Bryan Boilers Forced Draft Steam Boilers User manual

Installation
Operation
Service Manual
for
Forced Draft Steam
Boilers
E-Mail: [email protected] / Internet: www.bryanboilers.com
BRYAN BOILERS
783 N. CHILI AVENUE, PERU, INDIANA 46970
Telephone: [phone] / Fax: [phone]

INSTALLATION INSTRUCTIONS
FORCED DRAFT
STEAM BOILERS
NOTE:
• Please read all of instruction manual before attempting installation.
• Insurance and local or state regulatory codes may contain additional or more stringent requirements
than those contained in this manual. Installation must conform to these codes and any other
authority having jurisdiction.
1.1 BOILER FOUNDATION
Before uncrating, the boiler location should be
prepared. The boiler should set upon a good level
concrete floor. If the boiler is not level or the floor
in good condition, a concrete foundation should
be built, the dimensions larger than the outside
dimensions of the boiler base.
DO NOT INSTALL BOILER ON COMBUSTIBLE
FLOORING. The only exception to this is UL
Labeled F -Series boilers which may be installed
on combustible flooring.
IMPORTANT
If the boiler is installed directly on a concrete floor
where it is important that the floor be kept cool
(such as an upper floor or mezzanine or when
sitting over wiring conduits) set the boiler up on
insulating tile or steel framework so that air may
circulate underneath. For atmospheric gas fired
boilers, it is advisable to build up an insulating
floor under the boiler using high temperature
mineral fiber board at least 1 1/2" thick.
1.2 CLEARANCES
See Table 1 for minimum clearances to wall,
ceilings, or obstructions. The clearances in Table
1 are intended as a general recommendation
only. Local codes must be applied to specific
installations and the minimum clearances
established accordingly. Provisions must also be
made for service, accessibility and clearance for
piping and electrical connections.
Do not obstruct combustion air and ventilation
openings with piping or any other construction. All
boilers must be installed in a space which is
large, compared to the boiler. Only UL Labeled F-
Series boilers are suitable for installation on
combustible flooring.
NOTE
ADHERE TO ALL APPLICABLE LOCAL CODES
REGARDING BOILER INSTALLATION AND
CLEARANCES.
1.3 UNCRATING THE BOILER
Uncrate the boiler near its permanent location.
Leave it on the bottom crating until ready to place
permanently. Leave the plastic shroud on the
boiler until all piping work is complete, cutting
holes in the plastic for access to connections.
Remove the bolts attaching the boiler to the crate
at the underside of the bottom crating. Lift or slide
the boiler off of the bottom crating into position.
Be careful not to tip the boiler up on one corner or
side, which could cause damage to jacket.

MINIMUM CLEARANCES
NOTE: These boilers are intended to be installed in a room which is large compared to the size of
the boiler. They are not intended for alcove installation and are suitable for installation on non-
combustible flooring only.
DIMENSION
D-SERIES F-SERIES1CL-SERIES K-SERIES RV, RW & AB SERIES
WATER/
STEAM
TO 50#
STEAM
OVER
50#
WATER
/STEAM
TO 50#
STEAM
OVER
50#
WATER
/STEAM
TO 50#
STEAM
OVER
50#
WATER
/STEAM
TO 50#
STEAM
OVER
50#
WATER
/STEAM
TO 50#
STEAM
OVER
50#
A 18" 36" 18" 48" 24" 24" 18" 36" 24" 24"
B 24" 24" 48" 96" 48" 36" 48" 24" 48" 48"
CV& CH18" 36" 18" 36" 24" 24" 24" 24" 24" 24"
D 48" 96" 18" 36" 24" 24" 24" 24" 24" 24"
EL& ER24" 24" 18" 36" 24" 24" 24" 24" 32" 32"
1 - F-Series boilers are approved for installation on combustible flooring. Do not install on carpeting.
A - Clearance above boiler
B-Frontofboiler
C
V- Clearance from gas vent, measured vertically above pipe
C
H- Clearance from gas vent, measured horizontally or below pipe
D - From back of boiler
E
L- Left side of boiler
E
R- Right side of boiler
These clearances are general minimum clearances. Local codes may dictate larger clearances.

1.4 BOILER CONNECTIONS
1.4.1 GENERAL
Do not run any pipes along the access panel
side of the boiler. Maintain clearances as
shown on the dimensional drawing for
servicing of the boiler tubes. Provide at least
36" from the gas train and burner, unless a
larger dimension is indicated on the
dimensional. All piping should be designed
and installed to avoid any loadings on the
boiler connections or piping.
1.4.2 STEAM SUPPLY CONNECTION
A steam shut-off valve must be installed
between each boiler and the steam main.
This valve must be of the outside screw and
yoke design to allow indication from a
distance whether the valve is open or closed.
1.4.3 FEEDWATER CONNECTION
Install a check valve and a globe valve
between the feed pump and the boiler. It is
also recommended to install a globe valve
between the feed pump and the receiver
tank. This valve can then be adjusted to
bypass excess pump capacity to better
control the boiler feed rate.
1.4.4 SAFETY RELIEF VALVE(S)
A connection is provided in the top of the
boiler for the relief valve. The relief valve
discharge piping must be the same size as
the relief valve discharge opening. Avoid
over-tightening as this can distort valve seats.
All piping from relief valve must be
independently supported with no weight
carried by the valve.
1.4.4 BLOWDOWN CONNECTION
Blowdown valve(s) must be full size of the
connection on the boiler. Steam boilers 15
psig and below require at least one blowdown
valve. Higher pressure boilers require two
blowdown valves with one or both valves
being slow opening type. Each water column
and float type low water cut-off must be
equipped with a blowdown valve.

