U.S. Boiler Company X-PV Series Service manual

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X-PV • Water Boiler
• Cast Iron
• Induced Draft
• Gas Fired
TO THE INSTALLER:
Affix these instructions adjacent to boiler.
Provide model number and serial number when
seeking information and support.
TO THE CONSUMER:
Retain these instructions for future reference.
Contact heating contractor for all issues and support.
Models:
• X-PV3N • X-PV3P
• X-PV4N • X-PV4P
• X-PV5N • X-PV5P
• X-PV6N • X-PV6P
• X-PV7N • X-PV7P
• X-PV8N • X-PV8P
WARNING
Improper installation, adjustment, alteration, service or maintenance can cause property damage, injury, or
loss of life. For assistance or additional information, consult a qualified installer, service agency or the gas
supplier. Read these instructions carefully before installing.
!
Installation, Operating and Service Instructions for
Table of Contents Page
1. Product Description ..................4
2. Specifications .......................5
3. Pre-Installation ......................6
4. Locating the Boiler ...................7
5. Air for Combustion and Ventilation ......8
6. Venting ............................11
7. Water Piping .......................22
8. Gas Piping .........................26
9. Wiring ............................28
10. Start-Up and Checkout ...............32
11. Operation ..........................36
12. Service and Maintenance ............44
13. Troubleshooting ....................49
14. Service Parts .......................52
Appendix A ........................61
Appendix B ........................66
Appendix C ........................68
Appendix D ........................70
9700609

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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 Massachusetts Board of Plumbers and Gas Fitters has approved these boilers. See the Massachusetts Board of
Plumbers and Gas Fitters website 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.
NOTICE: Indicates special instructions on
installation, operation, or maintenance which
are important but not related to personal injury
hazards.
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, may result in moderate or
minor injury or property damage.
DANGER
Explosion Hazard. DO NOT store or use gasoline or other flammable vapors or liquids in the vicinity of
this or any other appliance.
If you smell gas vapors, DO 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 fire department.
WARNING
This boiler must only be serviced and repaired by skilled and experienced service technicians.
• If any controls are replaced, they must be replaced with identical models.
• Read, understand and follow all the instructions and warnings contained in all the sections of this
manual.
• If any electrical wires are disconnected during service, clearly label the wires and assure that the wires
are reconnected properly.
• Never jump out or bypass any safety or operating control or component of this boiler.
• Assure that all safety and operating controls and components are operating properly before placing
the boiler back in service.
• Annually inspect all vent gaskets and replace any exhibiting damage or deterioration.
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WARNING
Asphyxiation Hazard. Fire Hazard. Explosion Hazard. 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.
• Asphyxiation Hazard. 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.
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 efficiency.
• Installation is not complete unless a safety relief valve is installed in the supply piping. - See the Water
Piping 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.
• Do not obstruct the combustion or ventilation air supply to the boiler.
• Burn Hazard. This boiler contains very hot water under high pressure. Do not unscrew any pipe fittings
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.
• Respiratory Hazard. 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
instructions, including all those contained in component manufacturers manuals which are provided
with the boiler before installing, starting up, operating, maintaining or servicing.
• All cover plates, enclosures and guards must be in place at all times.
DANGER
Explosion Hazard. Electrical Shock Hazard. Burn Hazard. This boiler uses flammable gas, high voltage
electricity, moving parts, and very hot water under high pressure.
Assure that all gas and electric power supplies are off and that the water temperature is cool before
attempting any disassembly or service. Do not attempt any service work if gas is present in the air in the
vicinity of the boiler. Never modify, remove or tamper with any control device.
!
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1Product Description
This is a cast iron gas-fired boiler designed for use in forced hot water heating systems. It is intended for instal-
lations where a usable chimney is not available. This boiler is vented using an approved vertical or horizontal
AL29-4C stainless steel venting system, which is not included with the boiler. This boiler requires an adequate
source of clean combustion air in the boiler room. Alternatively, combustion air may be piped directly from the
outdoors to the boiler using an optional Direct Vent Conversion Kit shown in Table 2.2.
This boiler is not designed for use in gravity or “open” heating systems.

