Venting Methods; Installation Of Standard Indoor Venting; Horizontal - LG GEN2 Series Installation And Operation Manual

Venting Methods

There are three venting methods for indoor mounted
units. For each method, the units can be vented
horizontally through an exterior wall or vertically
through the roof. Specific venting instructions are
provided for each method and shown in the following
pages. Construct the vent system as shown in these
instructions. Refer to your unit specific submittal to
determine the applicable venting option.
The venting method options are:
Standard Indoor Venting
• uses building air for combustion
• vents exhaust to outdoors
• one exterior roof or wall penetration
Separated Combustion Concentric Venting
• uses outside air for combustion
• vents exhaust to outdoors
• one exterior roof or wall penetration
Separated Combustion 2-Pipe Venting
• uses outside air for combustion
• vents exhaust to outdoors
• two exterior roof or wall penetrations
For each method, the units can be vented horizontally
through an exterior wall or vertically through the roof.
Refer to the specific venting instructions for your
unit. Construct the vent system as shown in these
instructions.

Installation of Standard Indoor Venting

Standard indoor venting uses one penetration through
an exterior wall or roof for venting the flue exhaust.
The combustion air is supplied from the air inside the
building. Units must not be installed in a potentially
explosive, flammable, or corrosive atmosphere. To
prevent premature heat exchanger failure, do not locate
unit where chlorinated, halogenated or acid vapors are
present.
When units are installed in tightly sealed buildings,
provisions should be made to supply an adequate
amount of infiltration air from the outside. The rule of
thumb is that an opening of one square inch should be
provided for every 1000 BTUs per hour of input rating.
Vent terminals must be used. Construct the vent
system as shown in the drawings. Reference the Vent
Pipe Diameter table and Exhaust Vent Pipe table for
additional details.
NOTE
A = 12 inch minimum
Standard Indoor Venting - Horizontal
Standard Indoor Venting - Vertical
Vent Pipe Diameter
Select the vent pipe
diameter. Use only the
specified pipe diameter.
Installing Exhaust
Vent Pipe
Install the vent pipe with a minimum downward slope
(from the unit) of 1/4-inch per foot (horizontal venting
only). Securely suspend the pipe from overhead
structures at points no
greater than 3 feet apart.
The minimum vent length
is 5 feet for horizontal
and 10 feet for vertical.
The maximum vent
length is 70 feet. The
total equivalent vent length must include elbows. The
equivalent length of a 4 inch elbow is 6 feet and the
equivalent length of a 6 inch elbow is 10 feet.
Attach the vent terminal to the end of the exhaust pipe.
Exterior
Wall
Pitch vent pipe
downward
from furnace
¼ inch per foot A
Air Inlet Exhaust
Vent
Terminal
Exhaust Vent
Terminal
Air Inlet
Standard Indoor Venting
Vent Pipe Diameter
Furnace Size Exhaust Pipe
(MBH) Diameter (inches)
75-175 4
200-400 6
Standard Indoor Venting
Exhaust Vent Pipe
Vent Minimum Maximum
Length (feet) (feet)

Horizontal

5 70
Vertical 10 70