25
Fault and Control Programme Indication
The position of the cam can be read through the
sight glass on the control box. This indicates the
position in the programme run and the type of fault.
No start because control loop is interrupted.
||||
Specified time for air pressure signal.
P
Fault condition due to absence of air
pressure signal.
Pre-purge
1.
Fault condition because no flame signal is
available.
2.
Release of 2nd stage gas valve. (If
applicable)
Partial or full load operation.
Trouble-Shooting
Burner will not start, control programme indicator
does not rotate.
1.
Check that external wiring is correct.
2.
Check for electric supply on terminal 12, which
will also determine if the control thermostats are
calling for heat. Check that the incoming neutral
conductor is wired into terminal 8.
3.
Press reset button to ensure that the box is not
in lockout.
Burner will not start, control programme indicator
rotates continuously.
1.
Check wiring to air proving switch across
terminals 3, 6 & 11.
2.
Check air proving switch.
Burner motor runs for 5 seconds and then control
box locks out indicating the symbol
P.
1.
Check air proving switch setting and burner air
setting.
2.
Check wiring to air proving switch.
3.
Check air proving switch.
4.
Check for adequate air supply to the appliance.
5.
Check for blockage in chimney.
Burner motor starts and goes to lockout at the end
of pre-purge. Symbol
1.
indicated.
1.
Check that gas supply is on.
2.
Check that ignition is present after end of pre-
purge period.
TROUBLE SHOOTING GUIDE
3.
Check that the start gas valve is energised and
is opening during safety time.
4.
If necessary change control box.
Burner starts, flame established, control box locks
out displaying symbol
1.
1.
Check polarity of wiring for live and neutral to
control box base. Live to terminal 12, neutral to
terminal 2.
2.
Check that flame detection probe is correctly
positioned in the flame. Ensure that the probe
insulation is sound, free from cracks or
moisture. Check that probe is not in contact with
other metallic parts of the burner.
3.
Check that burner is effectively earthed and
bonded to the incoming earth wire from the
mains supply.
4.
Check for interference to the flame signal from
the ignition spark. This can be determined by
the flame signal current with a D.C.
microammeter. Correct polarity of the meter
connections must be observed, with the positive
side of the meter connected into terminal 1. If
the flame is established and the meter tends to
move in a reverse direction, this can be an
indication that
the
ignition is
causing
interference to the flame signal. It may also be
an indication that there is insufficient earth
contact with the flame.
5.
Change the control box if necessary.
Causes of lockout can be :
1.
Inadequate air supply to air proving switch,
switch wired incorrectly.
2.
No ignition, ignition electrode incorrectly
positioned or cracked insulator.
3.
Flame probe incorrectly positioned, cracked
insulation, flame probe in contact with earth
moisture present on probe affecting insulation.
4.
Live and neutral connections reversed.
(Reversed polarity)
5.
Inadequate earth contact with flame signal.
6.
Gas valves not properly closed in shut down
position.
7.
Faulty control box.
