LAARS Mascot LX MLXC 175 MBH - Install and Operating Manual - Manual (Page 17)

Mascot LX Boilers and Water Heaters Page 13
Figure 11. Combustion Air and Vent Through Roof.
3.3.2 Side Wall Combustion Air Terminal
The LAARS side wall combustion air terminal, or
concentric terminal ( see Table 5 ), must be used when the
heater takes air from a side wall. Consider the following
when installing the terminal ( see Figure 12 ):
1. Do not locate the air inlet terminal near a source
of corrosive chemical fumes (e.g., cleaning fluid,
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. For concentric vent, follow instructions included
with vent kit.
5. Multiple vent kits should be installed such that the
horizontal distance between outlet group and inlet
group is 36" (90cm) minimum.
6. Vent outlet must be no lower than the center of the
air inlet, and must be at least 12" (30cm) away from
the air inlet (see Figure 10 ).
3.3 Locating Vent & Combustion Air
Terminals
3.3.1 Side Wall Vent Terminal
The appropriate Laars side wall vent terminal must be
used. The terminal must be located in accordance with
ANSI Z223.1/NFPA 54 and applicable local codes. In
Canada, the installation must be in accordance with CSA
B149.1 or .2 and local applicable codes. Consider the
following when installing the terminal:
1.
Figure 12 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 or water heater uses ducted combustion
air from an intake terminal located on the same
wall, see Figure 12 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
offers greater protection from wind related operating
issues.