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• Provide two permanent openings to allow
circulation of combustion air.
• A minimum free area of each openings
• 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.
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.
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)
