A.O. Smith BTH 300A Water Heater User Manual


 
7
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" (61 cm) should be maintained from
serviceable parts such as relief valves, thermostats, cleanout
openings, drain valves and venting connections.
Always disconnect electrical power before servicing the unit
*ILLUSTRATION OF MINIMUM COMBUSTIBLE CLEARANCES IN AN ALCOVE.
FIGURE 4.
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.
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 (31 cm) OF THE ENCLOSURE TOP AND ONE IN OR
WITHIN 12 INCHES (31 cm) OF THE ENCLOSURE BOTTOM.
Each opening shall have a free area of at least one square inch per
1000 Btuh (2,203mm
2
/kW) 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 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 (551mm
2
/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 (1,102mm
2
/kW) 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.