GB125 Concentric Vent - Buderus

Applications manual
GB125 Concentric Vent
Design Manual
3. Description of the systems
3.1. Scope
The concentric venting system described in this manual
is used exclusively for the Buderus GB125 boiler. No
other venting system can be used with this boiler, and the
venting system can not be used in conjunction with any
other boiler.
Do not replace or substitute any vent or combustion air
pipe with another brand, make, model, or material.
The Buderus GB125 is designed for balanced flue
operation only. All combustion air is drawn from the
outdoors. Use of balancers or barometric dampers defies
the system principle and is not permitted.
HTK - Direct vent through
side wall
(See page 12)
Part Number: 7747310386
DO - Vertical vent through
conditioned and unconditioned
space (NOT -suitable
for installation outdoors)
(See page 13)
Part Number: 7747200752
Installation and service of Buderus concentric venting
systems must be performed by a trained installer.
CAUTION! Never connect this concentric vent to
a common venting system
3.2. Available systems
GAK - Liner inside an existing
chimney;
Option 1: rigid pipe for a
straight chimney;
Option 2: flexible liner for
chimneys with an offset or
bend;
(See page 15)
Part Number: 7747200755
The three types of systems that are available are shown
in Fig. 1:
Observe the maximum vent lengths for each boiler size
as shown in Table 1.
Fig.1
Available systems
Systems are available as prepackaged kits that include
the essential components needed in every installation.
Refer to the descriptions of the individual system for
included items. For most systems extra straight pipe and
additional elbows must be purchased as needed. See list
of accessories for every system.
Max. length of flue pipe, feet (m)
Buderus flue pipe systems DN 80/125 Table 1
Boiler Size HT-K direct
vent
DO
vertical vent
GAK
chimney
liner
GB125 - 22 17' (5.2 m) 51' (17 m) 51' (17 m)
GB125 - 30 17' (5.2 m) 64' (21 m) 64' (21 m)
The GAK system draws combustion air from the
roof and may not be suitable for installation in
multi-flue chimneys, where a second flue vents a
combustion appliance that is used on a regular
basis. Flue gases could be drawn in with GB125
combustion air and cause system interruption.
GB125 - 35 17' (5.2 m) 71' (23 m) 71' (23 m)
The overall lengths include two elbows for the HT-K, and
one elbow for the DO and GAK kits. Every additional
elbow (accessory) reduces the maximum vent length by 3
ft (1 m).
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GB125 Concentric Vent Design Manual | 05.2009
Technical specifications are subject to change without prior notice