Mechanical Thermostat Calibration (Vc4Gs/6Gs) - Vulcan-Hart VC4G Service Manual

VC4G & VC6G SERIES FULL SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
a)
C. If the above adjustment cannot be obtained,
replace the temperature control and check
calibration.
UNITS AFTER JUNE 2013
1. Place a thermocouple in the geometric center of
the oven cavity.
2. Set the ON-OFF-COOL DOWN switch to ON.
3. Set the NORMAL - GENTLE BAKE switch to
NORMAL.
4. Set the temperature control dial to 350°F.
5. Allow the oven temperature to stabilize (normally
3 cycles).
6. Record the temperature at which the Heat lamp
goes OFF and comes ON for at least two
complete heating cycles.
7. Calculate the differential by subtracting the
temperature indicated when the lamp goes out
from the temperature indicated when the 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 20°F.
1) If the differential is less than 20°F, the
temperature control circuit is
functioning properly.
a. Proceed to STEP 8.
2) If the differential is more than 20°F:
a. Check the temperature probe as
outlined under TEMPERATURE
PROBE TEST.
b. If the probe is functioning properly
then temperature control is
malfunctioning.
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.
Install a replacement
temperature control and
check calibration.
8. Calculate the average temperature by adding the
temperature indicated when the lamp goes out to
the temperature indicated when the 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 less than 10°F
from the dial setting, the thermostat is
properly calibrated.
B. If the average temperature is more than
10°F from the dial setting, the thermostat
calibration must be adjusted.
1)
2)
NOTE: Allow the oven to cycle at least two times
between adjustments before performing the
calculation.
C. If the above adjustment cannot be obtained,
replace the temperature control and check
calibration.
MECHANICAL THERMOSTAT
CALIBRATION (VC4GS/6GS)
1. Place a thermocouple in the geometric center of
the oven cavity.
2. Set the ON-OFF-COOL DOWN 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.
Page 25 of 75
Loosen the temperature control knob
set screw and remove the knob from
the stem.
Access the adjustment potentiometer
located at the 3 o'clock position.
a. Turn clockwise to increase,
counterclockwise to decrease
temperature
b. Repeat the average temperature
calculation in STEP 8.
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.
F24682 Rev. D (1016)