Air Requirements - State Water Heaters 301 Series Instruction Manual

AIR REQUIREMENTS

For safe operation an adequate supply of fresh uncontaminated
air for combustion and ventilation must be provided.
An insufficient supply of air can 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 sooting of the combustion chamber, burners and
flue tubes and creates a risk of asphyxiation.
Breathing Hazard - Carbon Monoxide Gas
Install water heater in accordance with
the Instruction Manual and NFPA 54 or
CAN/CSA-B149.1.
To avoid injury, combustion and ventilation
air must be taken from outdoors.
Do not place chemical vapor emitting
products near water heater.
Breathing carbon monoxide can cause brain damage or
death. Always read and understand instruction manual.
Do not install the water heater in a confined space unless an
adequate supply of air for combustion and ventilation is brought in
to that space using the methods described in the Confined Space
section that follows.
Never obstruct the flow of ventilation air. If you have any doubts
or questions at all, call your gas supplier. Failure to provide the
proper amount of combustion air can result in a fire or explosion
and cause property damage, serious bodily injury or death.
UNCONFINED SPACE
An Unconfined Space is one whose volume IS NOT LESS THAN
50 cubic feet per 1,000 Btu/hr (4.8 cubic meters per kW) of the
total input rating of all appliances installed in the space. Rooms
communicating directly with the space, in which the appliances
are installed, through openings not furnished with doors, are
considered a part of the unconfined space.
Makeup air requirements for the operation of exhaust fans,
kitchen ventilation systems, clothes dryers and fireplaces
shall also be considered in determining the adequacy of a
space to provide combustion, ventilation and dilution air.
UNUSUALLY TIGHT CONSTRUCTION
In unconfined spaces in buildings, infiltration may be adequate to
provide air for combustion, ventilation and dilution of flue gases.
However, in buildings of unusually tight construction (for example,
weather stripping, heavily insulated, caulked, vapor barrier, etc.),
additional air must be provided using the methods described in
the section that follows.
Confined Space
CONFINED SPACE
A confined space is one whose volume IS LESS THAN 50 cubic
feet per 1,000 Btu/hr (4.8 cm per kW) of the total input rating of
all appliances installed in the space.
Openings must be installed to provide fresh air for combustion,
ventilation and dilution in confined spaces. The required size for
the openings is dependent on the method used to provide fresh
air to the confined space AND the total Btu/hr input rating of all
appliances installed in the space.
DIRECT VENT APPLIANCES
Appliances installed in a Direct Vent configuration that derive all
air for combustion from the outdoor atmosphere through sealed
intake air piping are not factored in the total appliance input Btu/
hr calculations used to determine the size of openings providing
fresh air into confined spaces.
EXHAUST FANS
Where exhaust fans are installed, additional air shall be provided
to replace the exhausted air. When an exhaust fan is installed in
the same space with a water heater, sufficient openings to provide
fresh air must be provided that accommodate the requirements
for all appliances in the room and the exhaust fan. Undersized
openings will cause air to be drawn into the room through the water
heater's vent system causing poor combustion. Sooting, serious
damage to the water heater, and the risk of fire or explosion may
result. It can also create a risk of asphyxiation.
LOUVERS AND GRILLES
The free areas of the fresh air openings in the instructions that
follow do not take in to account the presence of louvers, grilles or
screens in the openings.
The required size of openings for combustion, ventilation and
dilution air shall be based on the "net free area" of each opening.
Where the free area through a design of louver or grille or screen is
known, it shall be used in calculating the size of opening required
to provide the free area specified. Where the louver and grille
design and free area are not known, it shall be assumed that wood
louvers will have 25% free area and metal louvers and grilles will
have 75% free area. Non motorized louvers and grilles shall be
fixed in the open position.
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