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Room Air:Combustion Air <br /> A WARNING This water heater requires adequate combustion air for ventilation and dilu- <br /> tion of flue gases. Failure to provide adequate combustion air can result in <br /> unit failure, fire, explosion, serious bodily injury or death. Use the following methods to ensure adequate <br /> combustion air is available for correct and safe operation of this water heater. <br /> IMPORTANT <br /> [Combustion air must be free of corrosive chemicals. Do not provide combustion air from <br /> sive environment.Appliance failure due to corrosive air is not covered by warranty. <br /> For applications containing corrosive indoor air, this appliance must be installed as direct vent. DO NOT <br /> use room air in applications where combustion air contains acid forming chemicals such as sulfur, fluorine <br /> and chlorine. These chemicals have been found to cause rapid damage and decay and can become <br /> toxic when used as combustion air in gas appliances. Such chemicals can be found in, but not limited to <br /> bleach, ammonia, cat litter, aerosol sprays, cleaning solvents, varnish, paint and air fresheners. Do not <br /> store these products or similar products in the vicinity of this water heater. <br /> Unconfined Space <br /> An unconfined space is defined in National Fuel Gas Code,ANSI Z223.1/NFPA 54 as "a space whose <br /> volume is not less than 50 cubic feet per 1000 Btu/hr(4.8 m3 per kW per hour)of the aggregate input <br /> rating of all appliances installed in that space. Rooms communicating directly with the space in which <br /> the appliances are installed, through openings not furnished with doors, are considered a part of the <br /> unconfined space." If the "unconfined space" containing the appliance(s) is in a building with tight <br /> construction, additional outside air may be required for proper operation. Outside air openings should be <br /> sized the same as for a confined space. <br /> Confined Space <br /> A confined space is defined in the National Fuel Gas Code,ANSI Z223.1/NFPA 54 as "a space whose <br /> volume is less than 50 cubic feet per 1000 Btu/hr(4.8 m3 per kW per hour) of the aggregate input rating <br /> of all appliances installed in that space." Examples include a small room, closet, alcove, utility room, etc. <br /> A confined space must have two combustion air openings. Size the combustion air openings based on <br /> the BTU input for all gas utilization equipment in the space and the method by which combustion air is <br /> supplied. <br /> Using Indoor Air For Combustion: When using air from other room(s) in the building, the total volume of <br /> the room(s) must be of adequate volume (Greater than 50 cubic feet per 1000 Btu/hr). Combustion air <br /> openings between joining rooms must have at least 1 square inch of free area for each 1000 Btu/h, but <br /> not less than 100 square inches each. <br /> Using Outdoor Air For Combustion <br /> Outdoor air can be provided to a confined space through two permanent openings, one commencing <br /> within 12 in. (0.30 m)of the top and one commencing within 12 in. (0.30 m) of the bottom, of the confined <br /> space. The openings shall communicate to the outside by one of two ways. <br /> When communicating directly with the outdoors through horizontal ducts, each opening shall have <br /> a minimum free area of 1 in2/2000 Btu/hr(1100 mm2/kW) of total input rating of all appliances in the <br /> confined space. <br /> NOTE <br /> If ducts are used, the cross sectional area of the duct must be greater than or equal to the required <br /> If <br /> area of the openings to which they are connected. <br /> Rinnai Tankless Water Heater Installation and Operation Manual 44 <br />