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31-5000729 Rev. 0
Vent Piping Guidelines
NOTE:
GE Appliances 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 criteria listed in Table
12.
The NF96DS can be installed as either a Non-Direct Vent
or a Direct Vent gas central furnace.
NOTE:
In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors. In
Non-Direct Vent installations, combustion air is taken from
indoors or ventilated attic or crawlspace and flue gases are
discharged outdoors.
Intake and exhaust pipe sizing -- Size pipe according to
Table 9 and Table 10A through Table 11B. Count all elbows
in side and outside the home. Table 9 lists the minimum vent
pipe lengths permitted. Table 10A 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 GE Appliances Technical Services Department for
assistance in sizing vent pipe in these applications.
Capacity
Min. Vent Length*
045, 070, 090, 110
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 9. Minimum Vent Pipe Lengths
Do not use screens or perforated metal in exhaust or
intake terminations. Doing so will cause freeze-ups and
may block the terminations.
IMPORTANT
NOTE:
It is acceptable to use any pipe size which fits within
the guidelines allowed in Table 10A through 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.
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 10 through
Table 11 to find max
pipe length.
7
Figure 21. Vent Pipe Diameter Sizing
