Series
LTA/LTX/LTXR
Page
31 Nov./21/12
Venting / Combustion Air Ducting
Combustion Air Supply (Optional)
•
An outside combustion air supply is strongly recommended if the building space encloses a
negative pressure due to exhaust etc. or if the building contains materials which would expose the
heater to halogenated hydrocarbon atmospheres.
•
The outside air terminal must be of an approved type, and should be located at an elevation equal
to or below the vent terminal elevation to prevent back-venting of flue gases into the burner
compartment.
•
Install single wall pipe or PVC pipe and fittings with a 12-inch linier section of flexible duct to
allow movement of the heater. Do not use flexible duct throughout the entire length of fresh air
duct. This may cause nuisance air switch tripping.
Figure 30: Installation of Outside Air as supply for Combustion
Air F
low
Di
rec
tion
Flex Duct
To Outside Air:
Directly to Outside
or to Common
Ductwork
from Blower
12"
Max.
for all Flex
Duct
