Maximum Vent Pipe Length - Vertical; Maximum Allowable Vent Length - Vertical - Viessmann Vitocrossal 300 CU3A Installation Instructions Manual

Single Pipe Venting (Room Air Dependent)
Vent Length Requirements

Maximum vent pipe length - vertical

All PP(s) vent material must be ULC S636 or UL 1738
listed. Size the exhaust vent pipe as specified in the table.
This table lists the maximum allowable vent length in feet
and meters of the exhaust piping. Vent diameter must not
be reduced at any point in the installation.
Maximum allowable equivalent length - vertical
Boiler Model
See note below
CU3A 26, 35 3 in. (80 mm)
CU3A 45, 57 4 in. (110 or 100 mm)
A 7% boiler input reduction @ 60 m for all sizes and all
configurations.
52
(continued)
System Ø Max. combined
equivalent vent
length (a+b)
198 ft. (60 m)
198 ft. (60 m)
CU3A Venting Systems Installation
IMPORTANT
For PP(s) systems, all exhaust vent piping and elbows
exposed outside, must be UV resistant polypropylene
(supplied by the vent manufacturer).
Legend
A Exhaust (straight coupling) with screen
B Flashings
C Support system
D Combustion air intake
E Combustion air opening (room)
a Equivalent length (exhaust)
b min. 18 in. (457 mm)
max. 48 in. (1219 mm)