33
Venting and Combustion Air Installation
Although the vent system is allowed to
pitch away from the unit, it is recom-
mended that the vent system pitches
toward the unit with a condensate drain
installed as close to the unit as possible.
Opting to pitch the vent system away
poses potential damage to the building
exterior or to the surrounding landscape
and/or potential risks of icing if conden-
sate is formed.
c. Penetration at the wall requires a
thimble.
d. Clearance to combustibles must be
maintained per the vent manufacturer’s
requirements. Refer to the vent manu-
facturer’s installation instructions for
additional details.
Maintain a minimum 2-inch clearance to
combustible wall and 1-inch clearance to
non-combustible in the absence of the
vent manufacturer’s recommended
clearance when penetrating a sidewall.
e. For a zero clearance concentric termi-
nation of the vent and combustion air
refer to the Horizontal Concentric,
Horizontal Single Wall Vent or
Horizontal Wall Thimble Kits.
There are two methods available for Direct
Venting - Horizontal:
Separate:
The vent and the combustion air
inlet are run together and exit the structure sep-
arately with different terminations. See Fig. 23,
page 37.
The combustion air inlet and the vent
termination must reside in the same
pressure zone area of the building for
proper operation of the appliance.
Combination:
The vent and combustion air ter-
minate at a single concentric point using the
Horizontal Concentric, Horizontal Single Wall
Vent or Horizontal Wall Thimble Kit. See Figs.:
22,22A and 22B, page 36.
Horizontal Wall Thimble Kit
-
Requires a 5 1/2 inch x 5 1/2 inch penetra-
tion through any type of wall.
-
Allows zero clearance at the wall penetration.
-
Maximum wall thickness is 11 inches.
-
The use of a termination elbow for the
venting system is not recommended when
using the Horizontal Wall Thimble Kit.
To prevent potential nuisance lock-outs
or flue gas recirculation it is recommend-
ed to terminate the vent with a horizon-
tal termination tee or side discharge vent
hood.
Excessive Horizontal Vent Runs
If maintaining the 1/4 inch per foot pitch
requirement creates clearance problems with
structural obstacles, i.e. low ceilings, the
installer may opt to installing the vent in a man-
ner that pitches up to a high point from the unit
and then pitches away from the high point to
the vent termination.
A condensate tee should be installed as close as
possible to the unit when venting in this manner.
BEST PRACTICES
NOTICE
NOTICE
BEST PRACTICE
