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Technical Documentation
Technical Documentation
D.h.w. request.
When some domestic hot water is drawn it causes the contact
of the d.h.w. flow switch (S4) to close and enables operation
in the d.h.w. mode.
Burner ignition then occurs as it does for the central heating
phase.
During the first few seconds after the gas valve (Y1) has been
powered, the current to the modulating coil (Y2) is limited to
the predefined soft ignition current.
Once the flame is detected, the signal to the modulating coil
is increased so as to immediately reach maximum power set
on the gas valve (if requested).
Flame modulation then occurs with reference to the differ-
ence between the delivery temperature chosen as the d.h.w.
temperature setting and the temperature measured with the
delivery probe (B1).
When the reference temperature is reached, the burner is
kept working at minimum power and switched off when the
limit temperature of 85°C is reached (factory set with fixed
set-point).
By way of parameter P3 "D.h.w. set-point" it is possible to
make the burner switch off (opening of the K2 relay contact) at
the set temperature (correlated set-point).
Antifreeze request.
When the temperature measured by the central heating delivery
probe (B1) drops below 4°C, the board enables ignition and
keeps the boiler working with the burner at minimum central
heating power until a boiler temperature of 42 °C is reached
(radiator antifreeze).
"Chimneysweep" request.
Pressing the "Reset" push button (S3) for at least 10 seconds
and releasing it, the board enables boiler ignition and keeps
it working at maximum central heating power set for 15
minutes.
During this time only the limit thermostat function is ob-
served (90°C) which is carried out by means of the delivery
probe (B1).
The function is indicated on the boiler display panel by the
flashing of the (
and
), symbols; it cannot work if there
is an ongoing d.h.w. request.
It can be interrupted by cutting power to the circuit, putting
the boiler on
(Stand-by), or by either carrying out a d.h.w.
request or after the 15 minutes.
STNM ed 07/07
NIKE Mini Export
27
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