1.5 GAS SUPPLY CONNECTION - FORCED DRAFT UNITS
The installation must conform completely to the
requirements of the authority having jurisdiction,
or in the absence of such, requirements shall
conform in the U.S. to the current National Fuel
Gas Code, ANSI Z223.1-1984, or in Canada to
the current Installation Code for Gas Burning
Appliances and Equipment (CAN/CGA B149.1-
M91), or Oil Burning Equipment (CSA B139-
M91), and applicable regional regulations for the
class; which should be followed carefully in all
cases.
Drip leg must be installed on gas supply piping.
Consult the local gas utility company for
inspection and authorization of all gas supply
piping and flue connections.
The regulator vent line must be vented to outside
of building on any boiler equipment with electric
gas pilot ignition.
1.5.1 DRIP LEG
A drip leg or sediment trap must be installed in
the gas supply line. See Fig. 1.5A. The gas line
must be connected to a supply main at least as
large as the gas train connection at the boiler.
This connection should be made with a union so
that the boiler gas train components and burner
may be easily removed, if necessary, for service.
1.5.2 GAS PIPING LEAK TEST
After completion of the gas piping hookup, the
installation must be checked for leaks, using a
soap and water solution. Disconnect the boiler
and gas train from the gas supply piping during
any pressure testing of the gas supply system.
1.5.3 VENTING OF GAS TRAIN COMPONENTS
Gas pressure regulator - The regulator must be
vented to the outside air, using minimum 1/4"
tubing or pipe. The vent line should terminate in a
downward direction to be free of restriction.
Diaphragm gas valves (V48A or V88A) - The vent
line off of these gas valves must be vented to
outdoors, the same as the regulator.
Normally open vent valves - These valves must
be piped to outdoors using pipe no smaller than
that of the valve.
Gas pressure switches - Vent these switches to
outdoors using a minimum of 1/4" tubing or
piping.
FIGURE 1.5A: GAS BURNER CONNECTION
NOTE: USE PIPE COMPOUND, WHICH IS RESISTANT TO THE ACTION OF LIQUID PETROLEUM
GAS. DO NOT USE TEFLON TAPE.

1.6 ELECTRICAL CONNECTION
IMPORTANT: All electrical connections must
conform to the National Electrical Code and to all
other applicable State and Local Codes. Forced
draft boilers may require a high voltage
connection. See boiler wiring diagram and
equipment list for
details.
Equipment Grounding - The boiler must be
grounded in accordance with the American
National Standard Electrical Code, ANSI/NFPA
#70-1981.
1.7 COMBUSTION AIR SUPPLY
IMPORTANT: Positive means for supplying an
ample amount of outside air, allowing complete
combustion of the gas, must be provided.
Movable combustion air dampers, automatic or
manually adjustable, must be electrically
interlocked with the boiler to prevent boiler
operation if the dampers are closed.
Combustion air openings must never be blocked
or obstructed in any manner.
The boiler room must be at a positive or neutral
pressure relative to the outdoors. A negative in
the boiler room will result in downdraft problems
and incomplete combustion due to lack of air.
WARNING!
Failure to provide an adequate air supply will
result in boiler damage and hazardous conditions
in the building (fire and asphyxiation hazard as
well as equipment damage).
COMBUSTION AIR: Complete combustion of
natural or propane gas requires approximately
ten cubic foot of air (at sea level and 70F) for
each 1000 Btu of boiler input. In reality, additional
air is required to achieve complete combustion.
Air is also required for the proper operation of the
appliance draft diverter or barometric damper.
The combustion air opening recommendations
below are designed to provide the air needed for
atmospheric gas fired boilers which are equipped
with either draft diverters or barometric dampers.
Combustion air openings for boilers which are
equipped with forced draft burners may be
reduced to 70% of that required for atmospheric
gas fired boilers. This is because the forced draft
boiler is not equipped with a draft control device
(so no air is required for draft control).
COMBUSTION AIR OPENINGS - AREA
REQUIRED:
Openings directly through outside wall -
One opening within 12 inches of the ceiling plus
one opening within 12 inches of the floor. Each
opening must have a minimum free area of 1
square inch per 4,000 Btu of total input of all air
using appliances in the room.
Example: A boiler room having two boilers with
500,000 Btu input would require two openings
through an outside wall, and each opening must
have at least 250 square inches of free area.
Openings through vertical ducts -
One duct in the ceiling plus one duct terminating
within 12 inches of the floor. Each opening must
have a minimum free area of 1 square inch per
4,000 Btu of total input of all air-using appliances
in the room.
Example: A boiler room having four boilers with
250,000 Btu input would require two ducts, one in
the ceiling and one terminating near the floor,
each opening having at least 250 square inches
of free area.
Openings through horizontal ducts -
One duct opening within 12 inches of the ceiling
plus one duct opening within 12 inches of the
floor. Each opening must have a minimum free
area of 1 square inch of per 2,000 Btu of total
input for all equipment in the room. NOTE: No
rectangular duct may have a dimension of less
than 4 inches.
Example: A boiler room having 1 million Btu total
input would require two ducts, one in the ceiling
and one near the floor, each opening must having
at least 500 square inches of free area.

Ventilation Air: In addition to air needed for
combustion, sufficient air must be supplied for
ventilation, including air required for comfort and
proper working conditions for personnel in the
boiler room. In colder climates, provision should
also be made to heat the boiler room, if
necessary, for personnel comfort.
CAUTION
Protection from combustion air contamination:
Where corrosive or flammable process fumes are
present in the vicinity of the boiler room or the air
stream for the combustion air supply, it is
essential that suitable means be provided for their
safe
disposal. The boiler room and the combustion air
supply must not be exposed to the fumes. Such
fumes include, but are not limited to, carbon
monoxide, hydrogen sulfide, ammonia, chlorine,
and halogenated hydrocarbons.
NOTE: Halogenated hydrocarbons are
particularly injurious and corrosive after exposure
to high temperatures.
1.8 CHIMNEY, FLUE PIPE & DRAFT CONTROL - FORCED DRAFT BOILERS
CODE COMPLIANCE
The installation must conform to the requirements
of NFPA 54, the National Gas Code (ANSI
Z223.1-1984), Part 7, "Venting of Equipment", or
to the applicable requirements of all local building
codes. For factory-built and listed chimney
systems (such as type B vent), consult the
system manufacturer's instructions for correct
installation procedures. Gas vents may be of any
of the construction types listed in this manual. No
portion of a venting system may extend into or
pass through any circulating air duct or plenum.
MINIMUM SAFE PERFORMANCE
Venting systems must be designed to develop
positive flow adequate to remove flue gases to
the outside atmosphere. Guidelines are provided
in this manual and in the National Fuel Gas Code,
NFPA 54, for sizing and design of flue gas
venting systems. For additional reference to good
practice in vent design, refer to the "Chimney,
Gas Vent, and Fireplace Design" chapter of the
ASHRAE Equipment Handbook.
OUTSIDE VENTS AND CHIMNEYS
Outside uninsulated single wall pipe is not
recommended for use in cold climates for venting
gas-fired appliances since temperature
differentials may cause corrosion in such pipe, as
well as poor draft on start ups. When local
experience indicates that condensate may be a
problem, provisions should be made to drain off
the condensate in the gas vent or chimney.
ESTIMATING FLUE GAS FLOW RATE (ACFM)
Flue gas volumetric flow rate in SCFM (standard
cubic feet per minute) and ACFM (actual cubic
feet per minute) can be estimated by using the
information in 1.8.1A. Divide the Total Input of
appliances connected to the chimney or vent by
1000. Then multiply this result times the factor
listed in the SCFM and ACFM table. The ACFM
data is required for determining stack exit velocity
and induced draft fan requirements.
ESTIMATING STACK EXIT VELOCITY
First, determine the ACFM for the stack as
described above. Multiply the total ACFM times
the Velocity Factor from the Velocity Table in
Table 1.8.1B for the stack diameter used. The
result is the Stack Exit Velocity in feet per second.
ESTIMATING STACK EMISSIONS
Table 1.8.1C lists approximate emissions of NOx
(oxides of nitrogen) and CO (carbon monoxide).
The table lists both the concentration, in parts per
million (ppm), and the flow rate, in pounds per
hour (PPH), of each compound: Divide the total
input of appliances connected to the chimney or
vent by 1,000,000. Then multiply this result times
the value listed in the table for PPH emissions.
MANUAL REFERENCES
See Figure 1.8.1 for a graphics listing of
applicable sections of this manual for each
section of the vent system.

