User Guide

16
AIR REQUIREMENTS
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.
For safe operation, an adequate supply of fresh
uncontaminated air for combustion and ventilation must
be provided.
An insufcient 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 ame, causing sooting of
the combustion chamber, burners, and ue tubes, and
creates a risk of asphyxiation.
Do not install the water heater in a conned space unless
an adequate supply of air for combustion and ventilation
is brought in to that space using the methods described
in Conned Space (page 16) that follows later in this
manual.
Never obstruct the ow 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 re or explosion and cause property damage, serious
bodily injury or death.
UNCONFINED SPACE
An unconned space is one in which the 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 unconned space.
Makeup air requirements for the operation of exhaust
fans, kitchen ventilation systems, clothes dryers and
replaces shall also be considered in determining the
adequacy of a space to provide combustion, ventilation
and dilution air.
UNUSUALLY TIGHT CONSTRUCTION
In unconned spaces in buildings, inltration may be
adequate to provide air for combustion, ventilation and
dilution of ue 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 that follows.
CONFINED SPACE
A conned space is one in which the volume is 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.
Openings must be installed to provide fresh air for
combustion, ventilation and dilution in conned spaces.
The required size for the openings is dependent on the
method used to provide fresh air to the conned space
and the total Btu/hr input rating of all appliances installed
in the space.
DIRECT VENT APPLIANCES
Appliances installed in a direct-vent conguration
that derives 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 conned 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,
sufcient 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 re 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 specied. Where the louver and grille design