Laars Mascot II, Installation And Operation Instructions Manual

LAARS Heating Systems

Page 10

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 confined 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 field-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 shall

also be supplied for ventilation, including air required for
comfort and proper working conditions for personnel.

SECTION 3.
Venting and Combustion Air

Laars Mascot II includes a standard
CPVC vent/combustion air adapter. If
field connections require use of PVC/
CPVC vent materials, the installer must
use proper adhesive to join CPVC and/
or PVC pipe and fittings.

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 the

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 Terminal Kits.