Buderus Logano GE315 Technical Manual page 8

2 Technical description
Hot gas routing
The Ecostream cast iron boilers Logano GE315, GE515
and GE615 are designed according to the 3-pass
principle with a burnout combustion chamber. The
geometry of the cast iron boiler sections results in precise
routing of the hot gas flow for optimum heat transfer. The
hot gases leave the combustion chamber by the back
boiler section, where they are re-routed to the front. They
then flow through the secondary heating surfaces of the
second hot gas flue. After being reversed again between
the front section and front door of the boiler, the gases
flow over the secondary heating surfaces of the third hot
gas flue to the flue outlet at the back of the boiler
( Fig. 5). The oil or gas flame, especially with cleaner
burning pressure-jet oil and gas burners, can burn out
unhindered.
1
2
3
Fig. 5 Hot gas routing in the Logano GE515
1 Combustion chamber (first hot gas flue)
2 Secondary heating surfaces of the second hot gas flue
3 Secondary heating surfaces of the third hot gas flue
The 3-pass principle and the water-cooled combustion
chamber with direct heating surfaces offer ideal
conditions for low emissions. This is especially true in
conjunction with the advanced pressure-jet oil and gas
burners, which are matched to the boilers.
The secondary heating surfaces are arranged
symmetrically around the combustion chamber. Some of
them have hot gas baffle plates, which optimise the speed
of the hot gas flow. This creates more intensive heat
transfer to the boiler water. The result is a high standard
seasonal efficiency [to DIN] and low flue gas
temperatures.
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If the flue system is not suitable for such low flue gas
temperatures, individual hot gas baffle plates or
turbulators can be removed from the secondary heating
surfaces. In this case, the flue gas temperatures would be
approx. 20 °C to 30 °C higher.
6 720 644 097-04.1il
6 720 646 864 (12/2010) – Technical guide Logano GE315, GE515 and GE615