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Figure 2.1: General Configuration
2Specifications
(1) Input ratings can be used for elevations up to 2000 ft above sea level. Refer to Appendix B for elevations 2000 ft or higher.
(2) Net AHRI Water Ratings shown are based on a piping and pickup allowance of 1.15. Consult manufacturer before selecting boiler for
installations having unusual piping and pickup requirements, such as intermittent system operation, extensive piping systems, etc.
X-PV Space Heating Ratings
# of Sections
‘A’
Width
Connection
Size
Water
Content
Approx.
Shipping
Weight
Optional
Direct Vent
Conversion
Kit
Basic
Boiler
Model
Fuel Input (1) Heating
Capacity
Net AHRI
Rating,
Water (2)
AFUE Gas Vent
MBH MBH MBH % (inch) (NPT) (inch) (gal) (lbs) (PN)
X-PV3N NAT. GAS 70 60 52 85.0 3 12-3/4 1/2 3 2 260 110019-03
X-PV4N NAT. GAS 105 90 78 85.0 4 15-1/2 1/2 3 3 310 110019-04
X-PV5N NAT. GAS 140 120 104 85.0 5 18-1/2 1/2 3 4 360 110019-05
X-PV6N NAT. GAS 175 150 130 85.0 6 21-1/2 1/2 3 5 415 110019-06
X-PV7N NAT. GAS 210 179 156 85.0 7 24-3/4 3/4 3 6 470 110019-07
X-PV8N NAT. GAS 245 208 181 84.0 8 27-3/4 3/4 4 7 525 110019-08
X-PV3P PROPANE 63 54 47 85.0 3 12-3/4 1/2 3 2 260 110019-03
X-PV4P PROPANE 94.5 81 70 85.0 4 15-1/2 1/2 3 3 310 110019-04
X-PV5P PROPANE 126 108 94 85.0 5 18-1/2 1/2 3 4 360 110019-05
X-PV6P PROPANE 157.5 135 117 85.0 6 21-1/2 1/2 3 5 415 110019-06
X-PV7P PROPANE 189 161 140 85.0 7 24-3/4 3/4 3 6 470 110019-07
X-PV8P PROPANE 220.5 187 163 84.0 8 27-3/4 3/4 4 7 525 110019-08
Table 2.2: Specifications
Electrical Requirements: 120VAC, 60 Hz, less than 12A
Maximum Allowable Working Pressure - 50 psi. Boiler shipped from factory with a 30 psi safety relief valve.

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3Pre-Installation
WARNING
Carefully read all instructions before installing
boiler. Failure to follow all instructions in proper
order can cause personal injury or death.
A. Inspect shipment carefully for signs of damage.
Any claim for damage or shortage in shipment
must be filed immediately against carrier by
consignee. No claims for variances or shortages
will be allowed by Boiler Manufacturer, unless
presented within sixty (60) days after receipt of
equipment.
B. Safe, reliable operation of this boiler depends
upon installation by a professional heating
contractor in strict accordance with this manual
and the requirements of the authority having
jurisdiction. In absence of such requirements,
installation must conform to National Fuel Gas
Code, ANSI Z223.1/NFPA 54. In Canada, follow
CAN/CSA B149.1 (Natural Gas and Propane
Installation Code). Where required by the
authority having jurisdiction, this installation must
conform to the Standard for Controls and Safety
Devices for Automatically Fired Boilers (ANSI/
ASME CSD-1).
C. Read Section 6 “Venting” to verify that the
maximum exhaust pipe length will not be
exceeded in the planned installation. Also
verify that the vent terminal can be located in
accordance with Section 6.
D. If the boiler is to be direct vented, make sure that
the correct kit shown in Table 2.2 is on hand for
the model boiler being installed. Also consult
Appendix A (Direct Venting) to confirm that the
maximum intake pipe length will not be exceeded
and that the intake terminal may be located as
required on the outside of the building.
E. Make sure that the boiler is correctly sized:
• For heating systems employing convection
radiation (baseboard or radiators), use an
industry accepted sizing method such as
the I=B=R Guide RHH published by the Air-
Conditioning, Heating and Refrigeration Institute
(AHRI).
• For new radiant heating systems, refer to the
radiant tubing manufacturer’s boiler sizing
guidelines.
• For system which includes an indirect water
heater, make sure the boiler has the output
called for by the indirect water heater
manufacturer’s instructions.
!F. Make sure the boiler is configured for the correct
gas (Natural or LP).
G. For high altitude installation above 2,000 ft., see
Appendix B.
H. This boiler is equipped with a listed low water
cut-off (LWCO). Unless the authority having
jurisdiction requires a manual reset LWCO, it
should not be necessary to install an external
LWCO.
NOTICE: This boiler is not approved for use in
Canada above 2000ft.
DANGER
• Do not attempt to operate a natural gas boiler
on LP, or an LP boiler on natural gas without
first converting it using a kit provided by
the factory.
• Failure to properly convert this boiler for
the fuel being used will result in operation
of the boiler at high Carbon Monoxide (CO)
levels and/or other unsafe conditions, resulting
in personal injury or loss of life. Improper
conversion may also result in unreliable
operation and severe property damage.
• Before attempting to operate this boiler at
altitudes above 2000ft, follow the instructions
shown in Appendix B of this manual.
!

