Zehnder EASY 5.0
24
14.2. Checks prior to any diagnosis
Before undertaking any diagnosis procedure, the technician must:
■
check the network and its compatibility with the unit, in particular:
Actual layout: does the nominal operating point of the system (unit + network) enable the unit to operate correctly?
Examples: MAC2/QUATTRO: duct network diameter too small, LOBBY: duct network too short, etc.)
Type of fan controller (speed, pressure or volume): is the type of fan controller in the unit consistent with the type of
network?
Do the control devices (zone registers) installed in the network have the correct dynamics and minimum/maximum
opening positions for the unit?
■
Check for active alarms (active alarms menu) which indicate that there is currently a problem and point to possible
causes
■
Check the alarm history (alarm history menu) which shows the last 100 recorded alarms. The time and date the alarms
occur is important because you can check if the problems happen on a regular basis (e.g. every day at the same time),
or if they correspond to particular times that could correspond to the setting of the time schedules (reduced operation,
normal operation, night cooling, etc.), which could imply a wrong setting in this respect.
■
Check the power supply to the controller (24V AC) or the lighting of the green P/B LED on the faceplate of the
controller
■
Check that there are no external forced operation setpoints (low-speed remote order, high-speed remote order, stop
order)
Check the status of the digital inputs (DI) and the wiring
■
Check that there are no external setpoints from the communication (ports P1 or TCP-IP). To do this, the technician
must:
Check the physical presence of the wiring on the corresponding ports and disconnect if necessary
The flashing green LEDs P1RxTx and TCP/IP on the controller faceplate indicate that there is communication between
the controller and an external device (BMS/CTM). Communication takes precedence over external setpoints (DI),
which in turn take precedence over internal setpoints (time programming).
The presence of a particular operating mode forced by the BMS/CTM is visible from the “BMS request” status on
home page 3 (see XXXV.5.c Home page 3).
■
Check that there is no function in manual mode
■
Check the machine settings:
time schedules (night cooling, reduced operation, normal operation, shutdown period)
Fan setpoints
Temperature setpoints
■
Check the condition of the filters and replace if necessary
■
Check that the electrical terminals and plugs are properly tightened.
14.3. Simplified diagnosis
As a first step, it is necessary to distinguish between a blocking fault (the machine is stopped and does not work) and a
non-blocking fault (e.g. the machine works but stops/starts sporadically).
A blocking fault is characterised by the permanent presence of an active Class A alarm with “normal stop” action. For
this type of alarm (e.g. electric heating coil overheating), as long as the cause has not disappeared and the alarm has
not been manually acknowledged, the unit will not restart. It will also be necessary to physically reset the thermostat
itself.
A non-blocking fault is characterised by the absence of an alarm (external fault in the machine), or by the presence of a
class C alarm (warning).
The alarms and faults table (see XV.10 Alarms and faults table) summarises all possible alarms and faults and the causes
and remedies that allow the diagnosis and checks to be made for each of them.
14.4. Advanced diagnosis
If the above steps have been carried out and the fault is still present, an advanced diagnosis is necessary. To do this, it is
necessary to know the machine's control loops and the input/output information required for each of them.
Z-MASTER-V1122-CSY-INM-Zehnder Easy5.0
