• Mod-Bus
RS-485 port to connect HIU to a wired network for
Mod-Bus communication.
Electronic circuit board
Other electronic regulator functions
• Reset diverter/modulating valve to zero
Immediately after the power supply has been switched on, the
position of the modulating valves is reset to zero.
• Pump anti-seizing
When the pump is not in use, it is powered on for a period of 5
seconds every 24 hours.
• Diverter/modulating valve anti-seizing cycle
The anti-seizing cycle for the diverter/modulating valve is run every 24
hours.
• Auxiliary contact
To implement the functions described on page 16 and for the
connection of the DHW recirculation pump (see page
13)
IMPORTANT! Max voltage 230 V ac, max current 3 A.
Optional connections
The electronic circuit board has a front door (shown in the adjacent
figure) that provides access to the connectors related to HIU optional
functions.
N.B. before working on the circuit board you must disconnect
the electric supply to the HIU.
The following services are accessible:
• External probe for outside compensated temperature
regulation
Use optional probe code 789833
• External room thermostat
IMPORTANT! The connection is volt free.
Do not connect powered contacts.
• Interface with pre-paid services
In case the HIU has to be interfaced with controllers
managing the heating and DHW production services by
means of “pre-paid” type logic.
The HIU interprets an open contact as “credit available”.
Closing the contact disables the heating and DHW
production services. When this condition occurs the user interface
display shows error “E80”.
IMPORTANT! The connection is volt free.
Do not connect powered contacts.
If the controller that manages the pre-paid service supplies a powered
contact, a relay must be interposed.
All the terminals are mounted on removable connectors to facilitate
wiring operations.
Connector colours
If the connectors of actuators and temperature probes are
disconnected during special maintenance work, comply with the
following instructions to reconnect them:
DHW probe:
Return probe:
Heating probe:
Heating valve actuator connector:
DHW valve actuator connector:
19
OTS
RT
PREPAID
AUX
RS-485 BUS
250Vac 3A
max
RS-485 BUS
?
OTS
RT
P
IN
IN
IN
OUT
I
RT
P
IN
IN
OUT
I
PREPAID
IN
OUT
I
AUX
R
????????
OUT
I
3
5
2
an die Art.Nr. 789835
• Gebruik deze enkel voor aansluiting op code 789835
• Utilice solamente para la conexión con cod. 789835
• Usare solo per collegamento a cod. 789835
• Use this wire for connection to code 789835 only
• À n'utiliser que pour la liaison avec code 789835
• Verwenden Sie dieses Gerät nur zum Anschluss
an die Art.Nr. 789835
• Gebruik deze enkel voor aansluiting op code 789835
• Utilice solamente para la conexión con cod. 789835
Pressure switch:
Safety thermostat:
