Page 29
EQUIPMENT IN CONFINED SPACE
(Inlet Air from Ventilated Attic and Outlet Air to Outside)
NOTE
-The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
2
per 1.17kW) per
hour of the total input rating of all equipment in the enclosure.
Ventilation Louvers
Inlet Air
(Minimum
12 in.(305mm) Above
attic floor)
Roof Terminated
Exhaust Pipe
Furnace
*Intake Debris
Screen
(Provided)
FIGURE 27
NOTE
-The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
2
per 1.17kW) per
hour of the total input rating of all equipment in the enclosure.
EQUIPMENT IN CONFINED SPACE
(Inlet Air from Ventilated Crawlspace and Outlet Air to Outside)
Roof Terminated
Exhaust Pipe
Furnace
Ventilation
Louvers
(Crawl space)
*Intake Debris Screen Provided)
Inlet Air
(Minimum
12 in.(305mm)
Above crawl
space floor)
Coupling or
3 in. to 2 in.
Transition
(Field Provided)
FIGURE 28
General Guidelines for Vent Terminations
In Non-Direct Vent applications, combustion air is taken
from indoors or ventilated attic or crawlspace and the flue
gases are discharged to the outdoors. The ML196DFE is
then classified as a non-direct vent, Category IV gas fur
-
nace.
In Direct Vent applications, combustion air is taken from
outdoors and the flue gases are discharged to the out
-
doors. The ML196DFE is then classified as a direct vent,
Category IV gas furnace.
In both Non-Direct Vent and Direct Vent applications, the
vent termination is limited by local building codes. In the
absence of local codes, refer to the current National Fuel
Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current
CSA-B149 Natural Gas and Propane Installation Codes in
Canada for details.
Position termination according to location given in FIG
URE 30 or FIGURE 31. In addition, position termination so
it is free from any obstructions and 12” above the average
snow accumulation. At vent termination, care must be tak
-
en to maintain protective coatings over building materials
(prolonged exposure to exhaust condensate can destroy
protective coatings). It is recommended that the exhaust
outlet not be located within 6 feet (1.8m) of an outdoor
AC unit because the condensate can damage the painted
coating.
NOTE -
See TABLE 15 for maximum allowed exhaust pipe
length without insulation in unconditioned space during
winter design temperatures below 32°F (0°C). If required
exhaust pipe should be insulated with 1/2” (13mm) Ar
-
maflex or equivalent. In extreme cold climate areas, 3/4”
(19mm) Armaflex or equivalent may be necessary. Insu
-
lation must be protected from deterioration. Armaflex with
UV protection is permissable. Basements or other en
-
closed areas that are not exposed to the outdoor ambient
temperature and are above 32 degrees F (0°C) are to be
considered conditioned spaces.
IMPORTANT
Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze-ups and
may block the terminations.
IMPORTANT
For Canadian Installations Only:
In accordance to CSA International B149 installation
codes, the minimum allowed distance between the
combustion air intake inlet and the exhaust outlet
of other appliances shall not be less than 12 inches
(305mm)
.
