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43
AST 14 C 255/00
CTFS Configuration (forced draught)
The type of boiler (sealed chamber or open chamber) is automatically recognised each
time the board is supplied with power. The board attempts to read the inlets dedicated to
the air pressure switch. During such phase, “CHA” will appear on the boiler display and
upon the following recognition (which must take place within the first two minutes) C
(sealed chamber) will be displayed for 5 seconds.
No request will be performed during boiler type recognition.
In case of wrong self-recognition, see the specific paragraph on page 82.
Boiler hydraulic configuration (with P3=3)
For heating-only boilers to which a DHW system is combined, the board is able to manage
different hydraulic configurations through parameter P28 (default setting is 0) depending
on system type.
The two configurations allowed are listed below:
P28=0, boiler pump + deviating valve: DHW system is managed by the operation of
both the boiler pump and of the three-way deviating valve. The latter should be of
spring return type and is to be connected to terminals 24 and 25 of the boiler.
Warning: respect the priority toward the DHW system when installing the valve
(valve normally open to the domestic hot water heating circuit).
P28=1, double pump: the DHW system is managed by a dedicated external pump
to be connected to the terminals 24 and 25.
Boiler pump is off during domestic hot water heating.
Reference wiring diagrams are given below:
sc
h
eda
MVD
HEATING
D.H.W.
PR
sc
h
eda
PR
PS
PR
: boiler pump
MVD
: three-way deviating valve
PS
: DHW pump
