HORIZONTAL VENTING
NOTE − Common venting is not allowed when horizontally
venting the unit heater.
If the unit heater is to be horizontally vented, a positive
pressure may be created in the vent. The unit heater, when
installed with horizontal venting, will perform as a category
III appliance. See table 4 for horizontal venting requirements
1)
In residential applications which include horizontal
venting, use only special vent materials approved for
use with Category III appliances for the exhaust pipe.
Refer to table 5 for venting components.
In commercial applications, single-wall (26 GSG)
galvanized or equivalent stainless steel vent pipe sealed
per these instructions, OR listed special vent for
Category III appliances may be used for the exhaust
pipe.
Single-wall vent pipe
or U.L.−listed single−wall flex
connector can be used for the combustion air inlet in
both residential and commercial applications.
2)
In residential and commercial applications
, the
exhaust pipe diameter for horizontal installations shall
be 3" (76mm) on FOA
−45 units, 4” (100mm) on −60 &
−75 units, and 5" (127mm) on −100 and −125 units.
In residential and commercial applications,
the
combustion air inlet pipe diameter for horizontal
installations shall be 3" (76mm) on FOA-45 units and
4" (127mm) on
−60, −75, −100 & −125 units.
3)
The minimum horizontal vent length is 5 feet (2m).
4)
Refer to table 2 for maximum horizontal vent lengths.
5)
If possible, do not terminate the horizontal vent through
a wall that is exposed to prevailing wind. Exposure to
excessive winds can affect unit performance. If such a
termination is necessary, use a wind block to protect the
vent termination from direct winds.
6)
Horizontal vent termination must be free from
obstructions and at least 12" (305mm) above grade level
and maximum snow height.
7)
Do not install a horizontal vent termination directly
below roof eaves or above a public walkway, or any
other area where condensate dripping may be
troublesome and may cause some staining. Avoid
windows where steam may cause fogging or ice
buildup.
8)
Minimum clearance for horizontal vent termination
from any door, window, gravity air inlet, gas or electric
meter, regulators, and relief equipment is 4 feet (1m) for
United States installations.
In Canada, horizontal vent termination must have a
minimum 6-foot horizontal clearance from gas and
electric meters and relief devices.
Refer to latest editions of the ANSI Z223.1 or
CSA−B149 for installation compliance codes or check
with local authorities having jurisdiction.
9)
Vent termination must be a minimum of 4 feet (1m)
below, or 4 feet (1m) horizontally, from any soffit or
under-eave vent.
10)
Vent termination must be a minimum of 6 feet (2m)
from an inside corner formed by two exterior walls. If
possible, leave a 10−foot (3m) clearance.
11)
Vent termination must be a minimum of 10 feet (3m)
from any forced air inlet (includes fresh air inlet for
other appliances, such as a dryer).
12)
When termination is routed through combustible wall,
vent termination must be supported using a listed
clearance thimble. Inside edge of vent termination must
be at least 12" (305mm) from outside wall.
13)
All horizontal vents which use special vent pipe for use
with Category III appliances must terminate with an
approved Category III tee. Opening end must face
downward.
14)
In commercial applications, clearance to combustible
material is 6" (152mm) for single-wall vent material
except where a U.L.−listed thimble is used. Follow
manufacturer’s instructions for clearance to combustible
for type B−1 vent or factory-built chimney.
15)
For horizontal venting, the vent pipe shall be supported
with hangers no more than 3 feet (1m) apart to prevent
movement after installation.
16)
Select a wall termination point that will maintain 1/4"
(6mm) rise per foot (305mm) slope of horizontal run
of vent pipe.
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