Vent Length Requirements; Maximum Vent Length; Standard Sizes Of Boiler Flue Gas Adaptors; Equivalent Vent Length Calculation Example - Viessmann Vitodens 100-W WB1B Series Installation Instructions Manual

Rigid Venting Systems Installation Instructions

Vent Length Requirements

Maximum vent length

Table 5. Standard sizes of boiler flue gas adaptors
Boiler model
WB1B 26, WB1B 35
WB2B 19, WB2B 26, WB2B 35
WB2B 45, WB2B 60
WB2B 80, WB2B 105
WB2B 80
WB2B 105
Table 6.
Boiler model
WB1B 26, WB1B 35
WB2B 19, WB2B 26
WB2B 35
WB2B 45, WB2B 60
WB2B 80, WB2B 105
* 1
If used with increasers 60/100 to 80/125.
*
2
If used with increasers 60/100 to 100/150.
* 3
If used with increasers 80/125 to 100/150.
Fig. 13 Equivalent vent length calculation
Legend
A 87º elbow
B Vent pipe 3.3 ft. (1 m)
C Vent pipe 1.6 ft. (0.5 m)
D Vent termination
* 4
First elbow not included in equivalent vent calculation.
For maximum equivalent vent length on all models see
g
tables 6 and 7, and Figs. 13 and 14.
Do not exceed the maximum vent length.
g
First 87º elbow on boiler is not included in equivalent
g
vent length calculation.
60/100
82 ft. (25 m) (see Fig. 13)
33 ft. (10 m)
26 ft. (8 m)
Side Wall Vent Installation (Coaxial)
Vent system
80/125
98 ft. (30 m) * (see Fig. 14)
1
43 ft. (13 m)* 1
36 ft. (11 m)*
1
33 ft. (10 m)
Table 7.
Type of fitting
87º elbow/
87º inspection tee
45º elbow

Equivalent vent length calculation example

2 x 87º elbow.......................................3.2 ft. (1 m)
2 x vent pipe (1 m)................................6.6 ft. (2 m)
1 x vent pipe (0.5 m).............................1.6 ft. (0.5 m)
1 x vent termination..............................2.4 ft. (0.73 m)
Total equivalent length.........................13.8 ft. (4.23 m)
IMPORTANT
First elbow not included in equivalent vent calculation.
Always include vent termination length in calculations.
Adaptor size
60/100
60/100
80/125
110/150 M&G
110/160
InnoFlue
100/150 or 110/160
118 ft. (36 m) * (see Fig. 14)
2
52 ft. (16 m)* 2
49 ft. (15 m) *
43 ft. (13 m)* 3
43 ft. (13 m)
Equivalent length
1.6 ft. (0.5 m)
1 ft. (0.3 m)
2
21