Mechanical (Kx) Thermostat Calibration - Vulcan-Hart ML-126743 Service Manual

VC4E & VC6E Series Full Size Electric Convection Ovens - SERVICE PROCEDURES AND ADJUSTMENTS
Fig. 37
a. Turn clockwise to increase,
counterclockwise to decrease
temperature
b. Repeat average temperature
calculation in Step 7.
NOTE: Allow oven to cycle at least two times between
adjustments before performing calculation.
a)
C. If above adjustment cannot be obtained,
replace 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.
F25105 Rev. B (0217)
If average temperature still
differs more than 10°F from
dial setting, adjust
thermostat calibration until
average temperature is
within tolerance.
6. Calculate the differential by subtracting the
temperature indicated when heat lamp goes out
from temperature indicated when heat lamp
comes on.
Differential - Heat lamp OFF - Heat lamp ON.
Example: 360° (lamp off) - 340° (lamp on) = 20°
A. The differential calculated should be less
than 30°F.
1)
2)
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.
[Temp. (lamp off) +Temp. (lamp on)] + 2 =
Average Temp. Example: 360° + 340° +2 = 350°
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)
2)
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If the differential is 30°F or less, the
thermostat is functioning properly. a.
Proceed to step 7.
a. Proceed to step 7.
If the differential is more than 30°F, the
thermostat is malfunctioning.
a. Install a replacement thermostat
and check calibration.
Remove the thermostat knob.
Hold the thermostat shaft and turn the
inner set screw clockwise to decrease
temperature or counterclockwise to
increase temperature (¼ turn = 35°F).