508134-01
Issue 2045
Page 26 of 56
Vent Piping Guidelines
NOTE:
Allied has approved the use of DuraVent
®
and
Centrotherm manufactured vent pipe and terminations as
an option to PVC. When using the PolyPro
®
by DuraVent
or InnoFlue
®
by Centrotherm venting system the vent
pipe requirements stated in the unit installation instruction
– minimum & maximum vent lengths, termination
clearances, etc. – apply and must be followed. Follow
the instructions provided with PoyPro by DuraVent and
InnoFlue by Centrotherm venting system for assembly
or if requirements are more restrictive. The PolyPro by
Duravent and InnoFlue by Centrotherm venting system
must also follow the uninsulated and unconditioned space
The A93DF1E / 92G1DFE can be installed as either a
Non-Direct Vent or a Direct Vent gas central furnace.
NOTE:
In Non-Direct Vent installations, combustion air is
taken from indoors and flue gases are discharged outdoors.
In Direct Vent installations, combustion air is taken from
outdoors and flue gases are discharged outdoors.
Intake and exhaust pipe sizing -- Size pipe according
to Table 10 and Table 11A through Table 11B. Count all
elbows in side and outside the home. Table 10 lists the
minimum vent pipe lengths permitted. Table 11A through
Table 11B lists the maximum pipe lengths permitted.
Regardless of the diameter of pipe used, the standard roof
and wall terminations described in section Exhaust Piping
Terminations should be used. Exhaust vent termination
pipe is sized to optimize the velocity of the exhaust gas as
it exits the termination. Refer to Table 13.
In some applications which permit the use of several
different sizes of vent pipe, a combination vent pipe may
be used. Contact Allied Technical Services Department for
assistance in sizing vent pipe in these applications.
NOTE:
It is acceptable to use any pipe size which fits
within the guidelines allowed in Table 11A or Table 11B.
NOTE:
All horizontal runs of exhaust pipe must slope back
toward unit. A minimum of 1/4” (6mm) drop for each 12”
(305mm) of horizontal run is mandatory for drainage.
NOTE:
Exhaust pipe MUST be glued to furnace exhaust
fittings.
NOTE:
Exhaust piping should be checked carefully to
make sure there are no sags or low spots.
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups and
may block the terminations.
IMPORTANT
Capacity
Min. Vent Length*
045, 070, 090
15 ft or 5 ft plus 2 elbows or
10 ft plus 1 elbow
*Any approved termination may be added to the minimum
length listed.
Table 10. Minimum Vent Pipe Lengths
Use the following steps to correctly size vent pipe diameter.
045, 070,
090
Standard or
Concentric?
See Table 9
Intake or
Exhaust?
1-1/2”, 2”,
2-1/2”
or 3”
Furnace capacity?
1
Which termination?
2
Which needs most
elbows?
3
How many?
4
Desired pipe size?
5
What is the altitude?
6
Use Table 11A and
Table 11B to find max
pipe length.
7
Figure 21. Vent Pipe Diameter Sizing