B Common Venting; Common Venting; Removing A Boiler From An Existing Common Vent System - Bradford White OmniTech BONH1250 Installation And Operation Instructions Manual

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located in the enclosure. This opening must not be less
than the sum of the areas of all vent connectors in the
confined space.
Other methods of introducing combustion and ventilation
air are acceptable, providing they conform to the
requirements in the applicable codes listed above. In
Canada, consult local building and safety codes, or, in
absence of such requirements, follow CSA B149.1.
2.A.4.b Ducted Combustion Air
The combustion air can be taken through the wall, or
through the roof. When taken from the wall, it must be
taken from out-of-doors by means of the Laars horizontal
wall terminal. When taken from the roof, a field-supplied
rain cap or an elbow arrangement must be used to
prevent entry of rain water (see Figure 3).
Use pipe of the appropriate size and material (see
sections 2.A.1 and 2.A.2), for the combustion air intake.
Route the intake to the heater as directly as possible.
Seal all joints with tape. Provide adequate hangers. The
unit must not support the weight of the combustion air
intake pipe. Maximum linear pipe length allowed is 100
feet (30.4m). subtract 5 allowable linear feet (1.5m) for
every additional elbow used.
In addition to air needed for combustion, air shall also
be supplied for ventilation, including all air required for
comfort and proper working conditions for personnel.
The unit loses less than 1 percent of its input rating to the
room, but other heat sources may be present.
Operation of appliances with a blocked common vent
may lead to serious injury or death. Safety devices
must be implemented to prevent blocked common vent
operation. If safe operation of all appliances connected
to a common vent cannot be assured, including
prevention of spillage of flue gasses into living spaces,
common venting should not be applied, and appliances
should each be vented separately.
ADVERTISSEMENT
Le fonctionnement des appareils avec un évent
commun bloqué peut entraîner des blessures graves
ou la mort. Des dispositifs de sécurité doivent être mis
en place pour empêcher le fonctionnement de l'évent
commun bloqué. Si le fonctionnement en toute sécurité
de tous les appareils connectés à un évent commun
ne peut être assuré, y compris la prévention du
déversement de gaz de combustion dans les espaces
de vie, une ventilation commune ne doit pas être
appliquée et les appareils doivent chacun être ventilés
séparément.
WARNING

2.B Common Venting

2.B.1

Common Venting

This unit can be common vented; however, the common
venting must be a professionally designed and approved
system. When common venting a fan-assisted unit
with other appliances through one shared vertical duct
called a "common vent", special care must be taken by
the installer to ensure safe operation. In the event that
the common vent is blocked, it is possible, especially
for fan-assisted devices, to vent backwards through
non-operating appliances sharing the vent, allowing
combustion products to infiltrate occupied spaces. If the
appliances are allowed to operate in this condition,
serious injury or death may occur.
It is for this reason that, in addition to following proper
vent sizing, construction and safety requirements from
the National Fuel Gas Code, ANSI Z223.1 or in Canada,
from CSA B149.1 as well as all applicable local codes, it
is required that installers provide some means to prevent
operation with a blocked common vent. It is suggested
that a blocked vent safety system be employed such that
all appliances attached to the vent be locked out and
prevented from operating under blockage conditions.
As an additional precaution, it is recommended that a
Carbon Monoxide (CO) alarm be installed in all enclosed
spaces containing combustion appliances. If assistance
is required in determining how a blocked vent safety
system should be connected to a LAARS product,
please call Application Engineering at the Rochester
phone number listed on back cover of this manual.
Refer to the installation and operating instructions on
all appliances to be common vented for instructions,
warnings, restrictions and safety requirements. If safe
operations of all appliances connected to a common
vent cannot be assured, including prevention of spillage
of flue gasses into living spaces, common venting should
not be applied, and appliances should each be vented
separately.
2.B.2 Removing a Boiler From an Existing
Common Vent System
NOTE: This section does not describe a method for
common venting this unit. It describes what must
be done when a unit is removed from a common
vent system. Contact the factory or your factory
representative if you have questions about common
venting this unit.
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.