Lochinvar GAS HEATER FOR COMMERICAL POOL APPLICATIONS - Manual (Page 13)

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
Installation and Service Manual
13