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H50 SERIES GAS FRYERS
CHAPTER 1: SERVICE PROCEDURES
1-1
Inside the Ignition Module
TD
Out to
Gas Valve
To Alarm
25 V +
GND
HV
Ignition Wire Flame Sensor
Coil
1.1 Functional Description
H50 Series fryers contain a welded stainless steel frypot that is directly heated by a high efficiency
infrared burner system requiring approximately 43% less energy than conventional burners to cook
the same volume.
Self-contained combustion chambers (referred to as “burners”) are fitted into rails attached to the
sides of the frypot, one on each side. Each combustion chamber is fitted with special ceramic tiles
that are heated by the burning of a forced air/gas mixture. The tiles transfer their heat to the frypot
by means of infrared radiation, providing much more constant and uniform heat dispersion over the
surface of the frypot than do conventional burners. Because less heat is lost to the atmosphere in the
process, compared to “open-burner” designs, less fuel is required to achieve and maintain a given
frypot temperature.
In full vat units, gas flow to both of the burners is regulated by one electromechanical gas valve. In
dual vat units, each burner has its own valve. All fryers in this series are equipped with 24VAC gas
valve systems, and all are configured with electronic ignition.
THE ELECTRONIC IGNITION SYSTEM
An ignition module mounted in the component box or
“shield” (located behind the control panel) is connected to
an ignitor assembly at the burner. The ignition module
performs four important functions: it provides fuse
protection for the 24-volt circuit, provides an ignition
spark, supplies voltage to the gas valve, and proofs the
burner flame. The module contains a 4-second time delay
circuit and a coil that activates the gas valve. Three types
are in use. A closed-box design is used in most fryers, but
in some fryers built for export the module resembles an
interface board. A single dual-spark module is used on
current production full-vat fryers. Two single-spark
modules were used on full-vat fryers built before August
2000. All dual-vat fryers use two single-spark modules.
The ignitor assembly consists of a spark plug, an enrichment tube, and a flame sensor.
At start-up, the power switch is placed in the ON position, supplying approximately 12-volts DC to
the heat control circuitry in the controller or computer and to one side of the heat relay coils on the
interface board. If resistance in the temperature probe indicates the temperature in the frypot is
below 180ºF (82ºC), the current flows through a melt cycle circuit where a timer switch alternately
closes for 6 seconds and opens for 24 seconds. If the temperature is 180ºF (82ºC) or above, the
current flows through a heat circuit, bypassing the timer switch. In either case, ground is supplied
to