22
Vent and Combustion Air Piping Installation Guidelines
1. The installer should install the vent / combustion air
piping working from the appliance to the piping termi-
nation. The piping should not exceed the lengths given
in Table 2 for either the vent or combustion air.
2. The installer should cut the pipe if required to the
appropriate lengths and deburr the inside and outside.
3. The installer should chamfer the outside of the pipe.
4. The installer should dry assemble the combustion
air system prior to assembling any joints to ensure
proper fit.
5. The pipe ends and fittings should be cleaned and
dried thoroughly prior to assembly of the joint.
6. Refer to vent manufactures instructions for proper
sealing of the vent system.
7. The installer should use perforated metal strap
hangers or equivalent pipe hangers to support the
piping. The hangers must be spaced at a maximum
of every 5 feet of horizontal or vertical run of piping.
A support must be placed near the appliance and
where the vent turns vertical. Do not penetrate any
part of the piping or vent system with fasteners.
8. The vent and combustion air piping should be sloped
continuously from the termination back to the appli-
ance with at least 1/4 inch drop per foot of run. Do not
allow any sags in the run of piping.
9.
Maintain minimum clearances per vent manufac-
ture’s instructions for both, combustible or non-com-
bustible materials. The installer must seal any wall,
floor or ceiling penetrations as per local code
requirements.
10. The vent piping does not require any insulation. The
installer may opt to insulate the vent piping in those
portions of the piping that pass through unheated
spaces such as crawl spaces or attics. In these
areas the installer may apply fiberglass insulation to
the outside of the vent pipe.
Table 2 references a long radius 90
º
elbow. For
each additional 90
º
elbow within the system, the
installer must reduce the maximum allowable
length by 7 feet. If a short radius 90
º
elbow is
used the maximum allowable length must be
reduced by 10 feet for each short radius 90
º
elbow. If a 45
º
elbow is used the maximum allow-
able length must be reduced by 3 feet for each
45
º
elbow.
It is recommended that the installer uses the
same number of elbows and length of piping on
the venting system and the combustion air inlet.
BEST PRACTICE
NOTICE
Direct Vent Installation of Vent/Air Piping
MODULATING
DELTA
Model
Feet
Elbows
Feet
Elbows
PG-150
PG-199
PG PLUS-150
PG PLUS-199
Maximum Allowable Vent or Combustion Air Piping Length
3 inch Diameter Vent or Combustion Air Piping
60
0
46
2
TABLE 2
