John Wood Commercial - AJWS - Manual (Page 6)

• Exhaust gas vents must be installed with U.L.listed type
B vent pipe according to the vent manufacturer’s instruc-
tions and the terms of its listing.
• Single wall vent connectors must have 152mm (6 in) of
clearance from unprotected combustible surfaces.
• If sidewall venting is necessary, a power vent kit is
required. For availability contact 1-888-479-8324.
• Vents that run through unconditioned spaces where
below freezing temperatures are expected should be
properly insulated to prevent freezing.
• Existing vent systems must be inspected for obstructions,
corrosion and proper installation.
• Vents must be connected to the water heater’s drafthood
by a certified vent connector or by directly originating at
the drafthood opening.
• Some models are shipped with a vent reducer. The vent
reducer can be installed directly to the drafthood if the
existing vent system is adequately sized to support the
exhaust gases.
• Vertical gas vents must terminate with a listed cap or
other roof assembly and be installed according to their
manufacturer’s instructions.
• Horizontal vent connections must have an upward slope
of at least 21mm per metre (1/4 in per foot).
• Gas vents must be supported to prevent damage, joint
separation, and maintain clearances to combustible
materials.
• Vent connection joints should be fastened by sheet metal
screws or by other approved methods.
• Vent and vent connectors should have adequate support
to keep weight off the drafthood.
All pipe, fittings, and procedures must conform to American
National Standard Institute and American Society for Testing
and Materials (ANSI/ASTM) standards in the United States.
Important: If you lack the necessary skills required to prop-
erly install this venting system, you should not proceed, but
get help from a qualified service technician.
Air Requirements
General
Where an exhaust fan or any other air consuming appliance
(Eg. Clothes dryer, furnace, etc.) is installed in the same
space as the water heater, sufficient air openings must be
available to provide fresh air when all appliances are oper-
ating simultaneously.
The area in which the heater is located is classified as either
“an unconfined space” or “a confined space”.
An unconfined space is defined as a space having a volume
not less than 50 cubic feet per 1000 BTU/hour (4.8 cubic
meters per kilowatt) of combined input rating of all appli-
ances using the space. Adjacent open rooms may be includ-
ed as part of the unconfined space. There shall be no
closeable doors between these rooms. An example of
this is an open basement.
A confined space is one smaller than described above. Air
shall be supplied through permanent openings as described
in Figure 2. At no time shall an air opening have a dimen-
sion of less than 76mm (3 in) and at no time shall any top
opening be lower than the top of the water heater.
For buildings that are not well sealed (do not have tight fit-
ting doors and windows) natural air infiltration may provide
sufficient air required for combustion and ventilation. For
buildings using tight construction (newer and renovated
structures), the air supply shall be introduced from the out-
doors, regardless of whether the space is confined or
unconfined.
Combustion Air “Supply” Ducts
Air supply ducts shall be of galvanized steel or equivalent
corrosion resistant material. A single air duct may not be
substituted when required for upper and lower air openings.
Horizontal upper combustion air ducts shall not slope
downward toward the air inlet.
Louvers and Grills
Openings for air supply ducts must provide free unobstruct-
ed air movement. Louver and grill openings must be sized
to ensure that the FREE OPEN AREA is never less than the
area of the air duct.
LOCATION:
The location for top and bottom openings are as follows;
For U.S. installations: The top opening shall commence
within 305mm (12 in) of the top of space and the bottom
opening shall commence within 305mm (12 in) of the bot-
tom of the enclosure.
For Canadian installations: The top opening shall be
located as close to the ceiling as practical but never lower
than the relief opening of the lowest draft control device.
The bottom opening shall be located neither more than
457mm (18 in), nor less than 152mm (6 in), above floor
level.
6
An adequate air supply shall be provided for
combustion and ventilation of this water
heater.
An insufficient supply can result in poor
combustion and possible sooting of the
burner, combustion chamber, or flue pas-
sageway. This may present a potential fire
hazard or create a serious health hazard by
producing carbon monoxide.
WARNING