14
L o c h i n v a r
D E S I G N E R
’
S
G U I D E
P O W E R
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F I N
W A T E R
H E A T E R
6 1 5 - 8 8 9 - 8 9 0 0
Combined Combustion Air Inlet Points
for DirectAire Systems Only
The air inlet pipes from multiple appliances
can be combined into a single common
connection if the common air inlet pipe has
a cross sectional area equal to, or greater
than, the total area of all air inlet pipes
connected to the common air inlet pipe.
The air inlet point for multiple units 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.
You must deduct the restriction in area
provided by any screens, grills or louvers
installed in the common air inlet point.
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.
DirectAire Vertical
DirectAire Vertical vent systems are installed
with the flue terminating at the rooftop and
a separate combustion air inlet pipe at the
sidewall to draw air from the outdoors. The
flue outlet and combustion air inlet terminate
in different pressure zones.
The maximum installed length of the
combustion air inlet pipe and positive
pressure flue gas vent pipe must not
exceed 50 equivalent feet (15.2m) in
length per pipe.
EXCEPTION: For negative draft models
(PF0501-1300) the maximum installed
length of the flue gas vent pipe from the
appliance to the termination cap is limited
only by the requirement to maintain a
negative draft within the specified range
of 0.2 to 0.8 inches of water column.
The flue and air inlet sizes for DirectAire
Vertical systems with Sidewall Air Inlet are
listed in TABLE E. This venting option uses a
vent termination constructed from materials
purchased locally by the installer and a
sidewall air inlet purchased from the
manufacturer. The part numbers for the
required sidewall air inlet cap kit are listed
in TABLE D.
Lochinvar
(TABLE E) – FLUE & COMBUSTION
AIR PIPE SIZES
MODEL
AIR
NUMBER
FLUE
INLET
PF0501
7"
5"
PF0751
9"
5"
PF1001
10"
6"
PF1300
12"
6"
PF1500
8"
6"
PF1700
8"
8"
PF2000
10"
8"
(FIG. 13) DIRECTAIRE VERTICAL W/SIDEWALL AIR INLET
EXAMPLE OF
COMBINED AIR
INLET SIZING:
Two 5" (12.7cm) air inlet
pipes, 19.63 in² (126.6
cm²) in free area each,
have a total combined
free area of 39.26 in²
(253.3 cm²). These two
pipes require an 8" (20.3
cm) common air inlet
pipe, with 50.26 in²
(324.3 cm²) of free area.