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4Locating the Boiler
A. Clearances:
• Provide clearance between boiler jacket
and combustible material in accordance with
local fire ordinances. Observe minimum
clearances shown in Figure 4.1 to avoid
potential fire hazard. Except as noted, these
clearances apply to all combustible
construction as well as noncombustible walls,
ceilings and doors.
Front - 4”
Left Side - 4”
Right Side - 1”
Rear - 1”
Top (Closet installation) - 18”
Top (Alcove installation) - 4"
Note: As an alternate to the side clearances
shown above, the following minimum side
clearances may be used:
Left Side – 1”
Right Side – 4”
WARNING
Failure to observe the following location
requirements could result in a fire, explosion or
carbon monoxide (CO) hazard.
!Note that if this option is exercised, the relief valve
and gauge must still be installed in the location
shown in Figure 4.1. The drain valve on the left
side of the boiler must also remain accessible.
• Provide practical service clearances. A 24”
service clearance from the jacket is
recommended on the left, right, and front
of the boiler. These clearances may be
reduced to those shown in Figure 4.1,
however servicing the boiler will become
increasingly difficult as these service clear-
ances are reduced.
B. Provide a minimum clearance of 1/2" from hot
water pipes to combustible material.
C. Do not install this boiler in a location where
gasoline or other flammable vapors or liquids,
or sources of hydrocarbons (i.e. bleaches,
cleaners, chemicals, sprays, paint removers,
fabric softeners, etc.) are used or stored.
D. Do not install this boiler in an area where large
amounts of airborne dust will be present, such
as a workshop.
E. The boiler must be installed on a hard level
surface. This surface may be combustible.
Figure 4.1: Minimum Clearances To Combustible Construction

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F. Do not install this boiler on carpeting. This may
cause a fire.
G. Do not install this boiler directly on a surface that
may get wet. Raise the boiler on a pad.
H. Protect ignition system components from sources
of water that may spray, drip or rain on them
during installation or service.
I. Install on level floor. For basement installation
provide concrete base if floor is not level or if
water may be encountered on floor around boiler.
5Air for Combustion and Ventilation
Provide provisions for 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 Clause 8.2, 8.3 or 8.4 of Natural
Gas and Propane Installation Code, CAN/CSA B149.1,
or applicable provisions of the local building codes.
In almost all cases, one of the following two
techniques will be best for supplying this boiler with
adequate fresh air:
Indoor Combustion Air – Combustion air is drawn
into the boiler room from other parts of the building
and from outdoors through natural infiltration (cracks
under doors, etc). This method cannot be used in
all cases – see discussion below.
Direct Venting – Combustion air is pulled directly from
outside using the appropriate Direct Vent Conversion
Kit shown in Table 2.2 with installer supplied PVC
or galvanized air intake piping. See Appendix A
for details on installing this boiler with a direct vent
system.
WARNING
PROVIDE ENOUGH AIR to ventilate the boiler
room and sustain combustion. Ignition failure,
overheating, fire, carbon monoxide, and
spillage of flue gases may result from poor air
supply.
!
WARNING
INSUFFICIENT COMBUSTION AIR SUPPLY may
result in the production and release of deadly
carbon monoxide (CO) into the home.
!
WARNING
Do not install this boiler in areas where it
will draw combustion air from areas where
chemicals, such as bleaches, fabric softeners,
paints, cleaners, refrigerants, and cat boxes
are used or stored. Do not draw combustion
air containing large amounts of dust such as
that generated by dry wall construction or
woodworking. Failure to observe this warning
could result in objectionable odors, severe
boiler damage, personal injury or loss of life.
!
NOTICE: If combustion air is being brought
to this boiler using one of the Direct Vent
Conversion Kits shown in Table 2.2, requirements
in Section 5 do not apply: See Appendix A for
combustion and ventilation air requirements.
4Locating the Boiler (continued)

