INSTALLATION INSTRUCTIONS
Gas Furnace: (F/G)9MAE
440 01 4300 02
9
Specifications subject to change without notice.
Air for Combustion and
Ventilation
Introduction
Direct Vent (2
−
Pipe) Applications
When the furnace is installed as a direct vent (2-pipe) furnace,
no special provisions for air for combustion are required.
However, other gas appliances installed in the space with the
furnace may require outside air for combustion. Follow the
guidelines below to insure that other gas appliances have
sufficient air for combustion.
Ventilated Combustion Air Applications
When the furnace is installed using the ventilated combustion
air option, the attic or crawlspace must freely communicate with
the outdoor to provide sufficient air for combustion. The
combustion air pipe cannot be terminated in attics or
crawlspaces that use ventilation fans designed to operate
during the heating season. If ventilation fans are present in
these areas, the combustion air pipe must terminate outdoors
as a Direct Vent/ 2-Pipe system.
All air for combustion is piped directly to the furnace from a
space that is well ventilated with outdoor air (such as an attic,
crawlspace, or equipment closet) and the space is well isolated
from the living space or garage. In addition, other gas
appliances installed in the space with the furnace may require
outside air for combustion. Follow the guidelines below to
insure that the roof or crawlspace walls have sufficient free
area to provide sufficient air for combustion and ventilation for
the furnaces. The guidelines below can be used to insure that
other gas appliances have sufficient air for combustion.
Provisions for adequate combustion, ventilation, and dilution air
must be provided in accordance with:
U.S. Installations:
Section 9.3 of the NFPA 54/ANSI
Z223.1
−
2012 , Air for Combustion and Ventilation and
applicable provisions of the local building codes.
Canadian Installations:
Part 8 of
CAN/CSA
−
B149.1
−
2010, Venting Systems and Air
Supply for Appliances and all authorities having
jurisdiction.
!
CAUTION
FURNACE CORROSION HAZARD
Failure to follow this caution may result in furnace damage.
Air for combustion must not be contaminated by halogen compounds,
which include fluoride, chloride, bromide, and iodide. These elements
can corrode heat exchangers and shorten furnace life. Air contaminants
are found in aerosol sprays, detergents, bleaches, cleaning solvents,
salts, air fresheners, and other household products.
!
WARNING
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury or death.
The operation of exhaust fans, kitchen ventilation fans, clothes dryers,
attic exhaust fans or fireplaces could create a NEGATIVE PRESSURE
CONDITION at the furnace. Make
−
up air MUST be provided for the
ventilation devices, in addition to that required by the furnace. Refer to
the Carbon Monoxide Poisoning Hazard warning in the venting section
of these instructions to determine if an adequate amount of make
−
up air
is available.
Figure 6
Air for Combustion, Ventilation,
and Dilution for Outdoors
*Minimum dimensions of 3‐in. (76mm)
NOTE
: Use any of the following combinations of openings:
A & B, C & D, D & E, F & G
L12F012
Outdoor Combustion Air Method
1. Provide the space with sufficient air for proper
combustion, ventilation, and dilution of flue gases using
permanent horizontal or vertical duct(s) or opening(s)
directly communicating with the outdoors or spaces that
freely communicate with the outdoors.
2.
Figure 6
illustrates how to provide TWO OUTDOOR
OPENINGS, one inlet and one outlet combustion and
ventilation air openings to the outdoors.
a. One opening
MUST
commence within 12-in.
(300 mm) of the ceiling and the second opening
MUST commence within 12-in. (300 mm) of the floor.
b. Size openings and ducts per
Figure 6
and
Table 3
.
c. TWO HORIZONTAL DUCTS require 1 square inch
(25.4 square mm) of free area per 2,000 Btuh (1,100
mm
2
/kW) of combined input for all gas appliances in
the space per
Figure 6
and
Table 3
.
d. TWO OPENINGS OR VERTICAL DUCTS require 1
square inch (25.4 square mm)of free area per 4,000
Btuh (550 mm
2
/kW) for combined input of all gas
appliances in the space per
Figure 6
and
Table 3
.
3. ONE OUTDOOR OPENING requires:
a. 1 sq. in. (25.4 square mm)of free area per 3,000 Btuh
(734 mm
2
/kW) for combined input of all gas
appliances in the space per
Table 3
and
b. Not less than the sum of the areas of all vent
connectors in the space.
The opening shall commence within 12-in. (300 mm) of the
ceiling. Appliances in the space shall have clearances of at
least 1-in. (25 mm) from the sides and back and 6-in. (150 mm)
from the front. The opening shall directly communicate with the
outdoors or shall communicate through a vertical or horizontal
duct to the outdoors or spaces (crawl or attic) that freely
communicate with the outdoors.
