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2
Non-Direct Vent
Combustion Air
WARNING
This water heater requires adequate combustion air for ventilation and dilution of flue gases. Failure to provide
adequate combustion air can result in unit failure, fire, explosion, serious bodily injury or death. Use the following
methods to ensure adequate combustion air is available for correct and safe operation of this water heater.
Important: Combustion air must be free of corrosive chemicals. Do not provide combustion air from corrosive
environments. Appliance failure due to corrosive air is not covered by warranty.
For applications containing corrosive indoor air, this appliance must be installed as direct vent. DO NOT use room air in
applications where combustion air contains acid forming chemicals such as sulfur, fluorine and chlorine. These
chemicals have been found to cause rapid damage and decay and can become toxic when used as combustion air in
gas appliances. Such chemicals can be found in, but not limited to bleach, ammonia, cat litter, aerosol sprays, cleaning
solvents, varnish, paint and air fresheners. Do not store these products or similar products in the vicinity of this water
heater.
Unconfined Space
An unconfined space is defined in National Fuel Gas Code, ANSI Z223.1/NFPA 54 as "a space whose volume is not less
than 50 cubic feet per 1000 Btu/hr (4.8 m3 per kW per hour) of the aggregate input rating of all appliances installed in
that space. Rooms communicating directly with the space in which the appliances are installed, through openings not
furnished with doors, are considered a part of the unconfined space." If the "unconfined space" containing the
appliance(s) is in a building with tight construction, additional outside air may be required for proper operation.
Outside air openings should be sized the same as for a confined space.
Confined Space
A confined space is defined in the National Fuel Gas Code, ANSI Z223.1/NFPA 54 as "a space whose volume is less than
50 cubic feet per 1000 Btu/hr (4.8 m3 per kW per hour) of the aggregate input rating of all appliances installed in that
space." Examples include a small room, closet, alcove, utility room, etc. A confined space must have two combustion
air openings. Size the combustion air openings based on the BTU input for all gas utilization equipment in the space
and the method by which combustion air is supplied.
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). Combustion air openings between joining
rooms must have at least 1 square inch of free area for each 1000 Btu/hr, but not less than 100 square inches each.
Using Outdoor Air For Combustion
Outdoor air can be provided to a confined space through two permanent openings, one commencing within 12 in.
(0.30 m) of the top and one commencing within 12 in. (0.30 m) of the bottom, of the confined space. The openings
shall communicate to the outside by one of two ways.
When communicating directly with the outdoors through horizontal ducts, each opening shall have a minimum free
2
area of 1 in
/2000 Btu/hr (1100 mm
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.
26
(Room Air)
2
/kW) of total input rating of all appliances in the confined space.
Rinnai Commercial Hybrid System Installation and Operation Manual
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