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The National Fuel Gas Code does describe some
other acceptable techniques for bringing outdoor
combustion air to the boiler room, but these should
rarely be needed and are not discussed here.
A. Using the Indoor Combustion Air Method
1) Total the input of all appliances in the boiler
room in thousands of BTU/hr.
2) Find the volume of the boiler room in cubic
feet:
Volume (ft3) = Length (ft) x Width (ft) x Height
(ft)
If the boiler room adjoins another room and
there is no door present between these two
rooms, add the volumes of the rooms to-
gether. Repeat for any other connected rooms
which do not have doors. Do not add the
volume of two rooms separated by a door
even if that door is “always left open”.
3) Divide the volume obtained in Step 2 by the
input calculated in Step 1.
4) If the result is at least 50 ft3per 1000BTU/hr,
and none of the conditions described in (6)
below are met, normal infiltration should pro-
vide adequate fresh air into the boiler room.
5) If the result is less than 50 ft3per 1000BTU/
hr, provide two openings into the boiler room,
one near the floor and one near the ceiling.
The top edge of the upper opening must be
within 6” of the ceiling and the bottom edge
of the lower opening must be within 6” of the
floor (Figure 5.1):
• For rooms that are both on the same floor,
each opening must have a free area of
1 square inch per 1000 BTU/hr input of
all gas burning appliances in the boiler
room.
• For rooms that are not all on the same
floor (such as a boiler room and adjoining
hall with stairway), each opening must
have a free area of 2 square inches per
1000 BTU/hr input of all gas burning
appliances in the boiler.
• The minimum opening dimension is 3
inches. Minimum opening free area is 100
square inches per opening.
• If the total volume of both the boiler room
and the room to which the openings
connect is less than 50 cubic feet per
1000 BTU/hr of total appliance input,
install a pair of identical openings into
a third room. Connect additional rooms
with openings until the total volume of all
rooms is at least 50 cubic feet per 1000
BTU/hr of input. Note that if any of the
connected rooms, is on a different floor,
each of the two openings between all
connected rooms must have a free area of
2 square inches per 1000 BTU/hr of input.
• The “free area” of an opening takes into
account the blocking effect of mesh,
grills, and louvers. Where screens are
used, they must be no finer than ¼” (4 x
4) mesh.
• If providing openings into adjacent
rooms is undesirable, use the Direct Vent
Conversion Kit.
6) Do not use the Indoor Combustion Air Method
described above if any of the following are
true:
a. The indoor space is so tightly con-
structed that the number of air
changes per hour is known to be 0.4
or less.
b. The boiler room is depressurized
relative to the outdoors. This depres-
surization is possible if the structure is
tightly constructed and/or is equipped
with exhaust fans.
c. The building is known to be of
unusually tight construction, which
is defined here as construction having
all of the following characteristics:
• Walls exposed to the outdoor
atmosphere having a continuous
water vapor retarder with a rating of
1 perm or less with openings
gasketed or sealed.
• Openable windows and doors are
weather stripped.
• Caulking or sealants are applied
to areas, such as joints around
window and door frames, between
sole plates and floors, between
wall-ceiling joints, between wall
panels, at penetrations for
plumbing, electrical and gas lines
and at other openings.
5Air for Combustion and Ventilation (continued)

