Rinnai REU-VA1320WF-US Operation And Installation Manual page 15

Combustion Air Requirements
Using Indoor Air For Combustion
When using air from other room(s) in the building, the total volume of the room(s) must be of adequate volume
(Greater than 50 cubic feet per 1000 Btu/hr). Each Combustion air opening must have at least one square inch
of free area for each 1000 Btuh, but not less than 100 square inches each.
through two permanent openings, one commencing within 12 in. (300mm) of the top and one commencing
within 12" (300mm) of the bottom, of the confined space. The openings shall communicate to the outside by
one of two ways:
Directly through horizontal ducts
When communicating directly 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
confined space.
Note: If ducts are used, the cross sectional area of
the duct must be greater than or equal to the
required free area of the openings to which they are
connected.
When communicating indirectly with the outdoors
through vertical ducts, each opening shall have a
minimum free area of 1 in
kW) of total input rating of all appliances in the
confined space. Combustion air to the appliance can
be provided from a well ventilated attic or crawl
space.
2
/2000 Btu/hr (1100 mm
2
/4000 Btu/hr (550 mm
RH180 Manual
Indirectly through vertical ducts
2
/
2
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