U.S. REQUIREMENTS
Ratings specified by manufacturers for most appliances apply for elevations up to 2000 feet (610 m). For elevations above 2000 feet (610 m), ratings must be reduced at the rate of 4% for each 1000 feet (305 m) above sea level. For example, if a heater is rated at 65,000 Btuh (19 Kw) at sea level, to rate the heater at 4000 feet (1219 m), you subtract 4 (once for each thousand feet) x.04 (4% input reduction) x 65,000 (original rating) from the original rating. Therefore, to calculate the input rating at 4,000 feet (1219 m): 4 x .04 x 65,000 = 10,400 Btuh (3.0 Kw), 65,000 (19 Kw) - 10,400 (3.0 Kw) = 54,600 Btuh (16 Kw). At 6000 feet (1829 m) the correct input rating should be 49,400 Btuh (14.5 Kw).
CANADIAN REQUIREMENTS
Appliances with inputs up to and including 400,000 BTU must be factory equipped with orifices for operation at specific elevations. Standard (sea level) orifices permit operation up to 2000' (610 m) elevation. For operation between 2000' (610 m) and 4500' (1370 m) specify "HIGH ALTITUDE OPERATION" when ordering the heater(s). For operation above 4500' (2370 m) consult factory before ordering.
Field conversion for operation at altitudes other than that specified on the heater rating plate is not permitted.
The input reduction is primarily achieved by reducing the size of the main burner orifices. To do this, the main burner orifices require replacement with orifices sized for the particular installation elevation. Correct orifice sizing and parts may be obtained from A.O. Smith Water Products Company. When ordering, be sure to state the model number and the altitude of the location where the water heater is being installed.
Upon completion of derating of the heater, adjustment to the gas pressure regulator may be required. See CHECKING THE INPUT section in this manual for inlet and manifold pressure requirements.
Also due to the input rating reduction required at high altitudes, the output rating of the appliance is reduced and should be compensated for in the sizing of the equipment for application.
CLEARANCES
These heaters are approved for installation on combustible flooring in a closet having a ceiling 18" (457 mm) above top cover and with clearances to combustible construction of 6" (152 mm) from flue or vent connector, 1" (25 mm) at the sides and rear and 4" (102 mm) to front to prevent a possible fire hazard condition. A minimum of 4" (101.6 mm) shall be allowed for installation of serviceable parts.
HARD WATER
Where hard water conditions exist, water softening or the threshold type of water treatment is recommended. This will protect the dishwashers, coffee urns, water heaters, water piping and other equipment.
Contact your dealer or qualified service technician for more information on this product.
AIR REQUIREMENTS
REFER TO THE LATEST EDITION OF THE "NATIONAL FUEL GAS CODE" ANSI Z223.1/NFPA 54. FOR CANADA CONSULT CAN/CSA B149.1-00.
KEEP APPLIANCE AREA CLEAR AND FREE OF COMBUSTIBLE MATERIALS, GASOLINEAND OTHER FLAMMABLES, VAPORSAND LIQUIDS.
DO NOT OBSTRUCT THE FLOW OF COMBUSTION OR VENTILATING AIR.
WARNING
FOR SAFE OPERATION PROVIDE ADEQUATE AIR FOR COMBUSTION AND VENTILATION. AN INSUFFICIENT SUPPLY OF AIR WILL CAUSE RECIRCULATION OF COMBUSTION PRODUCTS RESULTING IN AIR CONTAMINATION THAT MAY BE HAZARDOUS TO LIFE. SUCH A CONDITION OFTEN WILL RESULT IN A YELLOW, LUMINOUS BURNER FLAME, CAUSING CARBONING OR SOOTING OF THE COMBUSTION CHAMBER, BURNERS AND FLUE TUBES AND CREATES A RISK OF ASPHYXIATION.
Where an exhaust fan is supplied in the same room with a heater, sufficient openings for air must be provided in the walls.
UNDERSIZED OPENINGS WILL CAUSE AIR TO BE DRAWN INTO THE ROOM THROUGH THE CHIMNEY, CAUSING POOR COMBUSTION. SOOTING MAY RESULT IN SERIOUS DAMAGE TO THE HEATER AND RISK OF FIRE OR EXPLOSION.
UNCONFINEDSPACE
In buildings of conventional frame, brick, or stone construction, unconfined spaces may provide adequate air for combustion, ventilation and draft hood dilution.
If the unconfined space is within a building of tight construction (buildings using the following construction: weather stripping, heavy insulation, caulking, vapor barrier, etc.), air for combustion, ventilation and draft hood dilution must be obtained from outdoors. The installation instructions for confined spaces in tightly constructed buildings must be followed to ensure adequate air supply.
CONFINEDSPACE
When drawing combustion and dilution air from inside a conventionally constructed building to a confined space, such a space shall be provided with two permanent openings, ONE IN OR WITHIN 12 INCHES (30.50 cm) OF THE ENCLOSURE TOP AND ONE IN OR WITHIN 12 INCHES (30.50 cm) OF THE ENCLOSURE BOTTOM. Each opening shall have a free area of at least one square inch per 1000 Btuh (2202.8 mm2/KW) of the total input of all appliances in the enclosure, but not less than 100 square inches (645 cm2).
If the confined space is within a building of tight construction, air for combustion, ventilation, and draft hood dilution must be obtained from outdoors. When directly communicating with the outdoors or communicating with the outdoors through vertical ducts, two permanent openings, located in the above manner, shall be provided. Each opening shall have a free area of not less than one square inch per 4000 Btuh (550.7 mm2/KW) of the total input of all appliances in the enclosure. If horizontal ducts are used, each opening shall have a free area of not less than one square inch per 2000 Btuh (1101.4 mm2/KW) of the total input of all appliances in the enclosure. For Canadian installations consult CAN/CSA B149.1-00.
COMBINATION WATER (POTABLE) HEATING AND SPACE HEATING
1.All piping components connected to this unit for space heating applications shall be suitable for use with potable water.