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Example:
A 105000 BTU/hr input boiler and a
water heater are to be installed in a room
measuring 6 ft - 3 in x 7 ft with an 8 ft ceiling.
The water heater has an input of 30000 BTU/
hr:
Total input in thousands of BTU/hr = (105000
BTU/hr + 30000 BTU/hr) ÷ 1000 = 135
Volume of room = 6.25 ft x 7 ft x 8 ft = 350 ft3
350÷135 = 2.59. Since 2.59 is less than 50,
there will be an inadequate fresh air sup-
ply in the boiler room unless openings are
installed between the boiler room and at
least one adjacent room. It turns out that the
boiler room in this example is adjacent to a
full basement which is 20ft x 45ft x 8ft high.
If two openings are installed into this base-
ment that each have a free area of 135in2,
the combined volume of the boiler room and
basement will be:
350ft3+ 6400ft3 = 6750ft3 and:
6750÷135 = 50ft3per 1000 BTU/hr.
In the absence of one of the conditions
described in (6) above, this arrangement
should provide an adequate fresh air supply
to all the appliances in the boiler room.
6” MAX
6” MAX
Figure 5.1: Indoor Combustion Air Method
B. Using Outdoor Combustion Air (“Direct Venting”)
This method requires the Direct Vent Conversion Kit
shown in Table 2.2. Appendix A describes how to size
and run the intake pipe.
Although combustion air is supplied through the air
intake piping, ventilation air is still required around the
boiler to prevent overheating of boiler components.
If the boiler is installed in a closet, provide two
openings in the closet, each having a net free area of
100 square inches as shown in Figure 5.1. Note that
these openings are independent of the boiler size.
Additional area may be required if other fuel burning
appliances are installed in this closet.
5Air for Combustion and Ventilation (continued)

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6Venting
WARNING
Asphyxiation Hazard. Failure to vent this boiler
in accordance with these instructions could
cause products of combustion to enter the
building resulting in severe property damage,
personal injury or death.
Do not vent this boiler with vent systems not
specifically specified in this manual. Prohibited
vent system components include, but are
not limited to:
• CPVC, PVC, Radel® (polyphenolsulfone)
and other Non-metallic pipe.
• Metallic pipe that is not AL29-4C stainless
steel.
Do not attempt to vent this boiler into a masonry
or “B” vent chimney.
Do not use a barometric damper, draft hood or
vent damper with this boiler.
Do not attempt to mix components from different
approved vent systems.
Do not common vent this boiler with any other
appliances.
Do not penetrate vent pipe with holes or
fasteners.
Do not locate vent termination under a deck.
!
A. Vent System Design
There are two basic ways to vent this boiler:
• Horizontal (“side wall”) venting using an
approved AL29-4C stainless steel vent system.
• Vertical venting using an approved AL29-4C
stainless steel vent system.
Table 6.1 summarizes these venting options. One of
the columns in Table 6.1 must describe the planned
vent system exactly. In addition, observe the
following guidelines:
1. Approved Vent Systems - Use only one of the
approved vent systems shown in Table 6.7.
These systems are made of a special stainless
steel alloy (AL29-4C) for protection against
corrosive flue gas condensate. They are also
designed to provide a gas tight seal at all
joints and seams so that flue gas does not
enter the building. Each approved vent
system has unique method for installation - do
not attempt to mix components from different
vent systems.
2. Maximum Vent Lengths
The maximum length of the vent piping
depends upon the vent option selected,
the vent pipe size, and the boiler size.
See Table 6.1 for the maximum vent length.
The maximum allowable vent length must
be reduced by the amount shown in Table
6.8 for each elbow used. Note: Termination
fittings are not counted when counting
additional elbows.
Example:
A 3” vent system is planned for a horizontal
direct vented 105,000 BTU/hr boiler which
has the following components:
2 ft vertical pipe
1 90 elbow
5 ft horizontal pipe
1 90 elbow
3 ft horizontal pipe
1 45 elbow
4 ft horizontal pipe
1 termination tee
The Vent Option #1 column in Table 6.1
describes a horizontal direct exhaust system
using 3” vent pipe. From this column,
we see that this boiler may have a vent
length of up to 50ft. The termination tee
is not considered. From Table 6.8, the
equivalent length of the 3” 45 elbow, is 4ft
and the equivalent length of the 3” 90 degree
elbow, is 5.5ft. The maximum allowable run of
straight pipe on this system is therefore:
50ft – 5.5 ft – 5.5ft - 4.0ft = 35ft
Since the planned installation has only
14 ft of straight pipe, the planned vent length
is acceptable.
3. Permitted Terminals for Horizontal Venting
(Vent Options 1, 2) - Table 6.1 shows
permitted types of terminals.
NOTICE: When this boiler is direct vented,
refer to this section for proper installation of the
venting system. Refer to Appendix A for the
proper design and assembly of the air intake
system.

