SATK22
22
Electronic Circuit Board
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.
OTS
RT
PREPAID
AUX
RS-485 BUS
250Vac 3A
max
All the terminals are mounted on removable connectors to
facilitate wiring operations.
The following services are accessible:
•
External probe for outside compensated
temperature regulation
Use optional probe code 789833
OTS
RT
IN
IN
IN
O
•
External room thermostat
IMPORTANT! The connection is volt free. Do not
connect powered contacts.
RT
P
IN
IN
O
PREPAID
IN
O
AUX
????????
OUT
RS-485 BUS
•
Interface with pre-paid services
In case the HIU has to be interfaced with controllers
PREPAID 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.
Auxiliary contact
To implement the functions described on page 19 and
for the connection of the DHW recirculation pump
(see page 16)
IMPORTANT!
Max. voltage 230 V ac, max. current 3 A.
•
Mod-Bus
RS-485 port to connect HIU to a wired
network for Mod-Bus communication.
Connector colours
If the connectors of actuators and temperature probes are
disconnected during special maintenance work, comply with
the following instructions to reconnect them
:
Other electronic regulating functions
•
Reset modulating/mixing 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.
DHW probe:
Return probe:
Heating probe:
Heating valve actuator probe:
DHW valve actuator probe:
Safety thermostat:
