Intertek MVM97 Series Installation Instructions Manual page 12

(1)*Where directly communicating with the outdoors or where communicating to the outdoors through vertical ducts, each opening shall have a minimum
free area of 1 in. 2 /4000 Btu/hr (550 min
A.9.3.3.1(1)(b).]
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.
(2)*Where communicating with the outdoors through horizontal ducts, each
opening shall have a minimum free area of 1 in.
kW) of total input rating of all appliances in the enclosure. [See Figure
A.9.3.3.1(2).]
9.3.3.2* One Permanent Opening Method. One permanent openings, com-
mencing 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 communicate through a vertical or hori-
zontal 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
located in the enclosure, and
(2) Not less than the sum of the areas of all vent connectors in the space.
12
2 /kW) of total input rating of all appliances in the enclosure. [See Figure A.9.3.3.1(1)(a) and Figure
2
/2000 Btu/hr (1100 min
2
per kW) of the total input rating of all appliances
Figure A.9.3.3.1(1)(b) All Combustion Air
From Outdoors through Ventilated Attic.
2
/
Figure A.9.3.3.1(2) All Combustion Air From Outdoors
through Horizontal Ducts.
Figure A.9.3.3.2 All Combustion Air
From Outdoors through Single Combustion Air Opening.