Rinnai RH180 Operation And Installation Manual page 15

Combus on Air Requirements
Using Indoor Air For Combus on
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 Combus on 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 bo om, of the confined space. The openings shall communicate to the outside by
one of two ways:
Directly through horizontal ducts
When communica ng directly with the outdoors
through horizontal ducts, each opening shall have a
minimum free area of 1 in
kW) of total input ra ng of all appliances in the
confined space.
Note: If ducts are used, the cross sec onal area of
the duct must be greater than or equal to the
required free area of the openings to which they are
connected.
When communica ng indirectly with the outdoors
through ver cal ducts, each opening shall have a
minimum free area of 1 in
kW) of total input ra ng of all appliances in the
confined space. Combus on air to the appliance can
be provided from a well ven lated a c or crawl
space.
2
/2000 Btu/hr (1100 mm
2
/4000 Btu/hr (550 mm
Indirectly through ver cal ducts
2
/
2
/
RH180 Manual 15