If replacing a furnace which was
commonly vented with another gas appliance, the size
of the existing vent pipe for that gas appliance must be
checked. Without the heat of the original furnace flue
products, the existing vent pipe is probably oversized for
the single water heater or other appliance. The vent
should be checked for proper draw with the remaining
appliance.
REPLACING FURNACE THAT WAS PART OF A
COMMON VENT SYSTEM
CHIMNEY
OR GAS
VENT
(Check sizing
for water
heater only)
FURNACE
(Replaced)
WATER
HEATER
OPENINGS
(To Adjacent
Room)
FIGURE 18
Exhaust Piping (FIGURE 19, FIGURE 20, FIGURE 22
and FIGURE 23)
-
1 -
2 -
4 -
NOTE - PVC / ABS / NORYL transition solvent
cement WELD-ON 4052 (or equivalent) must be
used for connecting PVC exhaust pipe to NORYL
furnace exhaust coupling.
-
Furnace
Top Band
(torque to 40in-lbs)
PVC
Exhaust Pipe
Top Panel
Flue Coupling To Exhaust Coupling
Bottom Band
(torque to 40in-lbs)
Flue Couplig
Furnace
Exhaust Coupling
FIGURE 19
CAUTION
Do not discharge exhaust into an existing stack
or stack that also serves another gas appliance. If
vertical discharge through an existing unused stack
is required, insert PVC pipe inside the stack until the
end is even with the top or outlet end of the metal
stack.
CAUTION
The exhaust vent pipe operates under positive
pressure and must be completely sealed to prevent
leakage of combustion products into the living
space.
Vent Piping Guidelines
NOTE - Lennox has approved the use of DuraVent
®
and
Centrotherm manufactured vent pipe and terminations
as an option to PVC. When using the PolyPro
®
by Du-
raVent or InnoFlue
®
by Centrotherm venting system the
vent pipe requirements stated in the unit installation in-
struction – minimum & maximum vent lengths, termination
clearances, etc. – apply and must be followed. Follow the
instructions provided with PoyPro by DuraVent and Inno-
Flue by Centrotherm venting system for assembly or if re-
quirements 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 23.
The SL297UHNV is to be installed as a Direct Vent gas
central furnace.
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