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31-5000726 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 11.
The NF96UV 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 or ventilated attic or crawlspace
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 9 and Table 10A through Table 10C. Count all elbows
inside and outside the home. Table 9 lists the minimum
vent pipe lengths permitted. Table 10A through Table 10C
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 12.
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.
NOTE:
The exhaust collar on all models is sized to
accommodate 2” Schedule 40 vent pipe. In horizontal
applications, any transition to exhaust pipe larger than 2”
must be made in vertical runs of the pipe. Therefore a 2”
elbow must be added before the pipe is transitioned to
any size larger than 2”. This elbow must be added to the
elbow count used to determine acceptable vent lengths.
Contact the Application Department for more information
concerning sizing of vent systems which include multiple
pipe sizes.
If this unit is being installed in an application with
combustion air coming in from a space serviced by an
exhaust fan, power exhaust fan, or other device which
may create a negative pressure in the space, take care
when sizing the inlet air opening. The inlet air opening
must be sized to accommodate the maximum volume
of exhausted air as well as the maximum volume of
combustion air required for all gas appliances serviced
by this space.
CAUTION
Ventilation Louvers
Inlet Air
(Minimum 12 in.
(305mm) above
Attic Floor)
Roof Terminated
Exhaust Pipe
Furnace
*Intake Debris
Screen
(Provided)
* See Maximum Vent Lengths table
NOTE-The inlet and outlet air openings shall each have a
free area of at least one square inch per 4,000 Btu (645mm
2
per 1.17kW) per hour of the total input rating of all equipment
in the enclosure.
Figure 19. Equipment in Confined Space
(Inlet Air from Ventilated Attic and Outlet Air to
Outside)
Roof Terminated
Exhaust Pipe
Furnace
Ventilation
Louvers
(Crawl Space)
*Intake Debris Screen Provided
Inlet Air
Minimum
12 in. (305mm)
above Crawl
Space Floor
Coupling or
3 in. to 2 in.
Transition
(Field Provided)
* See Maximum Vent Lengths table
NOTE-The inlet and outlet air openings shall each have a
free area of at least one square inch per 4,000 Btu (645mm
2
per 1.17kW) per hour of the total input rating of all equipment
in the enclosure.
Figure 20. Equipment in Confined Space
(Inlet Air from Ventilated Crawl Space and Outlet Air
to Outside)
