Intertek ACVC96 Service Instructions Manual page 19

INSTALLATION CONSIDERATIONS
(1)*Where directly communicating with the outdoors or where commu-
nicating to the outdoors through vertical ducts, each opening shall
have a minimum free area of 1 in.
total input rating of all appliances in the enclosure. [See Figure
A.9.3.3.1(1)(a) and Figure A.9.3.3.1(1)(b).]
Chimney or Gas Vent
Water
Heater
Furnace
Alternate
air inlet
Ventilation louvers for
unheated crawl space
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.
Chimney or Gas Vent
Ventilation louvers
(each end of attic)
Water
Heater
Furnace
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 enclo-
sure. [See Figure A.9.3.3.1(2).]
2
/4000 Btu/hr (550 min
Ventilation louvers
(each end of attic)
NOTE: The inlet and outlet air
openings must each have a free
area of not less than one square
inch per 4000 BTU of the
total input rating of all equipment
in the enclosure.
Outlet Air
Inlet Air
NOTE: The inlet and outlet air
openings must each have a free
area of not less than one square
inch per 4000 BTU of the
total input rating of all equipment
in the enclosure.
Outlet Air
Inlet air duct
[ends 1 ft (300 mm)
above floor]
2
/2000 Btu/hr
Chimney or Gas Vent
2
/kW) of
Furnace
Figure A.9.3.3.1(2) All Combustion Air From Outdoors
9.3.3.2* One Permanent Opening Method. One permanent open-
ings, 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 communicate 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.
NOTE: The single opening must have
a free area of not less than one
square inch per 3000 BTU of
the total input rating of all equip-
ment in the enclosure, but not less than
the sum of the areas of all vent
connectors in the confined space.
Figure A.9.3.3.2 All Combustion Air
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 accor-
dance 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
calculated 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.
NOTE: The air duct openings
must have a free area of not
less than one square inch per
2000 BTU of the total input
rating of all equipment in the
enclosure*.
Outlet air duct
Water
Heater
Inlet air duct
through Horizontal Ducts.
2
per kW) of the total input rating of all
Chimney or Gas Vent
Water
Heater
Furnace
Opening
Alternate
Opening
Location
19