Fault Finding - Ferroli Sigma 30 FF 41-267-07 Installation And Servicing Instruction

8. FAULT FINDING

Before commencing any fault finding procedure on the boiler, ensure electricity is on to the appliance, the gas supply is
turned on, purged and is sound, and the system is full of water.
Note: in certain condition the fan and overheat thermostat may have 230 v at their terminals, but the fan will not run.
Intermittent problem may be due to the temperature sensor breaking down when under load although the resistance value
may be within the stated range.
Sticking gas valves may lead to boiler lock out problems. It is not possible to test for power to the gas valve due to the nature
of the plug on sequence board.
8.01 Boiler Operating Sequence
Permanent live to boiler
Switched live from controls read
Boiler thermostat calling
Temperature sensor calling
When all the above is present, the pump connection becomes live and the pump runs.
The grey wire of the control board on X5 becomes live, 230 v.
Air pressure switch has 230 v to the normally open (N.O.) contact.
Fan motor and overheat thermostat have 230 v al both terminals to earth.
If the air pressure switch is open circuit between its N.O. and common contact, the voltage at the overheat thermostat to
earth drops to almost zero. The white wire of the fan becomes a neutral and the fan runs.
The air pressure switch operates to make a circuit between its N.O. and common contacts.
If the overheat thermostat is closed circuit the ignition electrode will spark the gas, valve opens and the burner lights.
8.02 Troubleshooting - Quick reference guide
N.B.: To avoid incurring unnecessary expense, in the event of boiler shut down, check that this is not caused by a lack of
electricity, gas or low water pressure before calling the Customer Technical Service.
PROBLEM
Boiler lockout
Burner fails to ignite
No spark to the electrode
Sigma
CAUSE and REMEDY
After a number of attempts at ignition, the electronic unit always shuts down the
boiler
Check that the flue is clear and fitted correctly and that air has been vented from the
pipes - polarity is correct
Check that the electrode is positioned correctly and free
from corrosion deposits
No electricity
Wait for electricity to be restored
Blocked injector
Clean injector
Faulty flow temperature sensor
Replace flow temperature sensor
Faulty gas valve
Repair or replace gas valve
Fan not running
Check that electricity is reaching the fan
Faulty pressure switch or obstructed pipes
Replace the pressure switch or clear the pipes
During the ignition phase, there is no spark to the electrode
Check the boiler is connected to the mains and is efficiently earthed
27