Series UAG
Page 26
Nov 11, 2015
Venting / Combustion Air Ducting
Combustion Air Supply
•
An outside combustion air supply is strongly recommended.
•
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 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 23: Installation of Outside Air as supply for Combustion
Air F
low
Dire
ctio
n
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, chain links,
and turnbuckles or any open connection.
