Install and Operating Manual User guide
LAARS Heating Systems
Page 8
the enclosure shall be provided. The openings shall
communicate directly, or by ducts, with the outdoors
or spaces that freely communicate with the outdoors.
When directly communicating with the outdoors, or
when communicating to the outdoors through vertical
ducts, each opening shall have a minimum free area
of 1 square inch per 4000 Btu/hr (550 square mm/kW)
of total input rating of all equipment in the enclosure.
When communicating to the outdoors through horizontal
ducts, each opening shall have a minimum free area of
not less than 1 square inch per 2000 Btu/hr (1100 square
mm/kW) of total input rating of all equipment in the
enclosure.
Method 2: One permanent opening, commencing
within 12" (300mm) of the top of the enclosure, shall
be permitted. The opening shall directly communicate
with the outdoors or shall communicate through a
vertical or horizontal duct to the outdoors or spaces
that directly communicate with the outdoors and shall
have a minimum free area of 1 square inch per 3000
Btu/hr (734 square mm/kW) of the total input rating of
all equipment located in the enclosure. This opening
must not be less than the sum of the areas of all vent
connectors in the conned space.
Other methods of introducing combustion and
ventilation air are acceptable, providing they conform to
the requirements in the applicable codes listed above.
In Canada, consult local building and safety codes
or, in absence of such requirements, follow CAN/CGA
B149.
3.1.2 Ducted Combustion Air
The combustion air can be taken through the wall,
or through the roof. When taken from the wall, it must
be taken from out-of-doors by means of the LAARS
horizontal wall terminal, shown in Table 3. See Table 2
to select the appropriate diameter air pipe. When taken
from the roof, a eld-supplied rain cap or an elbow
arrangement must be used to prevent entry of rain water
(see Figure 7).
Use ABS, PVC, CPVC or galvanized pipe for the
combustion air intake (see Table 4), sized per Table 2.
Route the intake to the boiler as directly as possible.
Seal all joints. Provide adequate hangers. The unit must
not support the weight of the combustion air intake pipe.
Maximum linear pipe length allowed is shown in Table
2. Subtract 5 allowable linear ft. (1.5m) for every elbow
used.
The connection for the intake air pipe is at the top
of the unit (see Figure 2).
In addition to air needed for combustion, air
SECTION 3.
Venting and Combustion Air
Laars Mascot II includes a standard
CPVC vent/combustion air adapter. If
eld connections require use of PVC/
CPVC vent materials, the installer must
use proper adhesive to join CPVC and/
or PVC pipe and ttings.
3.1 Combustion Air
Mascot II boilers and water heaters must have
provisions for combustion and ventilation air in
accordance with the applicable requirements for
Combustion Air Supply and Ventilation in the National
Fuel Gas Code, ANSI Z223 1; or in Canada, the Natural
Gas and Propane Installation Code, CSA B149.1. All
applicable provisions of local building codes must also
be adhered to.
A Mascot II unit can take combustion air from
the space in which it is installed, or the combustion
air can be ducted directly to the unit. Ventilation air
must be provided in either case.
3.1.1 Combustion Air from Room
In the United States, the most common
requirements specify that the space shall communicate
with the outdoors in accordance with method 1 or 2,
which follow. Where ducts are used, they shall be of
the same cross-sectional area as the free area of the
openings to which they connect.
Method 1: Two permanent openings, one
commencing within 12" (300mm) of the top and one
commencing within 12" (300mm) of the bottom, of
INSTALLATION STANDARDS
MATERIAL UNITED STATES CANADA
ABS ANSI/ASTM D1527
PVC, sch 40 ANSI/ASTM D1785 or D2665 Air pipe material must be chosen
CPVC, sch 40 ANSI/ASTM F441 based upon the intended application of the boiler.
Single wall galv. steel 26 gauge
Table 4. Required Combustion Air Pipe Material.
CONCENTRIC WALL ROOF
SIZE ADAPTER TERMINAL TERMINAL
125 3CGV-VC 3CGV-AD-LAARS 3CVG-HZC
Table 3b. Approved Stainless Steel
Terminations and Adapters.
HORIZONTAL INTAKE AND EXHAUST PVC VENT TERMINAL
KITS
2" PVC 3" PVC
SIZE Standard Concentric n/a
CA006000
125 included optional contact Laars
Concentric vent terminal = 10 ft. pipe length.
Table 3a. PVC Vent Te
rminal Kits.