37
3.4.2 - DHW CONTROLED BY
STORAGE TANK THERMOSTAT
The conditions mentioned at par. 3.4.1
above can be applied for this type of
operation as well, provided that the
DHW request results from the closing
of the hot water thermostat contact (con-
nected to terminals 7 - 8 of fig. 16 to its
sensor inside a proper storage tank
sheath).
In this case the parameter 1 value is to
be higher than or equal to the pre-set
DHW thermostat temperature. This is
necessary to ensure that the boiler be-
gins modulating at the correct flow tem-
perature.
Check all other parameters.
3.4.1 - DHW CONTROLED BY A NTC
SENSOR ON DHW STORAGE
TANK
The storage tank NTC sensor, availa-
ble at UNICAL’s, is connected to termi-
nals 7-8 (fig. 16). For the electrical con-
nection of the storage tank loading
pump or diverting valve see examples
in fig. 6.1 – 6.6 and wiring diagrams of
fig. 17.
Priority system wiring:
From the terminal-strip of fig. 16 it is
possible to use a 230 V signal to acti-
vate the storage tank loading pump
or the diverting valve. To connect a
motorised 3-way diverting valve, re-
fer to the wiring diagrams at par. 2.6.4.
It is advisable to use the activation
Parameter 1:
Storage tank hot water set temperature
Parameter 2:
DHW Production ON
Parameter b:
Flow temperature increase : the boiler water modulated
temperature is equal to parameter 1 + parameter b.
Parameter J:
Storage tank loading pump post-circulation (max. 270 sec)
Parameter L:
hysteresis between 5 and 14 °C.
The DHW mode operation is requested
when the storage tank water tempera-
ture goes under the pre-set DHW tem-
3.4 - DOMESTIC HOT
WATER (DHW) MODE
OPERATION
The boiler DHW mode operation is got
The following beside parameters are fundamental for the DHW mode operation.
3.3.3 - HEATING MODE OPERATION
BY OUTER COMPENSATOR (0
– 10 V signal)
By giving the 1
st
figure of the parameter
A the value 2 (e.g. A-2x) it means that
the request for more heat is driven by
an outer compensator.
When an outer compensator with 0 –10
V outlet signal is employed, this signal
can be combined with the boiler. By the
AM-4 PCB, the outer compensator can
be combined with the boiler. The con-
nection can be carried out on the termi-
nal-strip of fig. 16 (terminals 1-2).
The parameters applied are shown on
the right.
The boiler will switch off, if the flow
Parameter G:
the setting is carried out at a 0 V signal, equivalent to the mini
mum global flow temperature (parameter 4)
Parameter H:
the setting is carried out at a 10 V signal, equivalent to the mini-
mum outer temperature (parameter 3)
Parameter 6:
Temperature block upon heat request. According to the outer
temperature there will be no request for heat the if the calculat-
ed setting point for the flow temperature is lower than the para-
meter 6. This parameter can be used in summer: when the outer
temperature is high, a 25°C regulation can be calculated where
as the parameter 6 can be set to 30°C. In this case the request
for heat will be stopped, preventing the radiators from overheat
ing.
temperature exceeds by 5K the pre-
set flow temperature value (i.e. Pa-
rameter 3). The boiler will start again
as soon as the flow temperature has
gone under the pre-set value (Param-
eter 3) minus the heating system hys-
teresis (Parameter 8).
Note: outdoor sensor and 0 - 10V outer compensator cannot be connected simultaneously.
through the special AM-4 PCB, supplied
as standard in the panel board.
This PCB can work together with a nor-
mal thermostat or a NTC sensor con-
trolling the storage DHW tank and an
storage tank loading pump or a 3-way
valve.
The DHW mode operation takes priori-
ty on the heating system.
The terminals to be used are shown in
fig. 16. As for possible configurations see
fig. 17.
signal to supply the storage tank load-
ing pump through a relay. For its elec-
trical connections and programming,
refer to figs 6.1 – 6.2 – 6.4 - 6.8 and 17.
perature value (Parameter 1) plus the pre-
set hysteresis (Parameter L). The boiler
will begin modulating at the temperature
equal to Parameter 1 plus Parameter b.
The DHW mode operation will stop when
the storage tank water temperature ex-
ceeds by 5K the pre-set temperature of
Parameter 1.
