Chimney Connection; Flue Size; Connection To The Flue Gas Pipe - DeDietrich GT 430 Installation And Service Manual

4.6 Chimney connection

The high-performance features of modern boilers and their use in
specific conditions as a result of the advance in burner technology
(e.g. first-stage or low modulation range operation) lead to very low
flue gas temperatures (<160°C).
4.6.1

Flue size

Refer to applicable regulations while determining the size of the flue.
Please note that GT 430 boilers have pressurised and tight furnaces
and that the pressure at the connection to the chimney must not
exceed 0 mbar, unless special sealing precautions have been taken,
for instance in order to connect a static condenser/regenerator.
4.6.2

Connection to the flue gas pipe

The connection shall be removable, and offer minimum load losses,
i.e. it must be as short as possible with no sudden change in section.
Its diameter shall always be at least equal to that of the boiler outlet,
i.e.:
A: ø 250 mm: for 8 to 10 sections.
A: ø 300 mm: for 11 to 14 sections.
Fit a measuring point (Ø 10 mm hole) on the flue, in order to adjust
the burner (combustion check).
05/03/2013 - 300011893-001-02
For this reason:
- Use flue gas pipes designed to enable the flow of condensates
which may result from such operating modes in order to prevent
damage to the chimney.
- Install a draining tee at the bottom of the chimney.
The use of a draught moderator is recommended as well.
In order for the boiler to operate correctly, it is imperative
to respect the draught at the nozzle (= 0).
GT 430
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