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FULL SIZE ELECTRIC CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
F25105 (December 2001) Page 18 of 60
Differential Heat lamp OFF Heat lamp ON
Example
: 360 (
lamp off
) 340 (
lamp on
) 20
[
Temp
.(
lamp off
)
Temp
.(
lamp on
)] ÷ 2
Average Temp
.
Example
: 360 340 ÷ 2 350
d. Rotate the knob to the lowest
temperature setting then back to
350°F.
e. Repeat the average temperature
calculation in step 7.
NOTE:
Allow the oven to cycle
at least two times between
adjustments before performing
the calculation.
a) If the average temperature
still differs more
than 10 °F
from the dial setting, adjust
the thermostat calibration
until the average
temperature is within
tolerance.
C. If the above adjustment cannot be
obtained:
1) Turn the power switch OFF.
WARNING:
DISCONNECT THE ELECTRICAL
POWER TO THE MACHINE AT THE MAIN
CIRCUIT BOX. PLACE A TAG ON THE CIRCUIT
BOX INDICATING THE CIRCUIT IS BEING
SERVICED.
2) Replace the temperature control and
check calibration.
MECHANICAL (KX)
THERMOSTAT CALIBRATION
1. Place a thermocouple in the geometric center
of the oven cavity.
2. Set the power switch to ON.
3. Set the thermostat dial to 350 °F.
4. Allow the oven temperature to stabilize
(normally 3 cycles).
5. Record the temperature when the thermostat
cycles OFF and ON for at least three complete
cycles.
6. Calculate the differential by subtracting the
temperature indicated when heat lamp goes out
from temperature indicated when heat lamp
comes on.
A. The differential calculated should be less
than 30 F.
1) If the differential is 30 °F or less
, the
thermostat is functioning properly.
a. Proceed to step 7.
2) If the differential is more
than 30 F,
the thermostat is malfunctioning.
a. Install a replacement thermostat
and check calibration.
7. Calculate the average temperature by adding
the temperature indicated when the heat lamp
goes out to the temperature indicated when the
heat lamp comes on and dividing this answer
by 2.
A. If the average temperature is 15 F or less
from the dial setting, the thermostat is
properly calibrated.
B. If the average temperature is more
than
15 F of the dial setting, the thermostat
calibration must
be adjusted.
1) Remove the thermostat knob.
2) Hold the thermostat shaft and turn the
inner set screw clockwise
to decrease
temperature or counterclockwise
to
increase temperature (¼ turn =
35 F).
8. Replace the knob and verify the setting is still
at 350°F.
9. Repeat step 7 until the average temperature is
within tolerance.
NOTE:
Allow the oven to cycle at least two times
between adjustments before performing the
calculation.