F du National Fuel Gas
Code, ANSI Z223.1/NFPA 54 et (ou) des codes
d’installation CAN/CSA-B149.1.

12
g. Minimum 10 feet (2 m) horizontally from an
operable opening in an adjacent building. This
does not apply to vent terminals 2 feet (0.6 m)
or more above or 25 feet (7.6 m) or more below
operable openings.
9. Enclose vent passing through occupied or
unoccupied spaces above the boiler with material
having a re resistance rating of at least equal to the
rating of the adjoining oor or ceiling. Maintain
minimum clearances to combustible materials. See
Figure 1.
Note: For one or two family dwellings, re
resistance rating requirement may not need to be
met, but is recommended.
10. Plan venting system to avoid possible contact with
plumbing or electrical wires. Start at vent connector
on top of boiler and work towards vent terminal.
11. If a non-standard length pipe is required:
Gasketed Vent System: The use of the adjustable
length pipe (P/N 8116319U) is recommended to
complete a non-standard pipe length. This pipe
requires a minimum installed length of 12¾ inch
and can adjust across a 7 inch gap up to a maximum
of 19¾ inch long. (Note for the adjustable pipe
the installed length should be measured from the
centerline of the bead on the male end of the rst
pipe to the end of the female pipe excluding the
locking band of the second pipe with a single
gasket.) Only in the event the adjustable length pipe
is not sufcient a standard length pipe may be cut
using the procedure outlined below for the Gasket-
Less Vent System.
12.Vent connectors serving appliances vented by
natural draft shall not be connected into any portion
of mechanical draft systems operating under positive
pressure.
WARNING
Never exceed maximum installed length of 19¾
inches for adjustable length pipe.
Risk of ue gas leakage is possible.
NOTICE
Cut must be square with pipe and led or
sanded smooth before joining. Carefully ensure
roundness of cut pipe by hand with gloves before
installing. Seal joint with RTV specied in this
manual.
III. VENTING (continued)
Maximum support spacing is ve (5) feet (1.5 m).
Do not penetrate any part of the vent system with
fasteners.
Soutenez parties horizontales de ventilation pour
éviter l’affaisement. Utilisez des colliers de serrage,
des crochets on cintres espacées de 5 preds (1.5 m)
ou moins.
6. Vent length restrictions are based on equivalent
length of vent pipe (total length of straight pipe
plus equivalent length of ttings). Maximum
vent lengths are listed in Table 4. Do not exceed
maximum vent lengths. Table 3 lists equivalent
lengths for ttings. Do not include vent terminals in
equivalent feet calculations.
7. Provide and maintain vent pipe minimum clearances
to combustible materials. Vent pipe minimum
clearance to combustible material is four (4) inches
(102 mm) when vent is installed in a fully enclosed
(chase) application or three (3) inches (76 mm)
when vent is installed with at least one side open,
similar to a joist bay application. Use double wall
thimble [U.S. Boiler Part No. 103877-01 (3”),
100185-01 (4”)] when penetrating a combustible
wall.
8. Do not install venting system components on
the exterior of the building except as specically
required by these instructions. The vent termination
location is restricted as follows:
a. Bottom of vent terminal at least twelve (12)
inches (300 mm) above grade plus normally
expected snow accumulation level.
b. Minimum three (3) feet (0.3 m) above any forced
air inlet located within ten (10) feet (3 m).
c. Minimum four (4) feet (1.2 m) below, four (4)
feet (1.2 m) horizontally from, or 1 foot (300
mm) above any door, operable window, or
gravity air inlet into any building.
d. Minimum clearance from electric meters, gas
meters, regulators, and relief equipment.
United States. Minimum 4 ft (1.22 m)
horizontally from and in no case above or below,
unless a 4 ft (1.22 m) horizontal distance is
maintained.
Canada. Minimum 6 ft (1.83 m) horizontally
from and in no case above or below, unless a 6 ft
(1.83 m) horizontal distance is maintained.
e. Minimum twelve (12) inches from overhang or
corner of building.
f. Do not terminate over public walkways or over
an area where condensate or vapor could create
nuisance or hazard or could be detrimental to the
operation of regulators, relief valves, or other
equipment.

