15
Air Directly Through An Exterior Wall
(See Figure 11)
If combustion air is provided directly through an
exterior wall, the two openings must each have
free area of at least one square inch per 4000
Btuh of total appliance input.
Outdoor Air Using a Crawl Space and Ventilated
Attic (See Figure 12)
When directly communicating with the out-
doors, each opening shall have a minimum free
area of 1 square inch per 4,000 Btuh of total
appliance input. The openings shall communi-
cate directly, or by ducts, with the outdoor
spaces (crawl or attic) that freely communicate
with the outdoors.
Outdoor Air Using Horizontal Ducts
(See Figure 13)
If combustion air is taken from outdoors through
horizontal ducts, the openings and ducts must
have a minimum free area of one square inch
per 2,000 Btuh of total appliance input.
If the unit is installed in an area with an exhaust
fan, provide sufficient ventilation to prevent
negative pressures from occurring in the room.
The combustion air openings must not be re-
stricted in any manner.
VENTING REQUIREMENTS
General
This furnace must be vented in compliance
with, the current revision of the National Fuel
Gas Code (ANSI-Z223.1/NFPA54), with the
instructions provided below.
Figure 12. Equipment in a Confined
Space with All Combustion Air Drawn
from a Crawl Space and Ventilated Attic
Outlet Air Duct
mu
s
t be at lea
s
t
1
s
q. in. per 4000
Btuh of total input
ratin
g
. Mu
s
t extend
above attic in
s
ulation.
Ventilation Louver
s
at
each end of attic
Attic In
s
ulation
Ventilation Louver
s
for
unheated crawl
s
pace
Crawl
S
pace
Inlet Air Duct mu
s
t
be at lea
s
t 1
s
q. in.
per 4,000 Btuh of
total input ratin
g
.
Furnace
Water Heater
Vent or
Chimney
In Canada, venting shall conform to the require-
ments of the current (CAN/CGA B149.1 or .2)
installation codes.
Consult local codes for
special requirements.
For Category I furnace installations, the fur-
nace shall be connected to a factory built
chimney or vent complying with a recognized
standard, or a masonry or concrete chimney
lined with a lining material acceptance to the
authority having jurisdiction.
Venting into an
unlined masonry chimney or concrete chim-
ney is prohibited.
This furnace must never be vented to a chim-
ney flue servicing a fireplace or other appliance
designed to burn solid fuel. If the furnace vent
is to be connected to a chimney serving a
fireplace, the fireplace must be sealed off from
the chimney. Single wall metal vents shall not be
used for Category I venting, Category I fur-
naces must be vented vertically or near verti-
cally.
The furnace vent, if metal, may be insulated if
local codes allow. Any part of the vent system,
metal vent only, not exposed to weather, but
which are exposed to ambient temperatures
below 35° F must be insulated to prevent con-
densation. All vent insulation shall be foil backed
fiberglass of one inch minimum thickness.
Figure 13. Equipment in a Confined Space
with all Combustion Air Drawn from the
Outside through Horizontal Ducts
Each openin
g
to out
s
ide
mu
s
t be at lea
s
t
1
s
q. in. per 2000
Btuh of total input
ratin
g
.
12" Max
12" Max
Total Input
Ratin
g
(Btu/hr)
40,000
60,000
8
0,000
100,000
120,000
140,000
160,000
Minimum
Free Area
(Each Openin
g
)
20
s
q. in.
3
0
s
q. in.
40
s
q. in.
50
s
q. in.
60
s
q. in.
70
s
q. in.
8
0
s
q. in.
Round Duct
Diameter
5"
6"
7"
8
"
9"
10"
10"
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Furnace
Air Duct
Air Duct
Water Heater
Vent or
Chimney
- - -
- - -
- - -
- - -
- - -
- - -
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Содержание TA-060C-08A
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