FIG. 1.8.1: VENT DESIGN INSTRUCTION -
REFERENCES
TABLE 1.8.1A: ESTIMATING FLUE GAS VOLUMETRIC FLOW RATE
Approximate Flue Gas VOLUMETRIC FLOW RATE
(Per 1000 Btu/hr Input)
(Multiply factor listed times boiler input in MBH)
BOILER TYPE
SCFM Per
1000 Btu/hr
INPUT
ACFM Per
1000 Btu/hr
INPUT
APPROXIMATE
FLUE GAS
TEMPERATURE
Water & 15# Steam
Gas Fired
Oil Fired
0.230
0.230
0.402
0.402
450F
450F
150# Steam
Gas Fired
Oil Fired
0.230
0.230
0.425
0.425
500F
500F
TABLE 1.8.1B: STACK EXIT VELOCITY
Estimated STACK EXIT VELOCITY Calculation
(Multiply total ACFM times the velocity factor below velocity in feet per second)
STACK INSIDE
DIAMETER (Inches)
VELOCITY
FACTOR
STACK INSIDE
DIAMETER (Inches)
VELOCITY
FACTOR
STACK INSIDE
DIAMETER (Inches)
VELOCITY
FACTOR
6
7
8
10
12
14
16
0.0849
0.0624
0.0477
0.0306
0.0212
0.0156
0.0119
18
20
22
24
26
28
32
0.00943
0.00764
0.00631
0.00531
0.00390
0.00340
0.00298
34
36
38
40
48
60
0.00264
0.00236
0.00212
0.00191
0.00133
0.00085

TABLE 1.8.1C: ESTIMATING FLUE GAS EMISSIONS
Estimated Emissions (Volumetric Flow Rate Per Million Btu/hr Input)
(Multiply PPH listed times boiler input divided by 1,000,000)
BOILER
TYPE
PARTICULATES NOx CO SOx Hydrocarbons
PPH per
MMBH
PPM PPH per
MMBH
PPM PPH per
MMBH
PPM PPH per
MMBH
PPM PPH per
MMBH
PPM
Gas Fired
Oil Fired
N/A
0.020
N/A
20
0.049
0.068
50
70
0.194
0.018
200
18
N/A
0.286
N/A
290
0.010
0.004
10
4
1.8.2 CLEARANCES
The vent system and draft control devices must
be installed so as to achieve the clearances to
surfaces outlined in Table 1.2.1, Minimum
Clearances chart, in this manual. See also Table
1.8.9 for vent clearances. All clearances must
comply with the National Fuel Gas Code
(NFPA54), and with all
local and state building codes. The clearances
described in this manual are intended to be
general guidelines only, additional requirements
may occur because of local building design
regulations.
1.8.3 BOILER ROOM PRESSURIZATION
The boiler room must be supplied with adequate
air for combustion and for proper operation of
draft control devices (barometric dampers or draft
diverters) as outlined in "Combustion Air Supply",
Section 1.7 of this manual.
WARNING
THE BOILER ROOM MUST BE MAINTAINED
AT A POSITIVE OR NEUTRAL PRESSURE
(RELATIVE TO OUTDOORS) AT ALL TIMES.
EXHAUST FANS OR CONNECTIONS FROM
THE BOILER ROOM TO ZONES OF NEGATIVE
PRESSURE (AIR DUCTS, NEGATIVE
PRESSURE ROOMS, ETC.) WILL CAUSE
NEGATIVE PRESSURE IN THE BOILER
ROOM. SUCH CONDITIONS WILL CAUSE
HAZARDOUS OPERATION OF THE BOILER
AND INTRODUCTION OF COMBUSTION
PRODUCTS INTO THE BUILDING AIR.
IF THE BOILER ROOM MUST BE UNDER A
NEGATIVE PRESSURE AT ANY TIME, AN
INDUCED DRAFT FAN WILL BE REQUIRED.
FURTHER, THE BOILER MUST BE PROVIDED
WITH A BAROMETRIC DRAFT CONTROL -
NOT WITH A DRAFT DIVERTER. THE FAN
MUST BE INTERLOCKED WITH THE BOILER
AND A DRAFT PROVING SWITCH MUST BE
INSTALLED TO PREVENT OPERATION OF
THE BOILER IF THE FAN SHOULD FAIL TO
OPERATE.
IT ALSO MAY BE ADVISABLE TO INSTALL AN
AUTOMATIC VENT DAMPER IN THE VENT
SYSTEM TO PREVENT BACKFLOW
THROUGH THE VENT SYSTEM DURING
BOILER OFF CYCLES. SEE FOLLOWING
SECTION ON AUTOMATIC VENT DAMPERS.

