Rinnai E75CN Installation & Servicing Instructions Manual page 45

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.
Using Outdoor Air For Combustion
Outdoor air can be provided to a confi ned space through two permanent openings,
one commencing within 12 in. (300mm) of the top and one commencing within 12"
(300mm) of the bottom, of the confi ned space. The openings shall communicate to
the outside by one of two ways:
directly through horizontal ducts
indirectly through vertical 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 confi ned 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 confi ned space. Combustion
air to the appliance can be provided from a well ventilated attic or crawl
space.
Gas Vent / Boiler Exhaust
OUTLET AIR DUCT
INLET AIR DUCT
Gas Vent / Boiler Exhaust
BOILER
INLET AIR DUCT
[Ends 1Ft (300mm)
above floor]
Louvers and grills
BOILER
OUTLET
AIR
2
/2000 Btu/hr (1100 mm
2 /4000 Btu/hr (550 mm
Gas Vent / Boiler Exhaust
OUTLET
AIR
BOILER
INLET
AIR
Ventilation Louvers for
unheated crawl space
2
/
2 /
figure 21
45