Carrier 58MXA Nstallation, Start-Up, And Operating Instructions page 23

FURNACE
NOT IN
HORIZONTAL
SECTION
Fig. 32—Combustion-Air and Vent Pipe Diameter
Transition Location and Elbow Configuration
Table 5—Combustion-Air and Vent Pipe Termina-
tion Clearances
LOCATION
Above grade level or above
anticipated snow depth
Dryer/Water heat vent
From plumbing vent stack
From any mechanical fresh air intake
For furnaces with an input capacity of
100,000 Btuh or less—from any non-
mechanical air supply (windows or doors
which can be opened) or combustion-air
opening
For furnaces with an input capacity greater
than 100,000 Btuh or less—from any non-
mechanical air supply (windows or doors
which can be opened) or combustion-air
opening
From service regulator vent, electric and
gas meters and relief equipment
Above grade when adjacent to public
walkway
* Horizontal distance.
† 18 in. above roof surface in Canada.
‡ 36 in. to electric meter in Canada only.
NOTES:
1. If installing 2 adjacent 58MXA furnaces, refer to Multiventing and Vent
Terminations section for proper vent configurations.
2. When locating combustion-air and vent terminations, consideration must be
given to prevailing winds, location, and other conditions which may cause
recirculation of the appliance's own flue products or the flue products of
adjacent vents. Recirculation can cause poor combustion, inlet condensate
problems, and accelerated corrosion of heat exchangers.
3. Vent termination can not terminate less than 2 ft horizontal and 7 ft above
public walkway or where condensate vapor or droplets may be a hazard.
4. Vent termination must be at least 3 feet above any forced draft inlets within
10 feet horizontal. Vent termination must be at least 3 feet horizontal from
other direct vent appliances intake unless otherwise specified by manufac-
turer.
Furnace combustion-air and vent pipe connections must be at-
tached as shown in Fig. 33. Combustion-air intake plug fitting and
inducer housing alternate vent cap may need to be relocated in
some applications.
NOTE: Slope combustion-air and vent pipes a minimum of 1/4
in. per linear ft with no sags between hangers.
PIPE DIAMETER
TRANSITION IN
VERTICAL SECTION
A93034
CLEARANCE (FT)
U.S.A. Canada
1 1†
3 3
3 3
Note 4 6
1 1
1 3
4* 6‡
Note 3 Note 3
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
AIR
FLOW
COMBUSTION- COMBUSTION-
AIR
VENT
UPFLOW
COMBUSTION-
AIR
VENT
AIR
FLOW
HORIZONTAL-LEFT DISCHARGE
Fig. 33—Combustion-Air and Vent Pipe
When combustion-air pipe is installed above a suspended
ceiling, pipe must be insulated with 3/8-in. thick Armaflex-
type insulation. Combustion-air pipe should also be insulated
when it passes through warm, humid space.
→
An abandoned masonry chimney may be used as a raceway for
properly insulated and supported combustion-air and vent pipes.
Each furnace must have its own set of combustion-air and vent
pipes and be terminated individually, as shown in Fig. 42.
→
Other gas appliances with their own venting system may also use
the abandoned chimney as a raceway providing it is permitted by
local code, the current edition of the National Fuel Gas Code and
the vent or liner manufacturer's installation instructions. Care must
be taken to prevent the exhaust gases from one appliance from
contaminating the combustion air of other gas appliances.
When vent pipe is exposed to temperatures below freezing,
such as when it passes through an unheated space or when a
chimney is used as a raceway, pipe must be insulated as
shown in Table 8 with Armaflex-type insulation.
23
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
AIR
VENT
VENT
COMBUSTION- COMBUSTION-
AIR
AIR
FLOW
DOWNFLOW
COMBUSTION-
AIR
VENT
HORIZONTAL-RIGHT DISCHARGE
Connections
VENT
AIR
AIR
FLOW
A96187