Installation guide

Direct Venting (Two-pipe System)
57
Vent Length Requirements (continued)
Maximum vent/air intake pipe length - horizontal (continued)
Legend
Support system
Exhaust pipe t ermination with screen
Combustion air intake with screen
a Equivalent vent length (exhaust)
b Equivalent vent length (air intake)
Maximum vent/air intake pipe length - vertical
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 lenghts. See
table 40., as well as fig. 49 and 50, for
reference.
Table 40. Maximum allowable equivalent length - vertical
Boiler Model
System Ø
See note
below
Max. combined
equivalent
vent length (a+b)
*2
HWB1B 10-26, 10-35 2” / 51mm
3” / 76mm
*1
4” / 102mm
*1
86ft. / 31m
164ft. / 50m
200ft. / 61m
HWB2B 9-19/26/35 2” / 51mm
3” / 76mm
4” / 102mm
115ft. / 35m
148ft. / 45m
180ft. / 55m
HWB2B 17-45, 17-60 3” / 76mm
4” / 102mm
98ft. / 30m
148ft. / 45m
HWB2B 30-80, 30-105 4” / 102mm 131ft. / 40m
*1
2” to 3” or 2” to 4 “ increaser field supplied. Do not order Viessmann 3” or 4” starter adaptor.
*2
See figure 49 and 50
5368 815 v2.0 b5368 815 v2.0 b
Vitodens
a
b
Starter Adaptor
Parallel Adaptor
Boiler Adaptor
Side Wall
Caulk here
(exterior caulking)
Air
Flue
Field Supplied
Exhaust/Air Intake
Pipe and Fittings
Fig. 50 Vitodens 200-W WB2B 17-45, 17-60, 30-80, 30-105