IDEAL Logic HEAT 12 Installation And Servicing page 54

70 aLTERNaTINg 'F' aND '2' - FLaME LOss
Does the boiler ignite for a short
time and then extinguish?
yES
Check the detection electrode and
associated harness for: continuity,
visual condition and position (Refer
to Frame 57). Check if condensate
pipe is blocked. Check if flue is
blocked.
Replace as necessary
Check siphon and condensate drain
pipe work for blockage and rectify if
necessary. Boiler now working OK?
NO
Replace Gas Valve
* note: due to the wave form of the rectified voltage, the reading will vary depending on the type of meter used to measure the
value. In general terms a reading greater than 150V indicates that the correct voltage is supplied to the gas valve.
71 aLTERNaTINg 'F' aND '3' - FaN FaULT
Does the wiring from the Fan to the PCB have secure connections at both ends
and has not deteriorated? Does the wiring have continuity?
Is there 230Vac at the Blue and Brown connections to the 3 way connection on
the Fan?
72 aLTERNaTINg 'F' aND '4' - FLOW ThERMIsTOR FaULT
Remove the Flow Thermistor from the CH Flow Pipe
and disconnect the wires.
Check the resistance using a suitable multimeter
connected across the thermistor's terminal pins.
At 25 o C expect
o
At 60 C expect
o
At 85 C expect
Is the Thermistor value correct?
73 aLTERNaTINg 'F' aND '5' - RETURN ThERMIsTOR FaULT
Remove the Return Thermistor from the CH Return
Pipe and disconnect the wires.
Check the resistance using a suitable multimeter
connected across the thermistor's terminal pins.
At 25 o C expect 9,700 - 10,300
o
At 60 C expect 2,400 - 2,600
At 85 o C expect 1,000 - 1,100
Is the Thermistor value correct?
54
Fault Finding
Is the Gas Pressure available at
NO
the Boiler Inlet (>18 mbar)?
Is 215Vdc supply available at the
Gas Valve while the flame is on?
(* See note)
Check spark generator and associated
harness for: continuity and visual
condition. (Refer to Frame 58) Are
these functioning correctly?
yES
Check ignition electrode and
associated harness for: continuity,
visual condition and position.
(Refer to Frame 56) Are these
functioning correctly?
yES
9,700 - 10,300 Ohms
2,400 - 2,600 Ohms
1,000 - 1,100 Ohms
Ohms
Ohms
Ohms
yES
yES
yES
NO
Fit a new Thermistor
yES
Is there continuity between the PCB and the Thermistor?
yES
Replace PCB
NO
Fit a new Thermistor
yES
Is there continuity between the PCB and the Thermistor?
yES
Replace PCB
Ideal Logic Heat -
NO
Check gas supply and
rectify fault
Check wiring from gas
NO
valve to PCB for continuity.
If the wiring is OK then
replace the PCB
NO
Replace Spark Generator
and Harness as necessary.
Replace Ignition
NO
Electrode and
associated harness as
necessary
NO
Rectify Wiring &
connections
NO
Replace PCB
yES
Replace Fan
NO
Check and replace wiring
as necessary
NO
Check and replace wiring
as necessary
Installation and Servicing