1.8.7 ACCEPTABLE VENT TYPES
LISTED GAS VENTS
Listed gas vents must be applied only on those
applications for which they are listed. Type B gas
vents are NOT listed for use on forced draft
appliance vent systems.
Installation of these vents must comply with the
vent listing, with the vent manufacturer's
instructions and with complete adherence to the
codes and clearances as outlined previously.
PRESSURIZED VENT SYSTEMS
Some Bryan Boilers (unless specifically fitted for
the application) are not suitable for operation on a
pressurized vent systems. Refer to Section 2 of
this manual for the allowable range of vent
pressure for each series. The RV, RW, and AB
series boilers are designed for pressurized vent
systems. All others require a neutral pressure.
SINGLE-WALL METAL PIPE
Single-wall metal pipe must be of galvanized
sheet or other approved non-combustible
corrosion resistant material, with minimum
thickness per Table 1.8.7, from the National Fuel
Gas Code. Single-wall metal pipe should be
insulated to prevent excessive heat in the boiler
room and to avoid ignition and spillage problems
as well as corrosion from excessive
condensation.
MASONRY, METAL AND FACTORY BUILT
CHIMNEYS
Installation of factory built vents and chimneys
must comply with the vent listing, with the vent
manufacturer's instructions and with adherence to
the codes and clearances as outlined herein.
Masonry or metal chimneys must be built and
installed in accordance with nationally recognized
building codes or standards.
MASONRY CHIMNEYS FOR RESIDENTIAL
APPLICATIONS MUST BE LINED WITH FIRE-
CLAY FLUE LINING (KX C315 OR THE
EQUIVALENT) WITH THICKNESS NOT LESS
THAN 5/16 INCH OR WITH A LINER OF OTHER
APPROVED MATERIAL THAT WILL RESIST
CORROSION, SOFTENING OR CRACKING
FROM FLUE GASES AT TEMPERATURES UP
TO 1800F.
EXISTING CHIMNEYS SHOULD BE
INSPECTED FOR UNSAFE CONDITIONS,
SUCH AS DETERIORATED MASONRY AND
EXCESSIVE SOOT OR OTHER BLOCKAGE OR
POTENTIAL BLOCKAGE. SEE ALSO SECTION
1.8.6.
EXISTING CHIMNEYS MUST BE PROPERLY
SIZED FOR THE FLUE GAS LOADING TO BE
USED. THAT IS, IF AN EXISTING CHIMNEY IS
USED FOR A SMALLER TOTAL INPUT THAN
ITS ORIGINAL DESIGN, A LINER OR VENT IS
REQUIRED. THE USE OF A PROPERLY SIZED
GAS VENT OR LINER WILL PREVENT
DETERIORATION OF THE CHIMNEY DUE TO
THE EXCESSIVE CONDENSATION WHICH
RESULTS ON OVERSIZED SYSTEMS.
WARNING
UNDER NO CIRCUMSTANCES SHOULD THE
FLUE PIPE BE CONNECTED TO THE
CHIMNEY OF AN OPEN FIREPLACE.
TABLE 1.8.7A
WATER BOILER & STEAM BOILERS TO 50 PSIG
TABLE 1.8.7B
(STEAM BOILERS OVER 50 PSIG)
Diameter of
Connector, Inches
Minimum Thickness,
Inch (Gauge)
Diameter of
Connector, Inches
Minimum Thickness,
Inch (Gauge)
6 to 10 0.023 (24) 14 and less 0.053 (16)
10 to 12 0.029 (22) 14 to 16 0.067 (14)
12 to 16 0.034 (20) 16 to 18 0.093 (12)
16 + 0.056 (16) 18 + 0.123 (10)

1.8.5 VENT CONNECTORS (HORIZONTAL RUNS)
CONSTRUCTION
Vent connectors may be of any of the acceptable
constructions listed in this manual.
AVOID UNNECESSARY BENDS
The vent connector must be installed so as to
avoid turns or other construction features which
create excessive resistance to flow of flue gases.
JOINTS
Vent connectors must be firmly attached to draft
diverter outlets or boiler flue collars by sheet metal
screws or other approved means. Vent connectors
of Type B vent material must be assembled in
accordance with the vent manufacturer's
instructions. Joints between sections of connector
piping must be fastened using sheet metal screws
or other approved means.
SLOPE OR VENT CONNECTOR
The vent connector must be installed without any
dips or sags and must slope upward at least 1/4
inch per foot.
LENGTH OF VENT CONNECTOR
The vent connector must be as short as possible
and the boiler as close as practical to the chimney
or vent.
The horizontal run of an uninsulated vent
connector to a natural draft chimney or vent
servicing a single appliance must not be more than
75% of the height of the chimney or vent above
the vent connector.
The horizontal run of an insulated vent connector
to a natural draft chimney or vent servicing a single
appliance must not exceed 100% of the height of
the chimney or vent above the vent connector.
SUPPORT OF VENT CONNECTOR
The vent connector must be supported in
accordance with the vent manufacturer's
instructions and listing and with all applicable
codes. Support should also be independent of the
boiler or the draft diverter (when used). The vent
connector must be supported for the design and
weight of the material employed to maintain
clearances, prevent physical damage and
separation of joints, and to prevent sagging of the
vent connector.
Supports should usually be overhead hangers, of
load bearing capacity appropriate for the weight
involved.
LOCATION
When the vent connector used for an appliance
having a draft hood must be located in or pass
through a crawl space or other area difficult to
access or which may be cold, that portion of the
vent connector must be of listed double wall Type
B gas vent material, or of material having
equivalent insulation qualities. Single wall metal
pipe used as a vent connector must not pass
through any floor or ceiling.
CHIMNEY CONNECTION
In entering a passageway in a masonry or metal
chimney, the vent connector must be installed
above the extreme bottom to avoid stoppage.
Means must be employed which will prevent the
vent connector from protruding so far as to restrict
the space between its end and the opposite wall of
the chimney. A thimble or slip joint may be used to
facilitate removal of the vent connector. The vent
connector must be firmly attached to or inserted
into the thimble or slip joint to prevent the vent
connector from falling out.
DAMPERS
Manually operated dampers must not be placed in
the vent connector. This does not exclude the use
of fixed baffles, locking quadrant dampers which
are welded in a fixed position, or automatic vent
dampers (when properly installed and interlocked
with the boiler gas controls).
USE OF THIMBLES
Vent connectors made of single wall metal pipe
must not pass through any combustible wall
unless they are guarded at the point of passage by
ventilated metal thimbles 6" larger in diameter than
the vent connector. This may be done only on
water boilers and steam boilers rated for operation
at no higher than 50 psig.
SINGLE WALL METAL VENT PIPE USED TO
VENT STEAM BOILERS OPERATING OVER 50
PSIG MUST NOT PASS THROUGH WALLS OR
PARTITIONS CONSTRUCTED OF
COMBUSTIBLE MATERIAL.

