507762-01
Issue 1907
Page 29 of 46
Details of Exhaust Piping Terminations for Non-
Direct Vent Applications
Exhaust pipes may be routed either horizontally through
an outside wall or vertically through the roof. In attic
or closet installations, vertical termination through the
roof is preferred. Figure 44 and Figure 45 show typical
terminations.
1. Exhaust piping must terminate straight out or up as
shown. The termination pipe must be sized as listed
in Table 8.The specified pipe size ensures proper
velocity required to move the exhaust gases away
from the building.
2. On field supplied terminations for side wall exit,
exhaust piping may extend a maximum of 12 inches
(305mm) for 2” PVC and 20 inches (508mm) for 3”
(76mm) PVC beyond the outside wall.
3. If exhaust piping must be run up a side wall to position
above snow accumulation or other obstructions, piping
must be supported every 24 inches (610mm). When
exhaust piping must be run up an outside wall, any
reduction in exhaust pipe size must be done after the
final elbow.
4. Distance between exhaust pipe terminations on
multiple furnaces must meet local codes.
UNCONDITIONED
ATTIC SPACE
3” (76MM) OR
2” (51MM) PVC
PROVIDE SUPPORT
FOR EXHAUST LINES
12” (305MM)
ABOVE AVE.
SNOW
ACCUMULATION
SIZE PER EXHAUST PIPE
TERMINATION SIZE
REDUCTION TABLE
Figure 44. Non-Direct Vent Roof Termination Kit
(15F75 Or 44J41)
Crawl Space and Extended Horizontal Venting
Allied Air provides kit 51W18 (USA) or kit 15Z70 (Canada)
to install 2” or 3” PVC exhaust piping through the floor
joists and into the the crawl space. See Figure 46.
This kit can also be used as a supplemental drain for
installations with condensate run back in the vent pipe (ie.
long horizontal runs, unconditioned spaces, etc.).
STRAIGHT-CUT OR
ANGLE-CUT IN DIRECTION
OF ROOF SLOPE
SHOULDER OF FITTINGS
PROVIDE SUPPORT
OF PIPE ON TOP PLATE
EXTERIOR
PORTION OF
CHIMNEY
INSULATE
TO FORM
SEAL
SHEET
METAL TOP
PLATE
Minimum 12” (305MM)
above chimney top
plate or average snow
accumulation
* SIZE TERMINATION PIPE
PER EXHAUST PIPE TERMINATION
SIZE REDUCTION TABLE
NOTE
- Do not discharge exhaust gases directly into any
chimney or vent stack. If vertical discharge through an existing
unused chimney or stack is required, insert piping inside
chimney until the pipe open end is above top of chimney and
terminate as illustrated. In any exterior portion of chimney, the
exhaust vent must be insulated.
Figure 45. Non-Direct Vent Application Using Existing
Chimney
KIT 51W18 (USA)
Basement Floor
To Termination
1/2” PVC to
Code-Approved
Drain
24” max.
Downflow Furnace
Exhaust
KIT 15Z70 (Canada)
* Kit 51W18 is shown.
Figure 46. Venting in a Crawl Space
