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13
Installation and Service Manual
Figure 14 – Sidewall Combustion Air Inlet
Figure 15 – Air Inlet Cap for Sidewall Termination
To prevent recirculation of flue products from an adjacent vent cap
into the combustion air inlet, follow all applicable clearance
requirements in the latest edition of the National Fuel Gas Code
and/or CAN/CGA-B149 Installation Code and instructions in the
Installation and Service Manual.
You must install the combustion air inlet cap at least one foot
(0.30m) above ground level and above normal snow levels.
The point of termination for the combustion air inlet cap must be
at least 3 feet (0.91m) below the point of flue gas termination
(powered vent cap) if it is located within 10 feet (3.05m) of the flue
outlet from the powered vent cap. Make sure to properly install the
air inlet cap assembly on the air inlet pipe.
You must install the combustion air inlet cap and the powered vent
cap on the same wall and in the same pressure zone. Do not install
the combustion air inlet cap closer than 10 feet (3.05m) from an
inside corner of an L-shaped structure.
Vertical Rooftop Air Inlet
Use the vertical air inlet terminations available from the pool heater
manufacturer, recommended and/or supplied by the vent
manufacturer, or use two 90° elbows as described on
page 24.
Figure 16 – Roof Top Combustion Air Inlet
Clearances
You must locate the air inlet termination elbow at least 12" (30cm)
above the roof or above normal snow levels.
If the air inlet cap is within a 10 foot (3.05m) radius of the flue
outlet, the point of termination for the combustion air inlet cap
must be at least 3 feet (0.91m) below the point of flue gas
termination (vent cap).
Do not install the combustion air inlet cap closer than 10 feet
(3.05m) from an inside corner of an L-shaped structure.
Combined Air Inlet Points
The air inlet pipes from multiple pool heaters can be combined to
a single common connection if the common air inlet pipe has a
cross sectional area equal to or larger than the total area of all air
inlet pipes connected to the common air inlet pipe.
Example: Two 10" air inlet pipes (78.5 in
2
area each) have a total
area of 157 in
2
and will require a 15" (176.7 in
2
area) common air
inlet pipe.
The air inlet point for multiple pool heater air inlets must be
provided with an exterior opening which has a free area equal to or
greater than the total area of all air inlet pipes connected to the
common air inlet. This exterior opening for combustion air must
connect directly to the outdoors. The total length of the combined
air inlet pipe must not exceed a maximum of 50 (15.2m) equivalent
feet. Subtract 5 feet (1.5m) for each 90° elbow in the air inlet pipe.
You must deduct the restriction in the area provided by any screens,
grills or louvers installed in the common air inlet point. These are
common on the sidewall air inlet openings. Screens, grills or louvers
installed in the common air inlet can reduce the free area of the
opening from 25% to 75% based on the materials used.