Spheros thermo 231, Workshop Manual

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Thermo 230 / 231 / 300 / 301 / 350 5 Troubleshooting
505
5.3.2.2 Fault Symptom "Flame-out"
NOTE
Heaters with control unit 1572D:
If the heater performs 5 consecutive attempts to start due
to a malfunction, the heater enters an error lockout and
stops any further attempts to start. This error lockout is
superior to the normal error lockout condition.
The error lockout reset is achieved by switching the heater
on and disconnection of the heater power supply during
run-down.
5.3.2.3 Fault Symptom "Low Voltage"
Switch on heater.
Is combustion air fan
operating? Electrical power
supply,
fuses, plug contacts,
relays o.k.?
(control unit 1572
only) Replace defective
electrical
components.
Is fuel filter contaminated
or jellied? Is fan wheel free to
move? Check cap, motor and
fan wheel.
Is motor o.k.?
Is viewing glass of
flame sensor
contaminated?
Clean window and
viewing glass.
Replace nozzle.
YES
NO
Is fuel free of bubbles
in supply and return?
Replace filter and check fuel low
temperature rating.
Is nozzle free of
foreign matter and
deposits?
Control unit defective,
replace.
Replace motor.
Thermo 231/301
No fuel supply. Is solenoid valve o.k.?
(5.3.2.7)
Is voltage present on plug contact A3? Is electrical wiring
o.k.? Make electrical
connections.
Replace power supply
line.
YES
NO
Disconnect heater from battery supply.
Is battery properly charged?
Connect heater.
Is voltage between plug contacts A3 and A6
approx. 0.5 volts less than on battery?
Control unit defective, replace.
Is electrical power supply line
to heater o.k.?
Control unit defective,
replace.