18
Externa 30 O
Cod. 3540T540 - 04/2009 (Rev. 00)
Flow diagram 2
Checking Central Heating Operation
Flow diagram 3
Checking the Fan/Flue Gas Circuit
Wait 2 minutes
Put CH temperature selector
to maximum
Ensure external controls
are calling for heat
Is LED4 flashing?
Does CH pump run?
YES
YES
Go to chart 3
Is relay RY101
switch on
Check and if
necessary replace
main board
NO
Is LED4 flashing?
Check and if is necessary
replace main board
YES
NO
Is relay RY100
switch on
NO
YES
Go to chart 3
NO
Check
limit thermostat
YES
Check pump
wiring
connection
NO
Check and if
necessary
replace pump
Does fan run?
Is relay RY100 switch ON?
NO
Go to charts 2
NO
Is 230V present across
fan terminals?
YES
Check air pressure
switch wiring connection in N.O.
NO
Check and if
necessary replace
air pressure switch
NO
Check and if
necessary replace fan
YES
Is air pressure switch
activated?
YES
NO
Check and if
necessary replace
air pressure switch
YES
Differential air pressure
across the air pressure
switch is greater than
180 Pascal?
Go to chart 5
YES
NO
Check and clean fan
Check flue and air
intake are correct
and clean
Check Venturi and
air pressure switch
tubes are clean
Check restrictor
is correct