1.8.6 CHIMNEY & VENT CONSTRUCTION (VERTICAL SECTION)
INSTALLATION OF FACTORY BUILT
SYSTEMS
Listed gas vents and factory built chimneys must
be installed in accordance with their listings and
the manufacturer's instructions. Vents and
venting systems passing through roofs must
extend though the roof flashing, roof thimble or
roof jack.
INSTALLATION OF MASONRY OR METAL
CHIMNEYS
Masonry or metal chimneys must be built in
accordance with nationally recognized building
codes and standards.
INSTALLATION OF SINGLE WALL GAS VENTS
Single wall metal pipe may be used only for runs
directly from the space in which the appliance is
located through the roof or exterior wall to the
outer air. A pipe passing through a roof must
extend without interruption through the roof
flashing, roof jack or thimble. Single wall metal
pipe must not originate in any unoccupied attic or
concealed space. Additionally, it must not pass
through any attic, inside wall, concealed space or
through any floor. Minimum clearance must be
maintained between the single wall metal pipe
and any combustible surface as outlined in Table
1.8.9.
When a single wall metal pipe passes through an
exterior wall constructed of combustible material,
it must be guarded at the point of passage by a
ventilated thimble as described under "Use of
Thimbles" in Section 1.8.8 of this manual.
Alternatively, a non-ventilating thimble not less
than 18" above and 6" below the roof (with the
annular space open at the bottom and closed at
the top) may be used.
INSPECTIONS OF CHIMNEYS
Before connection of a vent connector to a
chimney, the chimney passageway must be
examined to ascertain that it is clear and free of
obstructions. Cleanouts must be constructed
such that they will remain tightly closed when not
in use. Tee fittings used as cleanouts or
condensate drains must have tight fitting caps to
prevent entrance of air into the chimney at such
points. When an existing masonry chimney is
unlined and local experience indicates that vent
gas condensate may be a problem, an approved
liner or another vent must be installed. When
inspection reveals that an existing chimney is not
safe for the intended application, it must be rebuilt
to conform to nationally recognized standards,
relined with a suitable liner, or replaced with a gas
vent or chimney suitable for the appliances to be
attached.
SUPPORT OF CHIMNEYS AND VENTS
All portions of chimneys must be adequately
supported for the design and weight of the
materials employed. Listed factory built chimneys
must be supported and spaced in accordance
with their listings and the chimney or gas vent
manufacturer's recommendations.
THE GAS VENT OR CHIMNEY MUST BE
SUPPORTED INDEPENDENTLY OF THE
BOILER TOP OR DRAFT DIVERTER.
EQUIPMENT TYPE
MINIMUM REQUIRED DISTANCE FROM COMBUSTIBLE MATERIAL
Listed Vent Single Wall Metal Pipe Factory Built Chimney
Water and 15 psig Steam Boilers not permitted 18" as listed
All Steam Boilers over 15 psig not permitted 36" as listed

1.8.7 MARKING OF GAS VENTS
In those localities where solid and liquid fuels are
used extensively, gas vents must be plainly and
permanently identified by a label reading:
"This gas vent is for appliances which
burn gas only. Do not connect to
incinerators or solid or liquid fuel burning
appliances."
This label must be attached to the wall or ceiling
at a point near where the gas vent connector
enters the wall, ceiling or chimney.
The authority having jurisdiction must determine
whether their area constitutes such a locality.
1.8.8 VENTING MULTIPLE APPLIANCES ON A COMMON VENT
COMMON GAS VENT
When two or more openings (for vent connectors)
are provided in a chimney or gas vent, the
opening should be at different levels. They should
never be opposite one another.
When two vent connectors enter the same gas
vent or chimney, the smallest of the two should
enter at the highest position possible.
PRESSURIZED VENTS OR VENT
CONNECTORS
DO NOT CONNECT THE FLUE OF AN
APPLIANCE VENTED BY NATURAL DRAFT TO
A VENT SYSTEM WHICH OPERATES UNDER
A POSITIVE PRESSURE.
SOLID FUEL APPLIANCE VENTS
Gas appliances must not be vented to a vent or a
chimney which serves a solid fuel burning
appliance.
1.8.9 VENT AND CHIMNEY TERMINATIONS
HEIGHT ABOVE ROOF OR OBSTACLE
WATER BOILERS AND LOW PRESSURE
STEAM BOILERS: No less than 3 feet above the
roof and no less than 2 feet above any parapet or
obstacle closer than 10 feet from the vent outlet.
HIGH PRESSURE (OVER 15 PSIG) STEAM
BOILERS: No less than 10 feet higher than any
portion of any building within a distance of 25 feet
from the vent.
MINIMUM HEIGHT ABOVE DRAFT CONTROL
Chimneys and gas vents must extend at least 5
feet above the highest connected barometric draft
control or any appliance flue outlet.
CLEARANCE FROM AIR INLETS
The vent or chimney must terminate no less than
3 feet above any forced air inlet within a distance
of 10 feet. It must terminate no less than 1 foot
above, or 4 feet below, or 4 feet horizontally from,
any door, window or gravity air inlet into a
building.
CLEARANCE FROM PUBLIC WALKWAYS
The vent exit of a mechanical draft system must
be at least 7 feet above grade when located next
to public walkways.
PROTECTION OF BUILDING MATERIALS
FROM POSSIBLE CORROSION OR
DISCOLORATION FROM FLUE PRODUCTS
The products of combustion from gas or oil
contain potentially corrosive gases and high
temperatures. For this reason, the chimney or
vent exit must be designed to prevent exposure
of the building materials to the flue products.
Failure to do so may result in deterioration or
discoloration of building materials.
VENT SUPPORT
The gas vent or chimney must be securely
positioned and supported. Guy wires or other
reliable means must be used to prevent
movement of the vent.

