22
• Provide two permanent openings to allow circulation
of combustion air.
• A minimum free area of each openings
Indoor make up
air is provided
Outdoor make up air is provided
Direct or
Vertical ducts
Horizontal ducts
200 in
2
20" (W) x 10" (H)
50 in
2
10" (W) x 5" (H)
100 in
2
20" (W) x 5" (H)
Supply combustion air to the units as per the National Fuel Gas Code, ANSI Z223.1-
latest edition and in Canada, in accordance with the Natural Gas and Propane Installa-
tion Code CSA B149.1-latest edition.
Combustion Air
Openings supplying indoor air
H
H
W
W
Provide adequate combustion air so as to not create negative pressure within the building.
• If the unit is installed in a mechanical closet, a
minimum of permanent clearance of 4" or more in
front of the unit is required. A 24" or more clearance
is recommended in order to facilitate maintenance
and repair.
• If combustion air will be provided through a duct, size
the duct to provide 70 cubic feet of fresh air per minute.
• If the unit is installed in a mobile home, outdoor air
must be supplied. The usage of the "-SV" conversion
kit is prohibited.
