Carrier 912SD Installation, Start-Up, Operating And Service And Maintenance Instructions page 35

912SD: Installation, Start-up, Operating and Service and Maintenance Instructions
12" (256mm) minimum
60"(1524 mm) or
1 additional elbow maximum
CASING SIDE OR TOP ATTACHMENT
COMBUSTION AIR PIPE
(NON-DIRECT VENT FOR ALL MODELS EXCEPT MODULATING UNLESS
INSTALLED IN ATTIC OR CRAWL SPACE)
Fig. 44 – Combustion Air Pipe Attachment
Fig. 45 – Pipe Vent and Combustion
Ventilated Combustion Air
The vent pipe for a Ventilated Combustion Air System must terminate
outdoors. See Fig. 48 for references to vent clearances required by
National code authorities. Allowable vent terminations are shown in
Fig. 41. The combustion air pipe terminates in a well-ventilated attic or
crawl space. Follow the clearances as shown in
The combustion air pipe cannot terminate in attics or crawl spaces that
use ventilation fans designed to operate in the heating season. If
ventilation fans are present in these areas, the combustion air pipe must
terminate outdoors as a Direct Vent System.
Non-Direct Vent / 1-Pipe System
The vent pipe for a Non Direct Vent (1-pipe) system must terminate
outdoors. See Fig. 48 for references to vent clearances required by
National Code authorities. Allowable vent terminations are shown in
Fig. 41.
A combustion air inlet pipe to the outdoors is not required for a
Non-Direct (single-pipe) Vent System. A 12-in. long section of pipe with
a tight radius 2-in. (51 mm) 90 degree elbow is required to be attached to
the furnace. See Fig. 49. This short inlet air pipe helps to ensure stable
combustion, as well as allow for sound attenuation. To aid sound
attenuation, point the inlet air pipe away from occupants. An extra elbow
and/or five feet of pipe may be used to accomplish the sound attenuation
function.
Termination Requirements
Saskatchewan
The Provinces of Alberta and Saskatchewan require a minimum
unobstructed distance of 4 ft. (1.2 M) from the foundation to the property
line of the adjacent lot for vent termination of any appliance with an
input over 35,000 BTUh. If there is less than 4 ft. (1.2 M) of
unobstructed distance to the property line of the adjacent lot, no type of
vent termination is permitted for appliances with inputs greater than
35,000 BTUh.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
to
A
Fig. 46.
for the Provinces of Alberta and
There are no additional restrictions on unobstructed distances greater
than 8 ft. (2.4 M). All single, two-pipe and concentric vents may be used,
providing all other Code and manufacturer's requirements in these
instructions are adhered to. Refer to the appropriate Vent Termination
section above for locating the vent termination
If the unobstructed distance from the foundation to the property line of
the adjacent lot is no less than 4 ft. (1.2 M) and no greater than 8 ft. (2.4
M), it will be necessary to re-direct the flue gas plume. In this situation, a
concentric vent kit cannot be used. A 2-pipe termination (or single pipe
termination when permitted) that re-directs the flue gas away by use of
an elbow or tee, certified to ULC S636 from the adjacent property line
must be used. See Fig.
The concentric vent kit currently cannot be modified to attach an elbow
to the vent portion of the rain cap. A tee attached to the rain cap could
potentially direct the flue gas plume toward the intake air stream and
contaminate the incoming combustion air for the furnace.
Refer to Fig. 49 for terminations approved for use in Alberta and
A13406
Saskatchewan.
Size the Vent and Combustion Air Pipes
General
Furnace combustion air and vent pipe connections are sized for 2-in. (50
mm ND) PVC/ABS DWV pipe. The combustion air and vent pipe
connections also accommodate 60 mm polypropylene venting systems
with outside diameters of approximately 60 mm (2-3/8 inches). Any pipe
diameter change should be made outside furnace casing in vertical pipe.
Any change in diameter to the pipe must be made as close to the furnace
as reasonably possible. See
The Maximum Vent Length for the vent and combustion air pipe (when
used) is determined from the Maximum Equivalent Vent Length in
A96128
Table 13 minus the number of fittings multiplied by the deduction for
each type of fitting used from
Pipe hangar
Ventilated Combustion Air
intake termination in crawl
space
Fig. 46 – Vent Terminations for Ventilated Combustion Air
35
49.
Fig. 50.
Table 14.
Ventilated Combustion
Air intake pipe
3" (76 mm)
12" (305 mm)
CRAWL SPACE
ATTIC
highest level of insulation
A10497