L o c h i n v a r
D E S I G N E R
’
S G U I D E E F F I C I E N C Y
+
W A T E R H E A T E R
6 1 5 - 8 8 9 - 8 9 0 0
5
If a single combustion air opening is provided to
bring combustion air in directly from the outdoors,
the opening
MUST
be sized based on a
minimum free area of one square inch per
3000 Btu/hr (7 cm
2
per kW). This opening
MUST
be located within 12
”
(30 cm) of
the top of the enclosure.
CONTAMINANTS
Combustion air drawn from an interior or
exterior space
MUST
be free of any chemical
fumes which could be corrosive to the water
heater.
Burning chemical fumes results in the formation
of corrosive acids which attack the water
heater and cause improper combustion and
premature failure of the water heater and vent.
These fumes are often present in areas where
refrigerants, salts, and solvents are used.
Therefore, be aware of swimming pool
equipment, water softening, and cooling
system placement.
VENTING
General
Vent installations for connection to gas vents or
chimneys should be in accordance with Part 7,
“Venting of Equipment”, of the latest edition of
the National Fuel Gas Code, ANSI Z223.1, or
applicable provisions of the local building
codes.
The connection from the appliance vent to the
stack
MUST
be as direct as possible and
sized correctly, using the proper vent table.
The horizontal breaching of a vent
MUST
have at least 1/4
”
rise per linear foot.
The horizontal portions shall also be supported
for the design and weight of the material
employed to maintain clearances, prevent
physical damage and separation of joints.
The connection from the appliance vent to the
stack or vent termination outside the building
MUST
be made with listed Type “B” double
wall vent (or equivalent) for conventional vent
applications.
When utilizing direct vent capabilities,
connections
MUST
be made with AL29-4C
stainless steel (or equivalent) vent material.
Material should be sized according to vent sizing tables
(FAN column) in the latest edition of the National Fuel
Gas Code.
4.
CAUTION!
Under no circumstances should the
equipment room be under a negative pressure
when atmospheric combustion equipment is
installed in the room.
(FIG. 5) COMBUSTION AIR FROM A
SINGLE OPENING
NOTE:
The weight of the
venting system MUST
NOT rest on the water
heater. It should be
properly supported.
WARNING
Vent connectors serving
gas appliances, which
operate under a
negative vent pressure,
shall not be connected
into any portion of
mechanical draft
systems operating under
positive vent pressure.
