507762-01
Issue 1907
Page 17 of 46
Vent Piping Guidelines
NOTE:
Allied Air 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 95G1UHEX 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 4 and Table 5. Count all elbows inside and outside
the home. Table 4 lists the minimum vent pipe lengths
permitted. Table 5 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 8.
PVC Exhaust Pipe
Vent Adaptor
Furnace
Exhaust Coupling
Furnace Top Panel
Top Band
Bottom Band
Figure 23. Appliance Adaptor to Exhaust Coupling
In some applications which permit the use of several
different sizes of vent pipe, a combination vent pipe may
be used. Contact the Allied Air Application 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.
NOTE - Exhaust pipe MUST be glued to furnace exhaust fittings.
NOTE -
ward unit. A minimum of 1/4” (6mm) drop for each 12” (305mm)
of horizontal run is mandatory for drainage.
NOTE - Exhaust piping should be checked carefully to make
sure there are no sags or low spots.
Exhaust Pipe
Horizontal
Gas Furnace
12” Min.
12” Max.
Figure 24. Horizontal Installation Offset Requirements
95G1UHEX Model
Min. Vent Length*
040, 060, 080, 100
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 4. 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