Series TA/TX/TXR
Page 28
Jan 07, 2015
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” linear 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 27: Installation of Outside Air as supply for Combustion
Air
Flow
Dir
ec
tion
Flex Duct
To Outside Air:
Directly to Outside
or to Common
Ductwork
from Blower
12"
Max.
for all Flex
Duct
Note:
Do not use flex duct
to form an elbow!
Note:
Close all open ended "S" hooks, chain links,
and turnbuckles or any open connection.
