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PROVIDING FOR PROPER VENTING THROUGH THE
ROOF
• Vent boiler making Ref. to NFGC section 2 & 10 and
using these instructions and requirements of local
utilities and other local code authorities.
• You must connect boiler to vent or factory-built
chimney. Vent or factory-built chimney must meet
recognized standard.
• Chimney lining method and material must comply with
local code requirements.
• Use corrosion-resistant material meeting nationally
recognized standards for vent construction.
!
Inadequate vent or chimney could allow
combustion products to collect in structure,
resulting in injury or death.
Vent this boiler separately from any appliance
designed to burn solid fuel, particularly wood
!
burning or coal burning appliances. Improper
venting could allow combustion products to
collect in the structure, resulting in injury or
death.
A. VENTING CATEGORY
• Boilers covered by this manual are design-certified
as CATEGORY I for venting. CATEGORY I Appliances
have non-positive vent static pressure and rely on
heat content of combustion products to vent. You may
common vent CATEGORY I boilers.
• Boilers covered by this manual are also design
certified as CATEGORY III for venting, only when they
installed with manufacturer specified vent system
components and installed practices. Ref. pages 12-21
for category 3 venting instructions
B. DESIGN CONSIDERATIONS
• Avoid oversizing boiler for your application. Select a
boiler model with a rated heating output close to the
calculated heating load. This extends the firing period,
decreasing the potential for condensate formation in
the vent.
• Too small a vent cannot carry all combustion products
outdoors. Too large a vent will not vent combustion
products rapidly enough to avoid potential for
condensation. Refer to pages 24 thru 27 for correct
vent size.
VERTICAL VENT PIPE INSTALLATION INSTRUCTIONS
WARNING
WARNING
.
• Vent height must be a minimum of six feet. Minimize
vent connector horizontal runs to the extent possible
for best performance.
• The designer must consider the building's orientation,
answering these questions. (Ref. pages 24-27).
A. Will the vent terminate outside the building where
its operation could be adversely affected by winds?
B. Could any adjacent buildings adversely affect vent
operation?
C. Allowing for these factors can reduce the
possibility of downdraft conditions.
• If your local experience indicates possible condensation
problems, provide for draining and disposal of venting
system condensate.
C. VENT SIZING
• Sometimes horizontal distance from boiler to vent or
chimney is already given; this is known as horizontal
vent connector run. Vent or chimney height is also
usually given as Btuh input of gas appliances served by
vent.
• Check these parameters to be sure venting system will
work. Use approved engineering practices and part 7 &
10 of the latest revision of the (NFGC) National Fuel
Gas Code, ANSI Z233.1/NFPA54.
• Use this venting addendum for single appliance venting
and multiple appliance (common) venting. For multi
story installations, refer to latest revision of National
Fuel Gas Code ANSI Z223.1/NFPA 54.
D. VENT CONNECTOR
• Vent connectors must be made of noncombustible,
corrosion resistant material capable of withstanding
vent gas temperatures. They must be thick enough
to withstand physical damage and be accessible for
inspection, cleaning and replacement.
• Use Type B 1 vent connector in or through attics, crawl
spaces, or other cold areas. Install thimbles that meet
local codes when vent connectors pass through walls or
partitions of combustible material.
• Keep vent connectors as short as possible by locating
boiler as close as practical to vent or chimney. Avoid
unnecessary turns or bends which create resistance to
flow of vent gases. Adding an elbow adds resistance.
For example, adding a 6" 90-degree elbow would
be the equivalent of adding 20 feet of horizontal 6"
pipe. (45-degree elbows have lower resistance than
90-degree elbows, and can work for most vent runs).
• If you join two or more vent connectors before they
enter vertical vent or chimney, see figure 17, on page
24. Also refer to NFGC book, ANSI standards and NFPA
book.
23
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