13
C. Install Vent Pipe, U.S. Boiler Gasketed Vent System.
1. Procedure for Joining U.S. Boiler Gasketed Vent
Pipe and Fittings. See Figure 3.
a. Wipe the male end of each joint using an alcohol
pad to remove any dirt and grease.
b. Align weld seams in pipes and use a slight
twisting motion to FULLY insert male end into
female end of joint. Ensure bead in male end
of pipe is below locking band and rest against
the end of the female pipe. Verify the factory-
installed gasket is not dislodged or cut.
c. Tighten locking band by HAND with a 5/16”
nut driver until snug plus ¼ turn. DO NOT
SECURE JOINTS WITH SHEET METAL
SCREWS OR POP RIVETS. DO NOT
PUNCTURE THE VENT SYSTEM!
d. Once the installation is complete, operate
appliance and inspect all joints to ensure that ue
gases and/or liquid condensate will not escape.
D. Separate Horizontal Venting System. See Figures 4A,
4B and 5. See Figure 28 for Blower Vent Connector
Assembly.
Vent Piping –
1. This boiler is supplied with components as standard
equipment for installation of the separate horizontal
venting system.
Figure 3: U.S. Boiler Gasketed Vent Joint Detail
III. VENTING (continued)
2. Do not exceed maximum vent lengths. Refer to
Table 4.
3. Recommended horizontal installation consists
of vent being sloped down ¼ inch per foot away
from boiler. See Figure 4A. See Figure 4B for an
alternate horizontal installation.
4. Use appropriate designed thimbles when passing
through combustible walls (thimble use optional for
noncombustible walls). Insert thimble through wall
from outside. Secure outside ange to wall with
nails or screws, and seal ID, OD and vent holes with
sealant material. Install inside ange to inside wall,
secure with nails or screws, and seal with sealant
material.
5. For noncombustible wall application when thimble
is not used, size opening such that bell with locking
band attached cannot pass through.
6. Join vent terminal to vent pipe. See Figure 5.
7. Insert vent pipe through thimble/opening from
outside and join to vent system. Apply sealant
between vent pipe and opening/thimble to provide
weathertight seal and prevent entry of combustion
products into building.

14
Figure 4: Horizontal – Vent Installation
III. VENTING (continued)

15
Figure 5: Horizontal – Vent Terminal
Conguration (3” or 4” Vent)
Vertical Venting –
1. See Figure 28 for Blower Vent Connector
Assembly. Do not exceed maximum vent lengths.
Refer to Table 4.
2. Installation of a vertical vent drain tee 8116304U
is required on all vertical vent applications. See
Figures 6 and 7. Attach vertical vent drain tee
directly to elbow or horizontal pipe from an elbow
immediately after vent connector.
E. Separate Vertical Venting System - See
Figures 6, 7, 8 and 9
NOTICE
Roof penetrations require the use of roof ashing
and storm collar - not supplied with boiler.
3. Slope horizontal runs minimum ¼ inch per foot.
Slope towards vertical vent drain tee. Position weld
seams in vent pipes, in all horizontal runs, at the top
to avoid condensate from lying on the seams.
4. Install re stops where vent passes through oors,
ceilings or framed walls. The re stop must close
the opening between the vent pipe and the structure.
5. Whenever possible, install vent straight through
the roof. Refer to Figure 7 if offset is necessary.
Maintain minimum clearance to combustible
materials.
6. Install Vent Terminal.
a. Size roof opening to maintain minimum
clearance from combustible materials.
b. Extend vent pipe to maintain minimum vertical
and horizontal distance of twelve (12) inches
from roof surface. Allow additional vertical
distance for expected snow accumulation.
Provide brace as required. Refer to Figure 8.
c. Install storm collar on vent pipe immediately
above ashing. Apply Dow Corning Silastic 732
RTV Sealant between vent pipe and storm collar
to provide weathertight seal.
d. Attach vent terminal.
III. VENTING (continued)

16
Figure 7: Attic OffsetFigure 6: Vertical Vent Installation
III. VENTING (continued)

17
Figure 8: Vertical Vent Termination
United States: Extend Vent Piping to maintain minimum vertical (“X”) and minimum horizontal (“Y”) distance of twelve (12) inches from roof surface. Allow additional vertical (“X”) distance for expected snow accumulation. Canada: Extend at least 18 inch (450 mm) above highest point where it passes through roof surface and same distance above any other obstruction within horizontal distance of 18 inches (450 mm).
III. VENTING (continued)

18
1. See Figure 28 for Blower Vent Connector Assembly.
Do not exceed maximum vent lengths. Refer to
Table 4.
2. This installation will allow a maximum of seven
(7) feet vertical exterior run of the vent piping to be
installed .
NOTICE
Exterior run to be included in equivalent vent
lengths.
F. Optional Exterior Separate Horizontal Vent Terminal Mounting – See Figure 9.
Figure 9: Horizontal Vent Terminal Installation [3” Vent (left view) or 4” Vent (right view)]
III. VENTING (continued)
3. Install vent piping.
a. Install vent piping for desired venting system.
Refer to specic section for details for vent pipe
installation.
b. After penetrating wall/thimble, install an
AL29-4C®90° elbow so that elbow leg is in the
up direction.
c. Install maximum of seven (7) feet of AL29-4C®
vent pipe. Refer to Sections C through E for
proper procedures for joining vent pipe and ttings.
d. Install AL29-4C®45° elbow to upper AL29-4C®
90° elbow so that leg of 45° is in down direction
(see Figure 9).
f. Install vent terminal.
g. Brace piping if required.

