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VII. Venting (continued)
b. Natural gas and propane installation code specifies
venting systems and air supply for appliances. Air
supply shall be provided when either an appliance
or a combination of appliances has a total input
exceeding 400,000 Btu/h.
c. Air supply is defined as combustion air, excess air,
flue gas dilution air, primary air, secondary air,
and ventilation air. The air supply requirements
below are a summation of Clause 8.4 specific to
this gas appliance.
3. Air Supply Requirements for Appliances having an
input exceeding 400 MBH:
a. Ventilation Air: an opening for ventilation air at
the highest point that opens to the outdoors
shall provide Ventilation of the space. The cross
sectional area of this opening shall be at least
10% of the area required for combustion air, but
in no case shall the cross-sectional area be less
2
than 10 in
(6500 mm
b. Combustion Air: For combustion air where
the air supply is provided by natural airflow
from outdoors, in addition to the opening for
ventilation air, there shall be permanent opening
having a total cross-sectional free area of not less
2
than 1 in
for each 30,000 BTU/hr. (70 mm
each kW) of the total rated input of the boiler(s).
The location of the opening(s) shall not interfere
with the openings for ventilation air. Please
refer to the codes listed above for combustion
air openings when natural draft, fan assisted or
power draft assisted equipment are in the space.
WARNING
WARNING
Asphyxiation Hazard. Common manifold venting
requires special considerations. Follow the instruc-
tions in this manual
Thermal Solutions takes no responsibility for vent
systems that create issues and or affect the per-
formance of the appliance.
Improper Installation of a Category II vent system
resulting in positive pressure in the vent system
can result in flue gas spillage and carbon monoxide
emissions, causing severe personal injury or death.
Sources of combustion air contaminants, including
chlorines, chlorofluorocarbons (CFC's), petroleum
distillates, detergents, volatile vapors or other
chemicals must not be present in the boiler room.
If any of these contaminants are present, severe
corrosion and failure will result.
AMP 400-1000L I&O Manual
2
).
2
for
c. When an air supply duct is used to supply
combustion air, its discharge opening shall be
located where there is no possibility of cold air
affecting steam/water lines or other temperature
sensitive equipment.
4. Combustion Air Supply Dampers, Louvers, and
Grilles
a. The free area of the combustion air supply
opening shall be calculated by subtracting the
blockage area of all fixed louvers, grilles or screens
from the gross area of the opening.
b. Openings in a fixed louver, grille, or screen shall
have no dimension smaller than ¼" (6 mm).
c. No manually operated dampers or manually
operated adjustable louvers are permitted.
d. Motorized dampers or Louvers shall be interlocked
so the burner(s) cannot operate unless the
damper or louver is in the fully open position.
5. Mechanical Combustion Air Supply
a. When combustion air is supplied by mechanical
means, an airflow sensing device shall be installed
and wired into the safety limit circuit of the
primary safety control to shut off the gas in the
event of an air supply failure.
6. Appliance Venting
a. This appliance is listed as Category IV venting and
requires special venting systems as previously
described.
i.
Venting for Category IV appliances shall be as
specified or furnished by the manufacturer of
the listed appliance.
ii. A special venting system shall be installed in
accordance with the terms of its listing and the
vent manufacturers certified installation manual.
iii. A flue gas vent or a vent connector shall not be
installed inside either a duct or a shaft used for
return air, hot air, ventilating air, or combustion
air.
iv. An appliance that operates at a positive vent
pressure shall not be connected to a venting
system serving any other appliance. This
appliance operates at a positive vent pressure.
v. A factory-built chimney used for venting an
appliance shall be certified.
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