PROTECTION AGAINST BLOCKAGE OR
OBSTRUCTION
The chimney or vent exit design must prevent any
possibility of blockage by snow or any other
obstruction.
VENTILATING HOODS AND EXHAUST
SYSTEMS
Ventilating hoods or exhaust systems may be
used to vent atmospheric gas appliances. When
these are used, however, such mechanical
exhaust devices must be electrically interlocked
with all appliances on the vent system. The circuit
must prevent the operation of any appliance on
the system if the hood or exhaust system is not in
operation.
STACK CAPS
EVERY GAS VENT MUST BE SUPPLIED WITH
AN APPROVED VENT CAP WHICH WILL
PREVENT THE ENTRANCE OF RAIN OR
OTHER PRECIPITATION INTO THE VENT.
FAILURE TO PROVIDE SUCH A CAP MAY
CAUSE SEVERE BOILER CORROSION,
COMBUSTION PROBLEMS, OR BOTH.
Listed gas vents must be terminated with a listed
cap, approved for use with the particular gas
vent.
Listed vent caps or roof assemblies must have a
rated venting capacity no less than the vent.
Single wall vents must terminate in an approved
cap which does not obstruct the exit. The
preferred type of cap for natural draft vented
atmospheric boilers is the Briedert Cap. This is
because of the protection this cap provides
against wind-generated downdrafts.
Where there is no concern of high winds or
turbulence at the vent exit, a low resistance
conical cap may be used. See Fig. 1.8.12B for
typical dimensions. The diameter of this type cap
should be twice the vent diameter. The cap must
be securely positioned on the vent such as to
provide a clearance of one vent diameter above
the vent exit.
FIG. 1.8.12B: LOW RESISTANCE VENT CAP
1.8.10 AUTOMATIC VENT DAMPERS
ONE APPLIANCE ONLY
An automatic vent must be installed such that it
serves only one appliance vent - that to which it is
properly interlocked.
LISTING REQUIREMENTS
Automatic vent dampers, if used, must be of a
listed type.
INSTALLATION
The damper installation must comply with
Appendix I, J, or K of the National Fuel Gas
Code, NFPA 54. The installation must also
comply with the automatic vent damper listing,
the damper manufacturer's instructions and all
applicable local or state building codes.

AUTOMATIC VENT DAMPERS MUST BE
INSTALLED ONLY BY QUALIFIED SERVICE
TECHNICIANS. FAILURE TO PROPERLY
INSTALL A VENT DAMPER WILL CREATE A
SEVERE HAZARD.
PERFORMANCE TEST
The automatic vent damper must be tested after
installation to assure its proper and safe
operation.
AUTOMATIC VENT DAMPERS MUST BE IN
THE OPEN POSITION AT ANY TIME THE
APPLIANCE MAIN GAS VALVE IS ENERGIZED.
1.8.14 SIZING OF CHIMNEY AND VENT
IMPORTANT
The flue system calculations which follow in
Section 1.8.15 are applicable to double-wall or
insulated single wall breechings (vent connectors)
and stacks (vents). Do not apply these
calculations to uninsulated vent systems.
HIGH ALTITUDES
At altitudes of 2000 feet and higher, atmospheric
boilers must be derated. The amount of derate
required by the National Fuel Gas Code is 4% per
1000 feet above sea level. Boilers which are
shipped from the factory prepared for these
altitudes have the gas orifices properly sized for
this derate. The altitude and gas Btu content for
which the boilers have been constructed is listed
on the Equipment List/Submittal Data in the boiler
manual. The boilers will also be provided with a
label indicating that they have been prepared for
high altitude. If a boiler is to be installed at an
altitude other than that for which it was factory
built, orifices must be replaced to properly adjust
the gas input. Consult the factory or the local
Bryan Representative for the proper parts. For
the purpose of vent system sizing, assume full
input and determine sizing as if at sea level. The
derate factor of 4% per 1000 feet above sea
level accounts for the increased volume per
Btu/hr of flue products at high altitude.
INDUCED DRAFT FANS
Occasionally, the characteristics of an installation
are such that a natural draft vent system will not
suffice. In such cases, induced draft may be
used. The vent system is then sized with an
available "pumping" action equal to the total
theoretical draft plus the static pressure capability
of the induced draft fan. This will result in a
smaller diameter vent than for a natural draft
system. Sizing of induced draft fans should be
done using the recommendations of the fan
manufacturer and the ASHRAE Handbook.
FIG. 1.8.14: SUGGESTED APPLIANCE VENTING PROCEDURE
MULTIPLE APPLIANCE INSTALLATIONS
Bryan recommends that boilers and other gas
appliances be individually vented when possible.
See figure 1.8.14A. Individual venting provides
better draft control and fuel efficiency, and is less
likely to cause condensation in the system. When
individual venting is not possible, boilers may be
vented to a common breeching (vent connector).
See Fig. 1.8.14B for recommended design of
such a system. Note that connections of
individual boiler or appliance vents into the
common breeching should

