Goodman *MVM96 Installation Instructions Manual page 12

Figure A.9.3.3.1(1)(a) All Combustion Air From Outdoors -
Inlet Air from Ventilated Crawl Space and Outlet Air
to Ventilated Attic.
Figure A.9.3.3.1(1)(b) All Combustion Air
From Outdoors through Ventilated Attic.
(2)*Where communicating with the outdoors through horizontal ducts,
each opening shall have a minimum free area of 1 in.
2
(1100 min /kW) of total input rating of all appliances in the enclosure.
[See Figure A.9.3.3.1(2).]
Figure A.9.3.3.1(2) All Combustion Air From Outdoors
9.3.3.2* One Permanent Opening Method. One permanent openings,
commencing within 12 in. (300 mm) of the top of the enclosure, shall be
provided. The appliance shall have clearances of at least 1 in. (25 mm)
from the sides and back and 6 in. (150 mm) from the front of the appliance.
The opening shall directly communicate with the outdoors or shall com-
municate through a vertical or horizontal duct to the outdoors or spaces
that freely communicate with the outdoors (see Figure A.9.3.3.2) and shall
have a minimum free area of the following:
2
(1) 1 in. /3000 Btu/hr (700 mm
appliances located in the enclosure, and
(2) Not less than the sum of the areas of all vent connectors in the space.
2
/2000 Btu/hr
From Outdoors through Single Combustion Air Opening.
9.3.4 Combination Indoor and Outdoor Combustion Air. The use of a
combination of indoor and outdoor combustion air shall be in accordance
with (1) through (3) (see example calculation in Annex J]:
(1) Indoor Openings: Where used, openings connecting the interior spaces
shall comply with 9.3.2.3.
(2) Outdoor Opening(s) Location. Outdoor opening(s) shall be located in
accordance with 9.3.3.
(3) Outdoor Opening(s) Size. The outdoor opening(s) size shall be calcu-
lated in accordance with the following:
(a) The ratio of the interior spaces shall be the available volume of
all communicating spaces divided by the required volume.
(b) The outdoor size reduction factor shall be 1 minus the ratio of
interior spaces.
12
through Horizontal Ducts.
2
per kW) of the total input rating of all
Figure A.9.3.3.2 All Combustion Air