Lennox SIGNATURE SLP99DFV Installation Instructions Manual page 19

TRANSITION
Exhaust
DO NOT transition
from larger to smaller
pipe in horizontal runs
of exhaust pipe.
Flue Coupling
The provided flue coupling must be attached to the exhaust
coupling on the furnace top panel. Use provided bands. See
steps below and FIGURE 22.
1 - Remove the caution tag from the flue coupling.
2 - Fully insert flue coupling with both bands loosely
attached on the furnace exhaust coupling.
3 - Insert PVC exhaust pipe through flue coupling. Ensure
vent pipe is fully seated into exhaust coupling.
4 - Tighten both top and bottom bands (do not use glue
or silicone to attach) to 40in-lbs.
Flue Coupling To Exhaust Coupling
PVC
Exhaust Pipe
Top Band
(torque to 40in-lbs)
Bottom Band
(torque to 40in-lbs)
FIGURE 22
TYPICAL PIPE CONNECTIONS
070 Only
1−1/2"
2"
2"
* When transitioning up in pipe size, use the shortest length of 2" PVC pipe possible.
Flue Couplig
Furnace
Exhaust Coupling
Furnace
Top Panel
2"
2"
2"
or
3"
TRANSITION
DO NOT transition from smaller
*2"
to larger pipe size in horizontal
runs of exhaust pipe.
NOTE − Exhaust pipe and intake pipe must be the same diameter.
FIGURE 21
Page 19
2"
Exhaust
INTAKE
EXHAUST
TOP VIEW