be done with 45 elbows and not by
"bullheading" directly into the vent connector at
90 angles. "Bullhead" connections generally
cause excessive turbulence and poor draft
conditions. On vent connectors serving multiple
appliances, the diameter of the piping should be
increased at each appliance's entrance so as to
provide a relatively constant flue gas velocity
through the vent system. Using a constant
diameter breeching will often result in poor draft
at the outermost appliances.
1.8.12 QUICK SELECTION FOR VENT SIZING CHARTS
GENERAL
These charts were generated using the
procedure described in Chapter 26 of the
ASHRAE Equipment Handbook (1979). The
results are consistent with those of the National
Fuel Gas Code.
The sizing herein is applicable to vent systems
utilizing double wall listed Type B vent as well as
single wall insulated vent with insulation
equivalent to double wall insulating value.
This sizing procedure is not applicable to vent
systems utilizing single wall uninsulated vents or
vent connectors.
The sizing information given herein is intended as
a general recommendation only. Vent sizing and
installation must comply with local codes.
The responsibility for assurance of such
compliance is that of the system designer and/or
the system installer. All sizing and installation
must be checked against such local
requirements.
RECTANGULAR VENTS
Vent systems may be rectangular as well as
circular. Table 1.8.15F has been provided to give
the circular equivalent of rectangular duct. These
equivalent values account for the higher pressure
drop per cross section area for rectangular ducts.
STEP 1: EQUIVALENT INPUT - DRAFT
CONTROL FACTOR
Determine the boiler (system) Draft Control
Factor, F1, from Table 1.8.15A.
Determine the boiler (or total system) input in
MBH. This is done by dividing the boiler (or total
system) input in Btu/hr by 1000.
Multiply the total input times factor F1.
The equivalent input, I, (without altitude
correction) is then:
I = MBH x F1eq. 15A
TABLE 1.8.15A: DRAFT CONTROL FACTOR F1
Multiply factor time input in MBH
Boiler Type Factor, F1
Atmospheric with Draft Hood 1.000
Atmospheric with Barometric 0.741
Forced Draft Gas or Oil 0.602
STEP 2: EQUIVALENT INPUT - ALTITUDE
FACTOR
Determine the boiler (system) Altitude Correction
Factor, F2, from Table 1.8.15B.
Multiply the boiler (or total system) input times
factors, F2and F1for the equivalent input.
The altitude correction factor, F2for atmospheric
boilers is equal to 1, because their inputs are
already derated for altitude.
The equivalent input, I, with corrections for
altitude is:
I = MBH x F1x F2eq. 15B

Table 1.8.15B ALTITUDE CORRECTION FACTOR, F2
(Multiple factor times sea level input, MBH)
Altitude (ft) Factor, F2Altitude (ft) Factor, F2
0 to 1999
2000
2500
3000
3500
4000
4500
5000
5500
1.00
1.075
1.096
1.116
1.136
1.157
1.180
1.202
1.25
6000
6500
7000
7500
8000
8500
9000
10000
1.247
1.272
1.296
1.322
1.346
1.373
1.399
1.453
STEP 3: SELECT TRIAL DIAMETER
Determine the NET STACK HEIGHT for the vent.
(The net stack height is the vertical distance from
the top of the atmospheric boiler draft control to
the top of the stack. On forced draft boilers it is
the distance from the boiler flue connection to the
top of the stack.)
Find the vent of TRIAL STACK DIAMETER. Enter
Table 1.8.15C at the Net Stack Height column
equal to the system net stack height. Then
proceed down the column to the input which is
just larger than the equivalent to an input which is
just larger than the Equivalent Input of the
system. Read the Trial Stack Diameter in the left
hand column.
NOTE: This is only a trial diameter. Proceed to
Step 4 to calculate the system k-factor to
determine the actual stack diameter required.
STEP 4: CALCULATE SYSTEM K-FACTOR
The system "k-factor" accounts for the pressure
drop through fittings and vent piping. It is
calculated by adding up the individual k-factors
for each of the fittings plus the k-factor for the
vent pipe(s).
From Table 1.8.15D find the k-factors for each of
the elbows, tee fittings, draft regulators, etc. in the
system. Then calculate the vent piping k-factor
from the formula:
k
piping = 0.4 x L/D eq. 15C
L = total length of piping in feet
D = diameter of piping in inches
Add all the k-factors together to determine the
total system k-factor:
k
total = kpiping + kfittings eq. 15D
NOTE: On multiple appliance systems, multiply
the k-factor times 1.5. This is required only on
atmospheric boiler vent systems, not on forced
draft systems.
Table 1.8.15D: Vent Fitting k-Factors
Vertical Draft Hood
Barometric Draft Control
1.50
0.50
Low Resistance Cap
Round Elbow, 90 deg F
Round Elbow, 45 deg F
0.75
0.30
Converging Exit
Cone
(D1/D2)4- 1
(D1 is larger than D2)
Tee or 90 degF Breeching
Y Breeching
1.25
0.75
Tapered Reducer 1 - (D2/D1)4
(D1 is larger than D2)

STEP 5: CORRECT EQUIVALENT INPUT FOR
SYSTEM K-FACTOR
The capacities listed in Table 1.8.15C are based
on a system k-factor equal to 7.5. For any other
k-factor, the vent capacity must be adjusted. This
is accomplished by adjusting the equivalent input
for the system using a k-factor correction factor,
designated F3.
Refer to Table 1.8.15E for the equivalent input
correction factor which applies to the k-factor
calculated in Step 4. This factor is designated as
F3.
Multiply the equivalent input calculated in Step 2
times factor F3from Table 1.8.15E. This step will
yield a new equivalent input, I:
I = MBH x F1x F2x F3eq. 15E
Using this adjusted equivalent input, check the
stack diameter by following Steps 2 thru 3 again.
If the stack diameter remains the same, the sizing
is complete. If not, redo Steps 4 thru 5 etc. until
an acceptable result is achieved.
Table 1.8.15E: K-Factor Equivalent Input Correction Factor F3
K- Factor F3K- Factor F3K- Factor F3K- Factor F3K- Factor F3
1.00 0.37
1.50 0.45
2.00 0.52
2.50 0.58
3.00 0.63
3.50 0.68
4.00 0.73
4.50 0.77
5.00 0.82
5.50 0.86
6.00 0.89
6.50 0.93
7.00 0.97
7.50 1.00
8.00 1.03
8.50 1.06
9.00 1.10
9.50 1.13
10.00 1.15
10.50 1.18
11.00 1.21
11.50 1.24
12.00 1.26
12.50 1.29
13.00 1.32
13.50 1.34
14.00 1.37
14.50 1.39
15.00 1.41
15.50 1.44
16.00 1.46
16.50 1.48
17.0 1.51
17.50 1.53
18.00 1.55
18.50 1.57
19.00 1.59
19.50 1.61
20.00 1.63
20.50 1.65
21.00 1.67
21.50 1.69
22.00 1.71
22.50 1.73
23.00 1.75

