-15-
Revision 5/F3534
©
Moffat Ltd, April 2005
Turbofan Convection Oven
circulation fan will be turned Off. The control
panel Grill indicator will illuminate when the
thermostat is set to the Grill position and will cycle
On and Off with the main heating indicator light.
The E311 Turbofan convection oven features a
Roast-and-Hold system which can be used to
automatically set the oven to a fixed holding
temperature at the end of a timed cooking period.
From serial number 232054:
When the Roast-
and-Hold switch is turned On the switch will
illuminate and turn on a relay found on the inside
of the control panel. (This relay has two poles
with changeover contacts, but only one pole is
used). When this relay is switched On the
normally closed contact opens, isolating the
normal power supply to the oven thermostat and
the normally open contact closes supplying power
to the 3 hour roast timer.
To serial number 232053:
When the Roast-and-
Hold switch is turned On the switch will illuminate
and turn on a mini-contactor found on the inside
of the control panel. When this relay is switched
On a normally closed switch pole on the contactor
is open and the normal power supply to the oven
thermostat is isolated. A second normally open
switch pole is closed and this provides power to
the 3 hour roast timer.
If the roast timer is in the Hold (vertical) position
the timer switch contacts will be in their normally
closed position and supply power directly to the
Hold thermostat located behind the control panel.
The Hold thermostat is factory set to 75°C (167°
F) and will directly supply power to the bottom
heating element as required to maintain its preset
temperature.
If the main thermostat is turned On, power will
also be supplied to the top outer element coil
through the first switch contact of the thermostat
front switch assembly. In this case the
thermostat heating light will also cycle On/Off as
the Hold thermostat maintains temperature.
In the Roast-and Hold mode the 3 hour timer can
be set to a selected roasting time. During this
time period the normally open switch contacts of
the timer are closed. The timer has two change
over switches and in this position one is used to
supply power to its timing motor and the other is
used to switch power directly to the main oven
thermostat. During the 3 hour timer run-down
period the oven temperature will be controlled by
the main oven thermostat to the set temperature
and operate as previously described.
When the 3 hour timer has run down and reached
the Hold position the two switch contacts change
over to their normally closed position which
isolates power from the timer motor and the oven
thermostat. It also switches power back to the
oven hold thermostat. At this point the
temperature control is now maintained by the
hold thermostat as previously described. To
cancel the hold circuit the Roast-and-Hold switch
is turned Off. This turns off the contactor which
removes power from the 3 hour timer and closes
the contactor pole on the contactor that feeds the
main oven thermostat.
The factory preset hold thermostat can be
adjusted as required to change the holding
temperature if necessary. Refer Service section
for this procedure.
The following Troubleshooting Guide should be
used to identify any incorrect oven operation. On
correct identification of the operating fault the
Troubleshooting Guide will make reference to the
corrective action required, or refer to the Fault
Diagnosis section and/or Service section to assist
in correction of the fault.
