38 - EN
Maintenance
ERROR DESCRIPTION
SOLUTION
4
20
Bus power supply overload
A BUS power supply overload error may occur
due to the connection of three or more devices
within the installed system. Devices which may
overload the BUS network include:
- Multi-zone module
- Hybrid System or Heat Pump Energy Man-
ager.
- Solar pump assembly
- Instant domestic hot water production module
To avoid overloading the BUS power supply,
set microswitch 1 on one of the PCBs inside the
equipment connected to the system (except the
boiler and energy manager) to OFF.
1
ON
OFF
2
microswitch
7
01
Faulty Z1 delivery sensor
Check the connection of the relative probe.
Check the continuity of the probe.
Replace the probe if necessary.
7
02
Faulty Z2 delivery probe
7
11
Faulty Z1 return probe
7
12
Faulty Z2 return probe
7
22
Zone 2 overheating
Check whether the shunt is present and wheth-
er it is connected to terminal board ‘ST2’ of the
box, or check the maximum heating tempera-
ture adjustment for Zone 2 (parameter 525).
Check the connection of the safety thermostat
on terminal board ‘ST2’ of the box.
7
50
MZ hydraulic diagram not
defined
Set parameter 7.2.0. Hydraulic circuit diagram
7
53
Summary of Contents for MGM 2-ZONE HOT/COLD
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