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17
AST 14 C 259/00
3.4 BI-THERMAL HEAT EXCHANGER
Bi-thermal heat exchanger allows
reducing consumption as well as waiting
times during domestic hot water production,
without any need of a plate heat exchanger
.
It consists of two (inner and outer) copper
circuits. The first one, oval-shaped, is to be
used by the CH system only; while the
second one, diamond-shaped, is dedicated
to the DHW circuit. This shape (see picture
below) has been especially designed to
eliminate any limestone deposit and noise problems.
To this end, only three of the four contact points of the inner pipe are welded to the circuit,
while the other one is left "free". Metal parts movement thus prevents limestone from
depositing and obstructing ducts, by reducing at the same time any noise originated by
thermal expansion.
In addition, heat exchanger outer finning allows a uniform temperature all over the surface.
Circulation pump is enabled only during CH operation, while it is stopped during DHW
operation in order to ensure a greater heat exchange to the inner circuit. This is the reason
why, we talk about still water (AF) boiler.
The connections between heat exchanger and pipes are ensured by special clips, as the
system is hydraulically sealed with OR seals on pipes.
WARNING: to replace heat exchanger, proceed as follows:
- remove combustion chamber front panel;
- remove expansion vessel;
- remove flue fan and hood;
- release sealing clips;
- remove exchanger working from above, and replace it;
- refit all removed parts, making sure to duly lubricate OR seals.
Bi-thermal heat
exchanger section: