5
Drain pans suitable for these heaters are available from your
distributor or A. O. Smith Water Products Company, 500 Tennessee
Waltz Parkway, Ashland City, TN 37015.
Water heater life depends upon water quality, water pressure and the
environment in which the water heater is installed. Water heaters are
sometimes installed in locations where leakage may result in property
damage, even with the use of a drain pan piped to a drain. However,
unanticipated damage can be reduced or prevented by a leak detector
or water shutoff device used in conjunction with a piped drain pan.
These devices are available from some plumbing supply wholesalers
and retailers, and detect and react to leakage in various ways:
• Sensors mounted in the drain pan that trigger an alarm or turn off
the incoming water to the water heater when leakage is detected.
• Sensors mounted in the drain pan that turn off the water supply
to the entire home when water is detected in the drain pan.
• Water supply shutoff devices that activate based on the water
pressure differential between the cold water and hot water pipes
connected to the water heater.
• Devices that will turn off the gas supply to a gas water heater
while at the same time shutting off its water supply.
For appliance installation locations with elevations above 2000'
(610m), refer to HIGH ALTITUDE INSTALLATIONS section of this
manual for input reduction procedure.
HIGH ALTITUDE INSTALLATIONS
WARNING
INSTALLATIONS ABOVE 2000' (610m) REQUIRE REPLACEMENT
OF THE BURNER ORIFICE IN ACCORDANCE WITH SECTION
8.1.2 OF THE NATIONAL FUEL GAS CODE (ANSI Z223.1). FOR
CANADIAN INSTALLATIONS CONSULT THE NATURAL GAS AND
PROPANE INSTALLATION CODE CAN/CSA-B149.1. FAILURE TO
REPLACE THE ORIFICE WILL RESULT IN IMPROPER AND
INEFFICIENT OPERATION OF THE APPLIANCE RESULTING IN
THE PRODUCTION OF INCREASED LEVELS OF CARBON
MONOXIDE GAS IN EXCESS OF SAFE LIMITS WHICH COULD
RESULT IN SERIOUS PERSONAL INJURY OR DEATH.
You should contact your gas supplier for any specific changes which
may be required in your area.
As elevation above sea level is increased, there is less oxygen per
cubic foot of air. Therefore, the heater input rate should be reduced
at high altitudes for satisfactory operation with the reduced oxygen
supply. Failure to make this reduction would result in an overfiring
of the heater causing sooting, poor combustion and/or unsatisfactory
heater performance.
U.S. REQUIREMENTS
Ratings specified by manufacturers for most appliances apply for
elevations up to 2000 feet (610m). For elevations above 2000 feet
(610m), ratings must be reduced at the rate of 4% for each 1000 feet
(305m) above sea level. For example, if a heater is rated at 75,100
Btu/Hr (22.0 kW) at sea level, to rate the heater at 4000 feet (1219m),
you subtract 4 (once for each thousand feet) x 0.04 (4% input
reduction) x 75,100 Btu/Hr (original rating) from the original rating.
Therefore, to calculate the input rating at 4000 feet (1219m): 4 x 0.04
x 75,100 Btu/Hr = 12,016 Btu/Hr (3.5 kW); 75,100 Btu/Hr (22.0 kW) -
12,016 Btu/Hr (3.5 kW) = 63,084 Btu/Hr (18.5 kW). At 6000 feet
(1829m) the correct input rating should be 57,076 Btu/Hr (16.7 kW).
CANADIAN REQUIREMENTS
Appliances with inputs up to and including 400,000 BTU (117.1 kwh)
must be factory equipped with orifices for operation at specific
elevations. Standard (sea level) orifices permit operation up to 2000'
(610m) elevation. For operation between 2000' (610m) and 4500'
(1370m) specify "HIGH ALTITUDE OPERATION" when ordering the
heater(s). For operation above 4500' (1370m) 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
recovery rating of the appliance is also 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 12" (30.5cm) above top cover and with
clearances to combustible construction of 6" (15.2cm) from flue or
vent connector, 0" (0cm) at the sides and rear and 4" (10.1cm) to
front to prevent a possible fire hazard condition. A minimum of 4"
(10.1cm) 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.
See PREVENTIVE MAINTENANCE section for details of tank
cleanout procedure.
AIR REQUIREMENTS
REFER TO THE CURRENT EDITION OF THE NATIONAL FUEL
GAS CODE ANSI Z223.1/NFPA 54.
KEEP APPLIANCE AREA CLEAR AND FREE OF COMBUSTIBLE
MATERIALS, GASOLINE AND OTHER FLAMMABLES, VAPORS
AND 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.
UNCONFINED SPACE
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