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Boiler Assembly
6.9
Venting System
The resulting combustion products must be
transported through a chimney system to the outside.
It is required to use venting systems approved for use
with condensing, gas-fired equipment.
Prior to placing the boiler in operation, it is required
to verify compatibility between boiler and venting
system.
Check the venting system for air tightness!
Install the venting system per manufacturer's
instructions.
SB Boiler Venting Requirements
The SB Boiler is a category II or IV appliance and the
exhaust vent materials must be UL listed for use with a
category IV appliance: operating temperatures of up to
240° F, positive pressure, condensing flue gas service.
Currently, UL Listed vents of AL29-4C or 316L Stainless
steel and/or CPVC must be used with the SB Boiler.
Proper clearances to combustibles must be maintained
per UL and vent manufacturer.
UL, NFPA 211 and NFPA 54 (National Flue Gas Code
ANSI Z223.1) guidelines are often the basis for state
and local codes. Buderus Hydronic Systems
recommendations follow the guidelines of these
recognized agencies unless there are codes applicable
to the installation site that are more stringent. The
venting and combustion air systems must meet all
applicable code requirements.
Code Required Vent Terminations:
Horizontal Terminations:
Vent terminations should be at least 4 feet below, 1
foot above or 4 feet horizontally from any window,
door or gravity air inlet of a building.
The termination shall be at least 3 feet away from any
other building opening, gas utility meter, service
regulator or the like.
The termination shall be at least 6 feet away from the
combustion air intake of any other appliance.
The bottom of the vent terminal should be at least 12
inches above both finished grade and any snow
accumulation point.
Vent should not terminate over public walkways or
over an area where condensate or vapor could
create a nuisance or be detrimental to the operation
of regulators, meters and other equipment.
Discharges should not be in wind-blocked areas,
corners, or directly behind vegetation.
We reserve the right to make any changes due to technical modifications!
Boiler Installation and Maintenance Manual SB735 • Issue 10/2003
Vertical Terminations:
Roof penetrations should follow all applicable codes
and the vent manufacturer's instructions. The vent
should never be installed at less than the required
clearances to combustible materials per UL, NFPA,
and local codes. "Double-wall or thimble" assemblies
are required when penetrating combustible walls and
roofs.
Vertical discharges should extend at least 2 feet
above the roof through properly flashed penetrations
and at least 2 feet above anything within a 10 foot
horizontal diameter. Discharges that extend more
than 2 feet above the roof must be laterally
supported.
If the vent system is to be connected to an existing
stack, the stack must be UL Listed for Category II or
IV appliances (capable of 240°F, positive pressure
and condensing flue gas operation).
Masonry stacks must be lined and the vent
penetration must terminate flush with and be sealed
to this liner. Vents may enter the stack through the
bottom or side.
SB Boilers vent systems must not be interconnected
to any other venting system; The SB Boiler is
designed to maintain its own vent system.
The exhaust vent must be pitched up toward the
termination a minimum of ¼" in. per foot of length.
Condensate must flow back to the SB Boiler freely,
without accumulating in the vent.
Combustion Air from Outside the Building
If outside combustion air is required, the room shall have
two permanent louvered openings to the outdoors. Each
opening must have a minimum free area of 1 square
inch for each 4,000 Btu/hr of total input rating of all fuel
burning equipment in the space.
When the air is supplied to the room via ducts, two ducts
must be used. Vertical ducts and openings must have a
minimum free area of 1 square inch for each 4,000 Btuh
of the total input rating of all fuel burning equipment in
the space. Horizontal ducts and openings must have a
minimum free area of 1 square inch for each 2,000 Btuh
of the total input rating of all fuel burning equipment in
the space.
The free area of the openings must be taken into
account restrictions from the louvers and screens. The
louver manufacturer should be consulted for the
percentage of free area available. When free area is not
known, metal louvers typically have 60 - 70% of free
area, wooden louvers have between 20 - 25% of free
area. Louvers should be in a fixed position or interlocked
with equipment so that they open automatically during
equipment operation.
Buderus Heiztechnik GmbH • http://www.heiztechnik.buderus.de
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