21
5.10 (3" /80 mm Only) Flexible Vent System
Flexible Pipe Vent Lengths
Boiler Size
125/150
Vent Size
3” [80 mm] Diameter Pipe
Minimum
Minimum
Maximum
Natalini
Exhaust
6 ft [1.8 m]
75 ft [22.8 m]
Intake
6 ft [1.8 m]
50 ft [15.2 m]
DuraVent
®
Exhaust
6 ft [1.8 m]
82 ft [24.9 m]
Intake
6 ft [1.8 m]
50 ft [15.2 m]
Centrotherm
Exhaust
6 ft [1.8 m]
52 ft [15.8 m]
Intake
6 ft [1.8 m]
50 ft [15.2 m]
Z-Dens
Exhaust
NA
NA
Intake
Single Wall Elbows - Equivalent Length
3" [80 mm]
45° bend
0.82 ft [0.25 m]
90° bend
1.64 ft [0.50 m]
•
Maximum vent lengths based on equivalent straight
runs only. Include rigid pipe and fittings in overall
equivalent length calculations.
• Flexible venting installations use single wall
polypropylene to pass flue gasses to base of chimney,
then flexible venting to get them to termination at the
top.
• Combustion air is not supplied through masonry
chimney. Combustion air must be from outside using 3"
[80 mm] single wall polypropylene.
• Position boiler to use minimum of rigid single wall
polypropylene venting to the chimney.
• Follow venting manufacturer's instructions on assembly
and clearances to maintain.
•
Avoid sharp bends in flexible venting.
FIGURE 5-24 - (3" / 80 mm Only) Flexible Venting
System CAN BE USED ON ALL SIZES
Combustion
Air
Vent Terminal
Flexible Vent
Rigid Vent
5 - COMBUSTION AIR AND VENT PIPING
NOTICE
Flexible vent systems shall only be run vertical.
Horizontal runs before adapting to flexible must be
rigid pipe.
240012564 REV A, [05/15/2019]