Stack
Diam.
(in.)
Table 1.8.15C: Approximate Stack Capacities (MBH)
(Based on Atmospheric Boiler with Draft Hood)
5 7 10 12 15 20 25 30 35 40 45 50 60 70 80 90 100 125 150 200
6 100 120 140 150 170 200 220 250 270 280 300 320 350 380 400 430 450 510 550 640
7 130 160 190 210 240 270 310 340 360 390 410 430 480 510 550 580 620 690 760 870
8 180 210 250 280 310 360 400 440 480 510 540 570 620 670 720 760 810 900 990 1140
9 220 270 320 350 390 450 510 560 600 640 680 720 790 850 910 970 1020 1140 1250 1450
10 280 330 400 430 490 560 630 690 750 800 850 890 980 1060 1130 1200 1260 1410 1550 1790
12 400 480 570 630 700 810 910 1000 1080 1150 1220 1290 1410 1520 1630 1730 1820 2040 2330 2580
14 550 650 780 860 960 1110 1240 1360 1470 1570 1660 1750 1920 2070 2220 2350 2480 2770 3040 3510
16 720 850 1020 1120 1250 1450 1620 1770 1920 2050 2170 2290 2510 2710 2900 3070 3240 3620 3970 4590
18 910 1080 1290 1420 1590 1830 2050 2250 2430 2590 2750 2900 3180 3430 3670 3890 4100 4590 5030 5810
20 1130 1340 1600 1750 1960 2260 2530 2770 3000 3200 3400 3580 3920 4240 4530 4810 5070 5670 6210 7170
22 1370 1620 1940 2120 2370 2740 3060 3360 3630 3880 4110 4340 4750 5130 5480 5820 6130 6860 7510 8680
24 1630 1930 2300 2530 2820 3260 3650 4000 4320 4610 4900 5160 5650 6110 6530 6920 7300 8160 8940 10330
26 1910 2260 2710 2960 3320 3830 4280 4690 5070 5420 5750 6060 6640 7170 7660 8130 8570 9580 10490 12120
28 2220 2630 3140 3440 3850 4440 4970 5440 5880 6280 6660 7030 7700 8310 8890 9430 9940 11110 12170 14060
30 2550 3010 3600 3950 4420 5100 5700 6250 6750 7210 7650 8070 8840 9540 10200 10820 11410 12760 13970 16140
32 2900 3430 4100 4490 5020 5800 6490 7110 7680 8210 8710 9180 10050 10860 11610 12310 12980 14510 15900 18360
34 3270 3870 4630 5070 5670 6550 7320 8020 8670 9270 9830 10360 11350 12260 13110 13900 14650 16390 17950 20730
36 3670 4340 5190 5670 6360 7350 8210 9000 9720 10390 11020 11620 12730 13750 14700 15590 16430 18370 20120 23240
48 6530 7730 9230 10120 11310 13060 14600 16000 17280 18470 19600 20660 22630 24400 26130 27710 29210 32660 35780 41320
54 8260 9780 11690 12810 14320 16530 18480 20250 21870 23380 24800 26140 28640 30930 33070 35080 36970 41340 45290 52290
60 10200 12070 14430 15810 17680 20410 22820 25000 27000 28870 30620 32280 35360 38190 40830 43310 45650 51040 55910 64560
72 14700 17390 20780 22770 25460 29400 32870 36000 38890 41570 44100 46480 50920 55000 58800 62360 65740 73500 80510 92970
NOTE: The above vent input capacities in MBH (thousands of Btu/hr) are sea level ratings for double wall or insulated vents allowing for a system K factor of
7.5. Apply the correction factors for altitude, other k-factors and boiler draft control correction factors.

Table 1.8.15F: CIRCULAR EQUIVALENTS OF RECTANGULAR BREECHINGS & STACKS
WIDTH
(INCHES)
HEIGHT (INCHES)
6 8 10 12 14 16 18 20 22 24 26 28 30 36 42 48 54 60
6 7 8 8 9 10 10 11 11 12 12 13 13 14 15 16 17 17 18
8 8 9 10 11 11 12 13 13 14 15 15 16 16 15 19 20 21 21
10 8 10 11 12 13 14 15 15 16 17 17 18 18 17 21 22 23 24
12 9 11 12 13 14 15 16 17 18 18 19 20 20 20 23 25 26 27
14 10 11 13 14 15 16 17 18 19 20 21 21 22 22 26 27 29 30
16 10 12 14 15 16 17 19 20 20 21 22 23 24 24 28 29 31 32
18 11 13 15 16 17 19 20 21 23 23 24 24 25 26 29 31 33 34
20 11 13 15 17 18 20 21 22 24 24 25 26 27 27 31 33 35 37
22 12 14 16 18 19 20 22 23 25 25 26 27 28 29 33 35 37 39
24 12 15 17 18 20 21 23 24 26 26 27 28 29 31 34 37 39 40
26 13 15 17 19 21 22 24 25 27 27 28 29 31 32 36 38 40 42
28 13 16 18 20 21 23 24 26 28 28 29 31 32 35 37 40 42 44
30 14 16 18 20 22 24 25 27 31 29 31 32 33 36 39 41 44 46
36 15 17 20 22 24 26 27 29 33 32 33 35 36 39 42 45 48 50
42 16 19 21 23 26 28 29 31 35 34 36 37 39 42 46 49 52 55
48 17 20 22 25 27 29 31 33 37 37 38 40 41 45 49 52 56 59
54 17 21 23 26 29 31 33 35 39 39 40 42 44 48 52 56 59 62
60 18 21 24 27 30 32 34 37 39 40 42 44 46 50 55 59 62 66
1.8.16 SPECIAL APPLICATIONS
FLUE GAS ECONOMIZERS
When applying flue gas economizers, care must
be taken to assure that:
1. Proper draft must be maintained. This requires
that the gas side pressure drop be considered
and that the economizer exchanger must be
designed so as to allow cleaning.
2. The vent system materials must be considered,
regarding resistance from corrosion, which might
result from the lower flue gas temperature.
3. In general, it is recommended that the boiler
manufacturer be consulted when a flue gas
economizer is to be added.
HIGH EFFICIENCY APPLIANCES
High efficiency appliances require special
consideration in vent design because of the
reduced stack gas temperatures. Under no
circumstances can a condensing type appliance
be vented into the same vent system with other
appliances. The vent system for such appliances
must be provided by or specified specifically by
the manufacturer of the condensing appliance.
High efficiency non-condensing appliances
should generally be installed only on vent
systems that are resistant to corrosion from flue
gas condensate. This generally requires stainless
steel vent construction.