LAARS Heating Systems
Page 12
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” (300 mm) 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.
3.B Combustion Air
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.
This 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.C 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. (See the
following descriptions.) 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” (300 mm) of the top and
one commencing within 12” (300 mm) of the bottom,
of the enclosure shall be provided. The openings
Table 6. Ducted Air Accessories
(Place in section 3.1)
Model 1600 Model 2000 Model 2500 Model 3000 Model 3500 Model 4000
Screen for horizontal galvanized air pipe
D2012104
D2012101
D2012101
D2012102
D2012103
D2012103
Screen for horizontal PVC air pipe
CA012004
CA012001
CA012001
CA012002
CA012003
CA012003
Screen for horizontal polypropylene air pipe
CA012204
CA012201
CA012201
CA012202
CA012203
CA012203
Screen for vertical galvanized air pipe
D2012204
D2012201
D2012201
D2012202
D2012203
D2012203
Screen for vertical PVC air pipe
CA012404
CA012401
CA012401
CA012402
CA012403
CA012403
Screen for vertical polypropylene air pipe
CA012604
CA012601
CA012601
CA012602
CA012603
CA012603
Table 3a - Ducted Air Accessories
(Place in section 3.2)
Model 1600 Model 2000 Model 2500 Model 3000 Model 3500 Model 4000
Horizontal vent terminal for stainless steel
D2012004
D2012001
D2012001
D2012002
D2012003
D2012003
Screen for horizontal CPVC vent
CA012104
CA012101
CA012101
CA012102
CA012103
CA012103
Screen for vertical stainless steel vent
D2012304
D2012301
D2012301
D2012302
D2012303
D2012303
Screen for vertical CPVC vent
CA012504
CA012501
CA012501
CA012502
CA012503
CA012503
Table 3* - Vent Accessories
(Place in section 3.5)
Model 1600 Model 2000 Model 2500 Model 3000 Model 3500 Model 4000
Air intake screen for unit placed outdoors
CA0011904
CA011901
CA011901
CA011902 CA0011903 CA0011903
Vent terminal for unit placed outdoors
CA011803
CA011801
CA011801
CA011802
CA011803
CA011803
Table 3** - Air & Vent Accessories for Units Placed Outdoors
Table 7. Required Combustion Air Pipe Material
Material
United States
Canada
ABS
ANSI/ASTM D1527
The air pipe material must be chosen based upon
the intended application of the boiler or water
heater, and must be installed according to the vent
manufacturer’s installation instructions.
PVC, sch. 40
ANSI/ASTM D1785 or D2665
CPVC, sch. 40
ANSI/ASTM F441
Single wall galv. steel
26 gauge
Polypropylene
ULC S636 Class 2C