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Table 6.1: Summary Of Venting Options Using Indoor Combustion Air
(See Appendix A for Options Using Outdoor Air)
Classification Used in this Manual Horizontal Direct Exhaust Vertical Direct Exhaust
Vent Option # 1 2 3 4
Illustrated in Figure 6.2 6.2 6.6 6.6
Structure Penetration Wall Wall Roof Roof
Material Listed AL29-4C Stainless Special Gas Vent System (See Table 6.7)
Nominal Diameter (inches) 3 433 4
Maximum
Vent Length
X-PV3 thru X-PV6 50 ft Not Permitted 50 ft Not Permitted
X-PV7 15 ft 50 ft 15 ft 50 ft
X-PV8 Not Permitted 40 ft Not Permitted 40 ft
Terminal Option A 3" Tee14" Tee13" Cap14" Cap1
Terminal Option B Miter + 45 Elbow2Not Permitted Not Permitted Not Permitted
1. Tee or Cap terminal is supplied by the installer and is compatible with special gas vent system. See Table 6.7 for details.
2. Suitable for use on X-PV3 thru X-PV6 only. Miter terminal is part #8110701 and is purchased separately. 45° Elbow is
by special gas vent manufacturer.
3. The X-PV7 is factory supplied with a 3" adaptor. A 3 x 4 increaser compatible with the special gas vent system is required when this
model is vented using 4" pipe. When used, this increaser must be the first fitting installed on the boiler adaptor.
NOTICE: Do not exceed maximum vent system length. Refer to Table 6.1 in this section for maximum vent
system length. Use only vent terminals and terminal locations shown in Tables 6.1, and 6.6 and related Figures
in this section.
4. Horizontal Vent Terminal Location - Observe
the following limitations on the vent terminal
location (also see Figure 6.9):
• Terminal must be at least 4 feet below
or 4 feet horizontally from any operable
window, door, or gravity air inlet into the
building.
• The bottom of the terminal must be at least
12” above the normal snow line. In no case
should it be less than 12” above grade
level.
• Do not locate the vent terminal over a
public walkway.
• The bottom of the terminal must be at
least 3 feet above any forced air inlet
located within 10 feet.
• 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.
• Do not locate the terminal under decks or
similar structures.
• In general, the top of the vent terminal
must be at least 4ft below eves, soffits,
and other overhangs. If the overhang is
unventilated and if the terminal can extend
beyond the overhang while meeting the
stick-out requirements shown in Figure
6.3 or 6.4, this vertical clearance can be
reduced to as little as 12”. See Figure 6.9c.
Note that flue gas condensate will form
under such overhangs and construction in
this area must be appropriately protected.
• Terminal must be at least 12” from an
inside corner. Exception: if window and/or
air inlet is within four (4) feet of an inside
corner, then vent terminal must be at least
six (6) feet from adjoining wall of inside
corner.
• Under certain conditions, water in the
flue gas may condense on the structure
in areas around the terminal. If these areas
are made of materials subject to damage
from flue gas condensate or ice, they
should be protected.
6A Vent System Design (continued)

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Figure 6.2: Horizontal Direct Exhaust Vent System (Vent Options 1, 2)
Figure 6.3: Tee Terminal Figure 6.4: Optional Miter Terminal
(X-PV3 thru X-PV6 Only)
6A Vent System Design (continued)

