H Open Flue Operation; Balanced Flue Operation; Lightning Protection - Viessmann vitodens Technical Manual

4.1 Flue gas systems

Balanced flue operation

Because of their sealed combustion
chamber, Vitodens gas fired condensing
boilers may be used for balanced flue
operation. They belong to the device type
C , C , C , C or C
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TRGI '86/96.
A common approval for Vitodens and
balanced flue systems applies to this type
of device.
In some Federal States, the leak test
(overpressure test) by the flue gas
inspector during commissioning as well
as the verification of the DIBt General
Building Approval, may be omitted for
these types of construction. Every
approved flue gas system can be used for
type C . The fuel gas system has not
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been tested with boilers.
The dimensions stated on pages 106 to
117 must be maintained.
The combustion air supply and the flue
gas are routed through one concentric
coaxial pipe (balanced flue system). The
combustion air is supplied through the
annular gap between the external
aluminium ventilation pipe and the flue
pipe.
Flue gases are exhausted through the
internal plastic pipe (PPs).
Open flue operation
4
Flue gas is routed through single wall
plastic pipes (PPs).
The flue gas system is approved with
certificates Z 7.2 1104 and Z 7.2 3028 (see
page 101).
The combustion air supply is safeguarded
via the annular gap between the flue pipe
and the ventilation air connection of the
flue outlet on Vitodens.
Flue gas high limit safety cut-out
According to approval certificates Z 7.2 1104
and Z 7.2 3028, the plastic flue pipe (PP
can be utilised up to flue gas
temperatures of120 ºC (type B).
Measures inside the device ensure that
the flue gas temperature of > 90 ºC will
not be exceeded.
Therefore, a high limit safety cut-out is
not required.

Lightning protection

If a lightning protection system is
installed, a metallic flue gas system
should be included in the lightning
protection scheme.
100
For flue gas and ventilation air systems
tested together with the gas fired wall
mounted boilers, some Federal States
(e.g. Northrhein Westphalia) waive the
according to requirement for a leak test (overpressure
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test) during commissioning by the flue
gas inspector.
We recommend that your heating
engineer carries out a simple leak test
during the initial start-up of your system.
For this it would be sufficient to check the
CO concentration in the combustion air
2
at the annular gap in the balanced flue
pipe. The flue pipe is deemed to be sound
if the CO concentration of the
2
combustion air is a maximum of 0.2 % or
the O concentration is a minimum of
2
20.6 %.
If higher CO
measured, check the flue gas system for
leaks.
In conjunction with the concentric dual
pipe (balanced flue system), the surface
temperature of Vitodens or the balanced
flue system will never exceed 85 ºC.
Therefore, clearances to other
components according to TRGI do not
need to be maintained.
(type B and B )
23 33
)
S
or lower O values are
2 2
For device types C and C the
63 43x
DIBt approved flue pipes from Viessmann
or alternative DIBt approved flue pipes of
other makes may also be used.
When using aluminium flue pipes, we
recommend the use of a condensate trap.
The balanced flue system is
DIBt-approved [Germany] with certificates
Z 7.2 1104 and Z 7.2 3028 (see page 101).
The boiler casing creates a system that is
sealed against its surroundings. Any leaks
caused by escaping flue gas are returned
via the combustion air, therefore
preventing flue gas from entering the
installation location.
When installing Vitodens in a basement
or on a lower floor, an existing chimney
or duct of sufficient size may be used for
routing the balanced flue pipe (type C
According to TRGI '86/96, flue pipes
which pass through several floors, must
be routed inside a duct with a fire
resistance rating of at least 90 minutes
and, for buildings of low height with at
least 30 minutes.
The flue gas/combustion air is routed in a
balanced flue pipe up to the chimney or
duct. The flue pipe is routed inside the
chimney or duct to above roof level.
Where no suitable duct is available, the
flue pipe may be routed to the roof
through a retro-fitted duct. This duct must
have Building Regulations approval and
provide fire resistance according to class
F 30 or F 90.
VITODENS
).
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