Alfa Laval Micro - 14 Troubleshooting the CM721

Alfa Laval Micro
Installation, service and operating instruction
44
14 Troubleshooting the CM721
Symptom
Remedy
Blank Display
No power to the thermostat.
Check batteries are installed by
removing the battery cover.
Check batteries have been installed in
the correct orientation.
Replace the batteries.
Display shows flashing
symbol
The batteries in the thermostat
are low on power.
Replace the batteries.
Display shows
symbol.
A fault has occurred in your
heating system.
Remove and re-insert the batteries.
If the symbol does not clear
after a few minutes contact Alfa Laval.
Display shows the
word 'SERVICE'
The installer has set a scheduled
maintenance alert period on your
CM721 as a recommendation
that your heating system should
receive a routine inspection.
Call your installer to arrange a
maintenance visit.
Note: The CM721 and heating system
will continue to operate as normal.
Relay Box (BDR91)
red LED is constantly
on or flashing
The relay box receives no RF
messages from the room
thermostat:
RF signal is blocked due to
wrong location of the room
thermostat.
Room thermostat batteries are
exhausted.
Re-locate the room thermostat following
instructions in section 6 Installing the
CM721 wireless system.
Replace batteries in the room
thermostat.
NOTE: The boiler can be controlled
manually when the RF communication
is lost: Press the BDR91 push button to
switch the boiler on and off. When the
green LED is on – the boiler is on.
The room thermostat
displays the symbol
but the relay box relay
does not switch on
This is normal operation. The
relay box cycles the relay on and
off for times proportional to the
demand signal (0-100%) from the
room thermostat. The symbol
only indicates that the demand
value is greater than 0%.
Using the button change the
temperature set point by a few degrees.
The relay box should switch the relay on
after a few seconds delay.
The relay box does not
react to set point
changes on the room
thermostat.
The room thermostat and relay
box are not bound.
Reset the relay box by pressing and
holding the push button for 15 seconds.
Then follow the binding / rebinding
procedure as described in chapter 7
Binding/rebinding the CM721.
After the binding
procedure the red LED
is on and the green
one is flashing once
every 3 sec on the
relay box
Incorrect or incomplete binding
procedure.
Incorrect position of the room
thermostat during binding.
Repeat the binding procedure.
Repeat the binding procedure keeping
approx. 1 m distance between the relay
box and the room thermostat.