19
A. Design and install boiler and system piping to
prevent oxygen contamination of boiler water and
frequent water additions.
1. There are many possible causes of oxygen
contamination such as:
a. Addition of excessive make-up water as a result
of system leaks.
b. Absorption through open tanks and ttings.
c. Oxygen permeable materials in the distribution
system.
2. In order to insure long product life, oxygen sources
must be eliminated. This can be accomplished by
taking the following measures:
a. Repairing system leaks to eliminate the need for
addition of make-up water.
b. Eliminating open tanks from the system.
c. Eliminating and/or repairing ttings which allow
oxygen absorption.
d. Use of non-permeable materials in the
distribution system.
e. Isolating the boiler from the system water by
installing a heat exchanger.
f. Use properly designed and operating air
elimination devices in water piping.
IV. WATER PIPING AND TRIM
B. Optional Probe LWCO Installation
WARNING
DO NOT ATTEMPT to cut factory wires to
install an aftermarket Low Water Cut Off
(LWCO). Only use connections specically
identied for Low Water Cut Off.
In all cases, follow the Low Water Cut Off
(LWCO) manufacturer’s instructions.
WARNING
Failure to properly pipe boiler may result in improper operation and damage to boiler or structure.
Oxygen contamination of boiler water will cause corrosion of iron and steel boiler components, and
can lead to boiler failure. U.S. Boiler’s Standard Warranty does not cover problems caused by oxygen
contamination of boiler water or scale (lime) build-up caused by frequent addition of water.
1. A low water cutoff is required to protect
a gas-red hot water boiler when any
connected heat distributor (radiation) is
installed below the top of the hot water
boiler (i.e. baseboard on the same oor
level as the boiler). In addition, some
jurisdictions require the use of a LWCO
with a hot water boiler as a redundant safety
control.
It is recommended that the LWCO control
is installed above the boiler to provide
the highest level of protection. However,
where the LWCO control is approved by the
LWCO control manufacturer for installation
in a high boiler tapping of a water boiler, the
use of the listed LWCO control is permitted
when it is installed according to the LWCO
manufacturer’s instructions.
2. The recommended location for a LWCO on
gas hot water boilers is above the boiler, in
the supply piping. The minimum safe water
level of a water boiler is at the uppermost
top of the boiler; that is, it must be full of
water to operate safely.
3. Typically, in residential applications, a probe
type LWCO is used instead of a oat type,
due to their relative costs and the simplicity
of piping for a probe LWCO.
4. Piping and ttings required to install LWCO
are eld supplied.
Figure 10: Recommended Probe LWCO Location

20
5. When constructing a piping tree to install LWCO
select ttings (tees, elbows etc) and nipples to have
the same size (NPT) as boiler supply connection.
At minimum, 1-1/4” tee with ¾” branch outlet is
required to connect the probe LWCO to the supply
piping. See Figure 10. DO NOT REDUCE THE
SIZE OF NEAR BOILER SUPPLY FITTINGS
AND NIPPLES.
6. Installation of manual shutoff valve located above
the LWCO and the boiler is recommended to allow
servicing. Thus LWCO probe can be removed for
inspection without draining the heating system. An
annual inspection of the probe is recommended.
7. The presence of water covering properly installed
LWCO probe will cause the normally open contact
of the LWCO to close, thus providing continuity of
the 24 VAC service to the boiler gas valve. When
water level drops below probe, LWCO contact
opens up breaking 24V supply to gas valve and
preventing the boiler to re.
8. 2012 compliant PVG gas hot water boilers have
a “plug-in” provision in factory wiring that will
accept optional 24VAC probe LWCO harness
connector. The optional LWCO kit (P/N 104083-
01) includes 24VAC probe LWCO, Harness and
Instructions addressing piping, wiring and testing
after installation.
C. Optional Auxiliary Limit Installation
1. Some jurisdictions may require the use of an
Auxiliary Limit control with a hot water boiler as a
redundant safety control.
IV. WATER PIPING AND TRIM (continued)
Figure 11: Recommended Auxiliary Limit Location
2. The recommended location for an Auxiliary Limit
on gas hot water boilers is in the supply piping. See
Figure 11 for recommended location.
3. Piping and ttings required to install an Auxiliary
Limit are eld supplied.
4. When constructing a piping tree to install an
Auxiliary Limit select ttings (tees, elbows etc)
and nipples to have the same size (NPT) as boiler
supply connection. At minimum, 1-1/4” tee with
1/2” branch outlet is required to install the limit
well into the supply piping. See Figure 11. DO
NOT REDUCE THE SIZE OF NEAR BOILER
SUPPLY FITTINGS AND NIPPLES.
5. When boiler water temperature reaches or exceeds
Auxiliary Limit setting, the limit normally closed
contact will open, thus interrupting the 24 VAC
service to the boiler gas valve. When boiler water
temperature drops below limit differential, limit
contact closes restoring 24V supply to gas valve and
allowing the boiler to re.
6. Gas hot water boilers equipped with Intelligent
Hydronic Control have a “plug-in” provision in
factory wiring that will accept optional 24VAC
Auxiliary Limit harness connector. The optional
Auxiliary Limit kit (P/N 103696-01) includes
24VAC Auxiliary Limit, Well, Harness and
Instructions addressing wiring and testing after
installation.
D. Connect system supply and return piping to boiler.
See Figures 14 and 15. Maintain minimum ½ inch
(13 mm) clearance from hot water piping to
combustible materials.