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• If possible, install the terminal on a wall
away from the prevailing wind. Reliable
operation of this boiler cannot be
guaranteed if the terminal is subjected to
winds in excess of 40 mph.
• The noise level in the vicinity of the
terminal is approximately 65 dB (roughly
the level of a normal conversation). Avoid
positioning the terminal in areas where this
might be objectionable.
5. Terminal Offsets - Tee terminals may be offset
by as much as 7 ft as shown in Figure 6.5.
This sometimes helps maintain the 12”
minimum clearance required above the
snow line. The extra two elbows and
the section of vertical pipe on the outside
of the building must be counted when
checking that the maximum vent
pipe length is not exceeded. When
this offset is used, the horizontal section of
vent pipe must be pitched away from the
outside so that condensate cannot collect in
the lower offset elbow.
6. Permitted Terminals for Vertical Venting (Vent
Options 3, 4) - Terminals used on these
systems are caps provided by the vent
system manufacturer. Vent manufacturer part
numbers for these caps are shown in Table
6.7.
7. Vertical Vent Terminal Locations (Vent Options
3, 4) - The lowest discharge opening on
the cap must be at least 2 feet above any
object located within 10 feet. (Figure 6.6)
8. Wall Thimbles – Wall thimbles are required
where the vent pipe passes through
combustible walls with less than the required
clearance shown in Figure 4.1 or as required
by local codes. Vent manufacturer’s wall
thimble part numbers are shown in Table 6.7.
9. Condensate Traps and Pitch of Horizontal
Piping – All installations require a condensate
trap. Pitch all horizontal piping ¼” per
foot so that any condensate or rain water in
the vent system will run towards this trap. Vent
manufacturer’s part numbers for suitable traps
are shown in Table 6.7.
10. Fire Stops and Wall Thimbles – Use
fire stops where required by code or by
the vent system manufacturer. Consult vent
system manufacturer’s literature for
information on suitable fire stops.
11. Supports - Vertical and horizontal sections of
vent pipe must be properly supported. See
the Vent System assembly section of this
manual for more information.
12. Access for Inspection - Refer to the vent
manufacturer's instructions for access
requirements to vent components.
Figure 6.5: Optional Terminal Offset for Horizontal Vent Systems
6A Vent System Design (continued)

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Figure 6.6: Vertical Direct Exhaust System (Vent Options 3, 4)
6A Vent System Design (continued)

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Table 6.7: Permissible Vent Systems And Principle Vent Components
MANUFACTURER VENT SYSTEM SIZE CONDENSATE
TRAP
WALL
THIMBLES
HORIZONTAL
TERMINATION
VERTICAL
TERMINATION
HEAT FAB
SAF-T VENT
EZ SEAL
39321
(NOTE 2)
7393GC
7393GCS
5391CI
TEE: 7390TEE 5300CI
49421
(NOTE 2)
7493GC
7493GCS
5491CI
TEE: 7490TEE 5400CI
PROTECH
SYSTEMS
INC.
FASNSEAL
3 FSHDT3 FSWT3 TEE: FSTT3 FSRC3
4
FSHDT4
OR FSCD4
(NOTE 3)
FSWT4 TEE: FSTT4 FSRC4
Z-FLEX
SVE
SERIES III
(“Z-VENT III”)
3 SVEDWCF03 2SVSWTEF03 TEE: 2SVSTTF03 2SVSRCF03
4 SVEDWCF04 2SVSWTEF04 TEE: 2SVSTTF04 2SVSRCF04
METAL-FAB CORR/GUARD
3 CGSWDS(3”) CGSWWPK(3”) TEE: CGSWTTM(3”) CGSWC(3”)
4 CGSWDS(4”) CGSWWPK(4”) TEE: CGSWTTM(4”) CGSWC(4”)
NOTES:
1) See vent system manufacturer’s literature for other part numbers that are required such as straight pipe, elbows, firestops and vent supports.
2) All Heat Fab condensate traps shown may be installed in vertical or horizontal run.
3) Protech FSCD4 condensate trap may be installed in a vertical or horizontal run. All other Protech traps must be installed in a horizontal run
only.
4) Metal-Fab CGSWDS condensate traps may only be installed in a horizontal run.
5) 8110701 Miter terminal may be used as shown in Figure 6.4. 45° elbow is supplied by vent system manufacturer.
Table 6.8: Vent Fitting Equivalent Length
VENT FITTING EQUIVALENT
LENGTH (ft)*
3” 90 ELBOW 5.5
3” 45 ELBOW 4.0
4” 90 ELBOW 8.0
4” 45 ELBOW 4.5
* Where different equivalent lengths are published by the
vent system manufacturer, these may be used in lieu of the
values shown in Table 6.8
6A Vent System Design (continued)

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Figure 6.9a: Location of Vent Terminal Relative to Windows, Doors and Grades
6A Vent System Design (continued)
Figure 6.9b: Location of Vent Terminal Relative to Meters and Forced Air Inlets

