A.O. Smith BTH 120 - 250 - Manual (Page 6)

6
UNCONFINED SPACE
In buildings of conventional frame, brick or stone construction, unconfined
spaces may provide adequate air for combustion and ventilation.
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 and ventilation must be
obtained from outdoors. The installation instructions for confined spaces
in tightly constructed buildings must be followed to ensure adequate air
supply.
CONFINED SPACE
When drawing combustion 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 OF THE ENCLOSURE
TOP AND ONE IN OR WITHIN 12 INCHES OF THE ENCLOSURE BOTTOM.
Each opening shall have a free area of at least one square inch per 1000
Btuh of the total input of all appliances in the enclosure, but not less than
100 square inches.
If the confined space is within a building of tight construction, air for
combustion and ventilation must be obtained from outdoors. When directly
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 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 of the total input of all appliances in the enclosure.
CHEMICAL VAPOR CORROSION
WARNING
CORROSION OF THE FLUE WAYS AND VENT SYSTEM MAY OCCUR IF AIR
FOR COMBUSTION CONTAINS CERTAIN CHEMICAL VAPORS. SUCH
CORROSION MAY RESULT IN FAILURE AND RISK OF ASPHYXIATION.
Spray can propellants, cleaning solvents, refrigerator and air conditioning
refrigerants, swimming pool chemicals, calcium and sodium chloride, waxes,
and process chemicals are typical compounds which are potentially
corrosive.
PRODUCTS OF THIS SORT SHOULD NOT BE STORED NEAR THE HEATER.
ALSO, AIR WHICH IS BROUGHT IN CONTACT WITH THE HEATER SHOULD
NOT CONTAIN ANY OF THESE CHEMICALS. IF NECESSARY,
UNCONTAMINATED AIR SHOULD BE OBTAINED FROM REMOTE OR OUTSIDE
SOURCES.
VENTING
WARNING
THE INSTRUCTIONS IN THIS SECTION ON VENTING MUST BE FOLLOWED
TO AVOID CHOKED COMBUSTION OR RECIRCULATION OF FLUE GASES.
SUCH CONDITIONS CAUSE SOOTING OR RISKS OF FIRE AND
ASPHYXIATION.
Heater must be protected from freezing downdrafts during shutdown periods.
WARNING
NEVER OPERATE THE HEATER UNLESS IT IS VENTED TO THE OUTDOORS
AND HAS ADEQUATE AIR SUPPLY TO AVOID RISKS OF IMPROPER
OPERATION, FIRE, EXPLOSION OR ASPHYXIATION.
VENT PIPE TERMINATION
NOTE: Before installing venting, determine place of vent pipe termination.
See Figure 6 before proceeding.
CAUTION
DO NOT TERMINATE THE VENTING WHERE NOISE FROM THE EXHAUST OR
INTAKE WILL BE OBJECTIONABLE. THIS INCLUDES LOCATIONS CLOSE TO
OR ACROSS FROM WINDOWS AND DOORS. AVOID ANCHORING THE
VENT AND INTAKE PIPES DIRECTLY TO FRAMED WALLS, FLOORS OR
CEILINGS UNLESS RUBBER ISOLATION PIPE HANGERS ARE USED. THIS
PREVENTS ANY VIBRATIONS FROM BEING TRANSMITTED INTO THE LIVING
SPACES.
WARNING
DO NOT USE THIS APPLIANCE IF ANY PART HAS BEEN UNDER WATER.
IMMEDIATELY CALL A QUALIFIED SERVICE TECHNICIAN TO INSPECT THE
APPLIANCE AND TO REPLACE ANY PART OF THE CONTROL SYSTEM
AND ANY GAS CONTROL WHICH HAS BEEN UNDER WATER.
CLEARANCES
These heaters are approved for installation on combustible flooring in an
alcove when the minimum clearances from any combustion construction
are followed as indicated in Figure 4.
In all installations the minimum combustible clearances from any vent piping
shall be 0". Vent piping passing through a combustible wall or ceiling must
be a continuous run (no joints).
A service clearance of 24" should be maintained from serviceable parts
such as relief valves, flue baffles, flue damper devices, thermostats,
cleanout openings or drain valves.
Always disconnect electrical power before servicing the unit
FIGURE 4
*ILLUSTRATION OF MINIMUM COMBUSTIBLE CLEARANCES IN AN
ALCOVE
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 MAINTENANCE section for details of tank cleanout procedure.
AIR REQUIREMENTS
KEEP APPLIANCE AREA CLEAR AND FREE OF COMBUSTIBLE MATERIALS,
GASOLINE AND OTHER FLAMMABLE VAPORS AND LIQUIDS.
DO NOT OBSTRUCT THE FLOW OF COMBUSTION AND 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
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.
MECHANICAL EXHAUSTING OF ROOM AIR
Where an exhaust fan is installed 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 HEATER’S
VENTING SYSTEM, CAUSING POOR COMBUSTION. SOOTING MAY RESULT
IN SERIOUS DAMAGE TO THE HEATER AND RISK OF FIRE OR EXPLOSION.
IT CAN ALSO CREATE A RISK OF ASPHYXIATION.