Fault Finding; Blank Display; Burner Module Lockouts; No Ignition - IDEAL imax plus F80 Installation And Servicing

45 FAULT FINDING

SAFETY
Refer to Frame 42 for essential guidance on safety when
carrying out fault finding.
The preliminary electrical system checks are the FIRST
electrical checks to be carried out during a fault finding
procedure.
On completion of any service/fault finding task which has
required the breaking and remaking of electrical connections
the following checks MUST be repeated:
a Earth continuity
b Polarity
c Resistance to earth

BLANK DISPLAY

In the case of a blank display, check the following:
- Check the ribbon cable is correctly fitted to the display
board.
- Check that mains voltage is provided across terminals 19
and 20.
- If no power available, check external fuse.
- Check the ON/OFF switch is set to ON.
- Check the fuse '2AF' mounted on the MBD.
- Before replacing any blown fuses check for short circuits
on the 230V circuit, with particular attention given to the
wiring of external pumps or valves. Loads in excess of 1A
per external pump/valve will blow the fuse '2AF'.
- If power supply and fuses are OK, the MBD needs
changing.
WARNING. The external fuse and fuse '2AF' are part of the
230V circuit. Make sure the power is off before checking.
BOILER DOES NOT SATISFY CH REQUEST
- Check the connections of all external controls are correct.
- Check the condition of all wiring to external controls.
- Check the CH pump and its wiring.
- Check that the parameters are set correctly for the chosen
control method.
BOILER DOES NOT SATISFY DHW REQUEST
- Check the tank sensor/thermostat and its wiring.
- Check the 3-way valve/DHW pump and its wiring.
- Check that the parameters are set correctly.

BURNER MODULE LOCKOUTS

Note. To carry out checks on individual burner modules, it is
advised that all external controls are switched to 'OFF' so no
heat demand is placed on the boiler. Individual burners can
then be fired in TEST mode, see Frames 26 & 32.
When a burner module locks out, the corresponding red reset
button illuminates on the fascia.
Note. The blinking red LED on a CVI board indicates that it is
functioning correctly.
To reset the boiler, press and hold the illuminated red reset
buttons of each failed module and press the reset button on
the fascia.
Detail of electrical connections on the 'CVI' control boards mounted directly onto the gas valves.
WARNING!
To disconnect the
ignition lead from the
CVI hold directly on
the terminal (fast-on)
and not on the lead.
36
FAULT FINDING
The air pressure switch does not close:
In this situation the fan runs for 60 seconds, then goes into
lockout, illuminating the relevant push button on the fascia.
- Check the condition and connections of the silicon tubes to
the air pressure switch.
- Measure the signal across the air pressure switch. If
greater than 53 Pa replace the air pressure switch. If less
than 53 Pa check the following:
- Check for any blockages in the passage of air through
the boiler and then out through the flue.
- Check that the flue has been sized correctly and does
not create excessive resistance (>100 Pa).
- Check for dirt build up on the back of the burner skin
(see servicing section).
- Check operation of fan.
High limit thermostat is open:
In this situation the module goes into lockout, and after
approximately 30 seconds the relevant push button on the
fascia becomes illuminated.
If the module has overheated:
- Check for presence of water in the heat exchanger.
- Check for adequate water circulation through the section.
If the module has not overheated:
- Replace faulty overheat thermostat.
No flame is detected despite visible ignition through
sightglass:
- Check the connection to the ionisation electrode.
- Check for any distortion of the ionisation electrode, or
cracking of the ceramic.
- Check that the resistance between the probe and earth is
not zero.
- If all above OK, replace CVI board.

No ignition:

- Check for a visible spark on the ignition electrode through
the sightglass. If not visible, check condition of electrode
and wiring. If all OK replace CVI board.
- Check the gas valve opens correctly. Due to the nature of
the gas valve a burner pressure is difficult to measure.
Therefore it is advised that a manometer is connected to
the gas valve inlet pressure test point. When the gas valve
is energised a drop in pressure will be visible, if the valve
has opened correctly. If this is not the case, remove the CVI
board from the gas valve and measure the gas valve
solenoid resistance values. V1 should measure
approximately 2.9k Ω, V2 should measure approximately
1.4k Ω. If measured values differ significantly from these,
replace the valve. If values are OK replace CVI board.
- If ignition electrode and gas valve are functioning correctly,
check the condition of burner. Refer to service section on
how to clean burner, and replace if any signs of damage
are evident.
12 10
11
E. ACC.
E. RIV.
L
N
8 6 4
9 7 5 3
PV
PR
TL
E. ACC.Ignition electrode
E. RIV Ionisation electrode
LB
PR Rest button (on fascia panel)
LB Lockout warning light (within reset button)
TL High limit thermostat (local)
PV Fan air pressure switch
L - N Supply terminals on CVI
1-2 Ionisation signal to MBD
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Installation & Servicing
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