07/2009 - Art. Nr. 4200 1023 3700A
42
Troubleshooting
Eliminating defects
Causes and elimination of defects
When a failure occurs, check the prior
normal operation conditions:
1. Is the electrical supply available?
2. Is there any fuel oil?
3. Are all the regulating and safety
devices adjusted correctly - such as
the boiler thermostat, the protective
device against lack of water, the end-
of-stroke switches, etc.?
Fault
Cause
Corrective action
Nothing shown on display
Mains voltage off
Defective external fuse
Display-control unit connection broken
Defective display
MPA 22 defective
Check
Check / change
Check / reestablish the connection
Change
Change
“Safety chain” display
No reaction signal at terminal 7
Push in the bridging plug and/or check
the pressure switch / limiter
The burner will not start
Control unit-motor connection broken
Defective condenser
Defective motor
Incorrect control unit-servomotor
reaction signal
Reestablish the connection
Check / change
Check / change
Control unit / servomotors
Check / change
The motor runs for a short time only
Air pressure switch does not engage
Solenoid valve V1 does not open
No fuel oil
Check / change the setting
Check the compact ramp / change it
Inform the fuel oil supplier
The burner will not start
Defective compact ramp
Defective ignition transformer
Ignition electrodes position / ignition
cable Defective MPA 22 control unit
MZ 770S cell
Change
Change
Check / change
Check / change
Check / change
In case of a burner failure, a lighted
warning lamp will flash on the display.
The cause of the failure is also shown
and a failure code is emitted.