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Figure 6.9c: Location of Vent Terminal Under Overhangs
'Y' 'X' Max. Overhang
0 - 12" NOT PERMITTED
12 - 48" 17 - 29" X minus 7"
Greater than 48" 17 - 29" 36"
Note: Overhang may not be ventilated if 'Y' is less than 48"
6A Vent System Design (continued)

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Au moment du retrait d’une chaudière existante,
les mesures suivantes doivent être prises pour
chaque appareil toujours raccordé au système
d’évacuation commun et qui fonctionne alors que
d’autres appareils toujours raccordés au système
d’évacuation ne fonctionnent pas:
a. Sceller toutes les ouvertures non utilisées du
système d’évacuation.
b. Inspecter de façon visuelle le système
d’évcuation 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.
c. 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.
d. Mettre l’appareil inspecté en
marche Suivre les instructions d’allumage.
Régler le thermostat de façon que
l’appareil fonctionne de façon continue.
e. Faire fonctionner le brùleur principal pendant
5 min ensuite, déterminer si le coupe-tirage
déborde à l’ouverture de décharge. Utiliser
la flamme d’une allumette ou d’une chandelle
ou la fumée d’une cigarette, d’un cigare ou
d’une pipe.
B. Removing Boiler From Common Chimney
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:
a. Seal any unused openings in the common
venting system.
b. Visually inspect the venting system for proper
size and horizontal pitch and determine
there is no blockage or restriction, leakage,
corrosion, and other deficiencies which could
cause an unsafe condition.
c. 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 fireplace dampers.
d. Place in operation the appliance being
inspected. Follow the Lighting (or Operating)
Instructions. Adjust thermostat so appliance
will operate continuously.
e. Test for spillage at the draft hood relief opening
after 5 minutes of main burner operation. Use
the flame of a match or candle, or smoke from
a cigarette, cigar or pipe.
f. After it has been determined that each
appliance remaining connected to the common
venting system properly vents when tested as
outlined above, return doors, windows, exhaust
fans, fireplace dampers and any other gas-
burning appliance to their previous condition of
use.
g. 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. 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
WARNING
Never common vent this boiler with other
appliances.
!
of the National Fuel Gas Code, ANSI Z223.1/
NFPA 54 and/or the Natural Gas and Propane
Installation Code, CAN/CSA B149.1.
6B Removing Boiler From Common Chimney

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f. 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.
g. Tout mauvais fonctionnement du système
d’évacuation commun devrat 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 modifiée, le système devrait être
modifié 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. CAUTION
Approved vent systems rely on gaskets for proper
sealing. Take the following precautions:
• Make sure that gasket is in position and
undamaged in the female end of the pipe.
• Make sure that both the male and female pipes
are free of damage prior to assembly.
• After making the vent adapter connection,
only cut vent pipe as permitted by the vent
manufacturer in accordance with their
instructions. When pipe is cut, cut end must be
square and carefully deburred prior to
assembly.
!
Figure 6.10: Installation of Vent Adapter
C. Vent System Assembly
1. General Assembly Notes:
a. Where the use of “silicone” is called for in the
following instructions, use GE RTV 106 for the
vent adapter.
b. Longitudinal welded seams should not be
placed at the bottom of horizontal sections of
exhaust pipe.
c. Do not drill holes in vent pipe.
d. Do not attempt to mix vent components of
different vent system manufacturers.
e. In some cases, there are differences
between the vent system installation
instructions in this manual and those in
the vent system manufacturer’s manual.
Where such differences exist, this manual
takes precedence over the vent system
manufacturer’s manual.
2. Vent Adapter Installation – The vent adapter is
shipped loose. Mount the vent adapter to the
fan outlet on the boiler as shown in Figure 6.10
using the two stainless steel screws provided.
3. Connection of Vent Pipe to Vent Adapter
a. If using Heat Fab Saf-T- Vent, cut the
spigot off of the first piece of pipe using
a sharp pair of aviation snips, an
abrasive cut-off, or a plasma cutter. The male
end of the pipe made by other vent system
manufacturers should slip into the vent
adapter without modification.
b. Remove the hose clamp shipped on the
vent adapter. Bend the three hose clamp
tabs on this adapter outward slightly.
c. Clean the exterior of the male end of the
first piece of pipe and the inside of the vent
adapter on the boiler with an alcohol pad.
6B Removing Boiler From Common Chimney (continued)