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STEMkW Special ed 01/08 EOLO Mini kW Special
Technical DocumentationTechnical Documentation
D.h.w. request.
When domestic water is drawn it causes the contact of the
d.h.w. ow switch (S4) to close and enables operation in the
d.h.w. mode.
Burner ignition follows in exactly the same way as it does for
the central heating phase.
During the rst few seconds after the gas valve (Y1) has been
powered, the current to the modulating coil (Y2) is limited to
the predened soft ignition current.
When the ame is detected, the signal to the modulating coil
increases so as to immediately reach (if requested) the maximum
power set on the gas valve.
Flame modulation then occurs with reference to the die-
rence between the ow temperature coupled to the d.h.w.
temperature setting and the temperature measured by the
ow probe (B1).
When the reference temperature is reached, the burner is
kept working at minimum power and switched o when the
limit temperature of 85°C is reached (factory set with a xed
set-point).
By way of the “D.h.w. thermostat” parameter it is possible to
establish that when the set value (+8 °C) is exceeded the contact
of the K1 relay opens, reclosing as soon as the temperature
drops (+6.5 °C) (correlated d.h.w. set -point).
Antifreeze request.
When the temperature measured by the heating ow probe
(B1) drops below 4°C, the P.C.B. 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).
e anti-freeze function is not enabled if the boiler main switch
is on (Stand-by).
“Chimneysweep” request.
By turning the main switch (R10) round to Reset for 8 to 15
seconds, upon its release the P.C.B. enables boiler ignition
and keeps it working at the maximum central heating power
set for 15 minutes.
During this time only the limit thermostat function is observed
(90°C) which is carried out by means of the central heating
ow probe (B1).
e function is indicated by the simultaneous ashing of
LEDs (2) and (3) and by the code “E07” on the CAR display
(if installed), it cannot be started if there is an ongoing d.h.w.
request.
It can be interrupted by cutting power to the circuit, putting
the main switch on (Stand-by) or after the 15 minutes.
* see Integrated P.C.B. programming.
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