Direct Venting - Lochinvar EW 150 Designer's Manual

This can result in incomplete combustion and
potentially hazardous levels of carbon
monoxide in the flue products.
COMBINED AIR INLET POINTS
The air inlet pipes from multiple water heaters
can be combined into 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.
The air inlet point for multiple water 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 feet
equivalent feet (15.2 m). 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.
The air inlet cap for the combined air supply from
multiple water heaters MUST be purchased or
fabricated in the field.
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

DIRECT VENTING

POSITIVE PRESSURE
A direct vent water heater uses a two pipe
system, one pipe for the flue products and one
pipe for the combustion air supply. The flue
CANNOT be combined with any other appliance
vent or common vent from multiple water heaters.
The vent on a direct vent system will have a
positive pressure in the flue, which requires all
vent joints and seams to be sealed gas-tight. The
flue from a direct vent system MUST have a
condensate drain with provisions to properly
collect and dispose of any condensate that may
occur in the venting system. Direct vent systems
require Category IV vent material with AL29-4C
approved stainless steel.
The air inlet pipe connects directly to the water
heater to supply combustion air. The air inlet pipe
MUST be sealed. Choose acceptable
combustion air pipe materials from those
specified in this section.
Approved material for air inlet pipes include:
PVC, CPVC or ABS (4", 5" or 6" I.D.), dryer
vent, and galvanized steel vent pipe with joints
and seams sealed.
The total equivalent length of the direct vent flue
pipe or the air inlet pipe MUST NOT exceed a
maximum of 50 equivalent feet (15.2 m) in length
for each pipe. Subtract 5 feet (1.5 m) for each
elbow in the vent pipe or air intake system.
+ 6 1 5 - 8 8 9 - 8 9 0 0
W A T E R H E A T E R
EXAMPLE OF
COMBINED AIR
INLET SIZING
Two 5" air inlet pipes
(19.6 in area each) have
2
a total area of 39.2 in 2
requiring an 8" (50.3 in 2
area) common air inlet
pipe.
1 1