Maximum Vent/Air Intake Pipe Length - Vertical; Maximum Allowable Vent Length - Vertical; Flashing And Storm Collar Installation - Viessmann Vitocrossal 300 CU3A Installation Instructions Manual

Direct Venting (Two-pipe System)
Vent Length Requirements
Legend
a Equivalent length (exhaust)
b Equivalent length (air intake)
c min. 18 in. (457 mm) / max. 48 in. (1219 mm)
d min. 12 in. (305 mm)
e min. 12 in. (305 mm)
f 12 in. (305 mm) over max. local snow level
(check with your local weather office for details)
36
(continued)
Flue
Air
CU3A Venting Systems Installation

Maximum vent/air intake pipe length - vertical

Note: For combination of different vent/air intake pipe
diameters, such as Ø 4 in. stainless steel vent with
Ø 3 in. (PP(s), CVPC, PVC, ABS) air intake pipe,
the total equivalent length must be used for the
smaller pipe diameter.
Minimum vent length is 3.3 ft. (1 m).
IMPORTANT
All PP(s) vent termination elbows, must be secured in
place as specified by manufacturer.
IMPORTANT
For PP(s) systems, all exhaust vent and air intake piping
and elbows exposed outside, must be UV resistant
polypropylene (supplied by the vent manufacturer).
The total equivalent length specified for a two pipe system
is the total combined length of the exhaust vent and
air intake pipe system. Do not exceed these maximum
lengths. All PP(s) vent material and air intake (if PP(s)
used) must be ULC S636 listed.
Maximum equivalent length - vertical
Boiler model Intake Ø
CU3A 26, 35 3 in.
(80 mm)
CU3A 45, 57 3 in.
(80 mm)
A 7% boiler input reduction @ 60 m for all sizes and all
configurations.

Flashing and storm collar installation

Flashings and storm collars are field supplied.
Flashings and storm collars suitable for Type B vent
materials (or better) may be used.
To obtain flashings and storm collars, please contact
your local vent material supplier. Follow the installation
instructions supplied by the special venting manufacturer.
Follow local codes to properly isolate the exhaust vent
pipe when passing through floors, ceiling and roof.
Always check the marking on the pipe to make sure you
are using the correct material.
Exhaust Ø Equivalent
length
3 in. 198 ft.
(80 mm) (60 m)
4 in. 198 ft.
(110 mm) (60 m)