18
Figure 19a. Vent Termination Clearances for Direct Vent Furnaces
VENT TERMINAL
AIR SUPPLY INLET
AREA WHERE TERMINAL IS NOT PERMITTED
1
In accordance with the current CSA B149.1
Natural Gas and Propane Installation Code
2
In accordance with the current ANSI Z223.1 / NFPA 54
National Fuel Gas Code
† A vent shall not terminate directly above a sidewalk or paved driveway that is located between two single family dwellings and
serves both dwellings.
‡ Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor.
*
For clearances not specified in ANSI Z223.1 / NFPA 54 or CSA B149.1, the following statement shall be included:
“Clearance in accordance with local installation codes, and the requirements of the gas supplier
and the manufacturer’s installation instructions.”
These condensing furnaces are classified as
"Category IV" appliances, which require special
venting materials and installation procedures.
Category IV appliances operate with positive
vent pressure and therefore require vent sys-
tems which are thoroughly sealed. They also
produce combustion condensate, which is
slightly acidic and can cause severe corrosion
of ordinary venting materials. Furnace opera-
tion can be adversely affected by restrictive
vent and combustion air piping. Therefore,
vent
and combustion air piping lengths must conform
completely to the requirements of Table 4.
The furnace must be vented to the outdoors. It
must not be vented in common with any other
Canadian Installations
1
US Installations
2
A =
Clearance above grade, veranda, porch,
deck, or balcony
12 inches (30 cm)
12 inches (30 cm)
B =
Clearance to window or door that may be
opened
6 inches (15 cm) for appliances
≤
10,000
Btuh (3 kW), 12 inches (30 cm) for
appliances > 10,000 Btuh (3 kW) and
≤
100,00 Btuh (30 kW), 36 inches (91 cm) for
appliances >100,00 Btuh (30 kW)
6 inches (15 cm) for appliances
≤
10,000
Btuh (3 kW), 9 inches (23 cm) for
appliances > 10,000 Btuh (3 kW) and
≤
50,000 Btuh (15 kW), 12 inches (30 cm) for
appliances > 50,000 Btuh (15 kW)
C =
Clearance to permanently closed window
*
*
D =
Vertical clearance to ventilated soffit
located above the terminal within a
horizontal distance of 2 feet (61 cm) from
the center line of the terminal
*
*
E =
Clearance to unventilated soffit
*
*
F =
Clearance to outside corner
*
*
G =
Clearance to inside corner
*
*
H =
Clearance to each side of center line
extended above meter/regulator assembly
3 feet (91 cm) within a height 15 feet
above the meter/regulator assembly
*
I =
Clearance to service regulator vent outlet
3 feet (1.83 m)
*
J =
Clearance to nonmechanical air supply inlet
to building or the combustion air inlet to any
other appliance
6 inches (15 cm) for appliances
≤
10,000
Btuh (3 kW), 12 inches (30 cm) for
appliances > 10,000 Btuh (3 kW) and
≤
100,00 Btuh (30 kW), 36 inches (91 cm) for
appliances >100,00 Btuh (30 kW)
6 inches (15 cm) for appliances
≤
10,000
Btuh (3 kW), 9 inches (23 cm) for
appliances > 10,000 Btuh (3 kW) and
≤
50,000 Btuh (15 kW), 12 inches (30 cm) for
appliances > 50,000 Btuh (15 kW)
K =
Clearance to a mechanical air supply inlet
6 feet (1.83 m)
3 feet (91 cm) above if within 10 feet (3 m)
horizontally
L =
Clearance above paved sidewalk or paved
driveway located on public property
7 feet (2.13 m) †
*
M =
Clearance under veranda, porch deck, or
balcony
12 inches (30 cm) ‡
*
Summary of Contents for TC060
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