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6.0 SERVICE (Continued)
THERMOSTAT
The thermostat adjustment should not be changed. Check the following before changing the
thermostat.
1. With kettle cold, the pressure on the pressure gauge should read in the green vacuum zone
(25 to 30 inches Hg vacuum). If not, see ‘Re-establishing Vacuum” section.
2. The pressure switch may be set too high or too low and causing the out of adjustment
condition. A voltmeter should be used by a properly trained serviceman to determine if the
pressure switch or thermostat is actually cycling the burners. If the pressure switch is found
to be cycling the burners, see “Pressure Switch” section.
After verifying that the pressure switch is set and operating properly, the thermostat may be
adjusted using the set screw inside the stem. At maximum setting, the thermostat should cycle
off at a gauge pressure reading of 30 psi. Turn set screw clockwise to decrease pressure and
counterclockwise to increase pressure.
PRESSURE SWITCH
The pressure switch should not be adjusted until it is determined to be the cause of an operating
pressure difficulty. See “Thermostat” section to determine if the source of difficulty is the
pressure switch or thermostat.
The major difficulties caused by pressure switch mis-adjustment are:
1. Pressure relief valve opening, pressure rises above 45 psi.
2. Pressure in kettle is less than 30 psi and burner is being shut down by pressure switch (not
thermostat).
The pressure switch is preset for proper operation from the factory. It is adjusted to the
maximum pressure which will prevent the pressure relief valve from opening. During preheat to
the maximum thermostat setting (275EF), from either a cold condition or a lower temperature
setting, the temperature may overshoot the thermostat setting and be shut down by the
pressure switch. This is normal, however, after the kettle has cycled several times (empty) the
thermostat will begin cycling the unit.