Install Instructions
Page 12
LAARS Heating Systems
3.E Locating Vent and Combustion Air
Terminals (continued)
1. Figure 7 shows the requirements for mechanical vent
terminal clearances for the U.S. and Canada.
2. Vent terminals for condensing appliances or
appliances with condensing vents are not permitted
to terminate above a public walkway, or over an area
where condensate or vapor could create a nuisance
or hazard.
3. Locate the vent terminal so that vent gases cannot be
drawn into air conditioning system inlets.
4. Locate the vent terminal so that vent gases cannot
enter the building through doors, windows, gravity
inlets or other openings. Whenever possible, avoid
locations under windows or near doors.
5. Locate the vent terminal so that it cannot be
blocked by snow. The installer may determine
that a vent terminal must be higher than the
minimum shown in codes, depending upon local
conditions.
6. Locate the terminal so the vent exhaust does not
settle on building surfaces or other nearby objects.
Vent products may damage surfaces or objects.
7. If the boiler uses ducted combustion air from an
intake terminal located on the same wall, see Figure
7 through Figure 8 for proper spacing and orientation.
If the vent termination is located in an area exposed to
high winds, an optional PVC tee (the same diameter as the
vent pipe) may be used. The tee’d vent termination oers
greater protection from wind related operating issues.
Side Wall Combustion Air Terminal
The Manufacturer side wall combustion air terminal, or
concentric terminal must be used when the heater takes air
from a side wall. (See Table 6.) Contact Manufacturer for
AL29-4C termination ttings. Consider the following when
installing the terminal. (See Figure 7 through Figure 8.)
1. Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning uid,
chlorine compounds, etc.)
2. Locate the terminal so that it will not be subject to
damage by accident or vandalism. It must be at least
7 feet (2.1m) above a public walkway.
3. Locate the combustion air terminal so that it cannot
be blocked by snow. The National Fuel Gas Code
requires that it be at least 12 inches (30cm) above
grade, but the installer may determine it should be
higher, depending upon local conditions.
4. If the unit is side-wall vented to the same wall, locate
the vent terminal at least 1 foot (0.3m) above the
combustion air terminal.
5. For concentric vent, follow instructions included
with vent kit.
6. Multiple vent kits should be installed such that the
horizontal distance between the outlet group and the
inlet group is 36” (90cm). (See Figure 6.)
7. The vent outlet for models 80-285 must be no lower
than the center of the air inlet, and must be at least
12” (30cm) away from the air inlet. Vent outlets for
models 399-850 must be at least 12” above the
top of the air inlet, and must be at least 36” (90cm)
horizontally from the air inlet. (See Figure 8.)
Vertical Vent Terminal
When the unit is vented through the roof, the vent must
extend at least 3 feet (0.9m) above the point at which it
penetrates the roof. It must extend at least 2 feet (0.6m)
higher than any portion of a building within a horizontal
distance of 10 feet (3.0m), and high enough above the
roof line to prevent blockage from snow. The vent terminal
included with the unit can be used in both vertical and
horizontal applications. When the combustion air is taken
from the roof, the combustion air must terminate at least
12” (30cm) below the vent terminal. (See Figure 4.)
Vertical Combustion Air Terminal
When combustion air is taken from the
roof, a eld-supplied rain cap or an elbow
arrangement must be used to prevent
entry of rain water. (See Figure 4.) The
opening on the end of the terminal must
be at least 12” (30cm) above the point
at which it penetrates the roof, and high
enough above the roof line to prevent
blockage from snow. When the vent
terminates on the roof, the combustion air
must terminate at least 12” (30cm) below
the vent terminal.
Figure 6. - Multiple Side-Wall Terminals, Air and Vent
IMPORTANT: Terminals must be place such that they remain a
minimum of 12” above the expected snow line. Local codes may
have more specific requirements and must be consulted. Refer to the
NFPA 54 National Fuel Gas Code and your local codes for all
required clearances for venting.