5
Trouble-shooting
18
Blue Seal Evolution Series GT45 / GT46 / GT60
©
Moffat Ltd, January 2007
Revision 1/
5.2
Fault Diagnosis
5.2.1
Pilot drops out
Figure 5.2.1b
Pilot flame too small
If pilot can be lit but the flame is too small to
impinge on the thermocouple, then check the gas
pressure. If ok, check the adjustment of pilot flow
by adjusting screw below control Knob on gas
control. If sufficient pilot flame cannot be
obtained, remove the pilot injector from the pilot
burner and check for blockages and correct size
injector.
Thermocouple faulty
(GT45 and GT60 Only)
Check thermocouple connections are firm and the
over-temperature lead connection to interrupter
block on the thermocouple is secure (loose
connections will cause resistance in millivolt
circuit and result in pilot outage).
If all connections are OK, then lights the pilots.
Hold in both control buttons and ignite flames,
wait 10 seconds then release the blue pilot
button only. If the pilot flames go out after
releasing the blue button then there is a problem
with the thermocouple circuit connected to the
flame failure valve.
If the pilot flames don't go out when the blue
pilot button is released then release the main
control button. If the pilot flames go out when
the main control is released then there is a
problem with the thermocouple circuit connected
to the main gas control.
To test the thermocouple connected to the flame
failure valve, disconnect the thermocouple from
the rear of the flame failure valve. Ignite the
pilots, and while still holding the flame failure
blue pilot button in measure the voltage between
the removed end of the thermocouple and earth.
The reading should be approximately 30mV. If
the reading is less than 10mV and there is
satisfactory flame impingement on the thermo-
Figure 5.2.1a
couple the thermocouple is faulty—replace.
If the voltage is over 10mV then there is a fault
with the flame failure valve electromagnet—
replace.
To test the thermocouple connected to the main
gas control, ignite the pilots and whilst holding in
the gas control button, measure the voltage
between the pilot burner side of the connector
block to earth. This should be approximately
30mV. If the reading is below 20mV and there is
satisfactory flame impingement on the thermo-
couple then the thermocouple is faulty—replace.
If the voltage is over 15mV refer to “Over-temp
tripped or faulty”.
Thermocouple faulty (GT46 only)
Check the thermocouple connection is firm and
the over-temp lead connection tot the interrupter
block on the thermocouple is secure. (Loose con-
nections will cause resistance in millivolt circuit
and result in pilot outage.
If all connections OK, then light the pilot, and
whilst holding the control knob in, measure the
voltage from the pilot side of the connecter block
to earth (e.g the body of the solenoid). This
should read approximately 30mV. If this reading
is less than 15mV refer to “Over-temp tripped or
faulty” section.
Pilot adjustment screw
Gas control
Flame failure
pilot button
Gas control
thermocouple
Pilot side of interrupter block
Earth
Figure 5.2.1c