Chapter 1: Service Procedures; Functional Description; The Electronic Ignition System - Frymaster OCF30 Service & Parts Manual

CHAPTER 1: SERVICE PROCEDURES

1.1

Functional Description

OCF30™ series gas 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 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. All fryers in
this series are equipped with 24 VAC gas valve systems, and all are configured with electronic ignition.
1.2

The Electronic Ignition System

An ignition module mounted below the component box (located behind the control panel) is connected to an
ignitor assembly at the burner. The ignition module performs five important functions: it provides fuse
protection for the 24-volt circuit, provides an ignition spark, supplies voltage to the gas valve, provides the
alarm circuit (24V) to the controller and proofs the burner flame. The module contains a four 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
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 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 six 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
the other leg of the heat relay coils, which closes electronic
switches in the 24 VAC circuit to provide current to the ignition
module. Circuitry in the ignition module sends 24 VAC to the gas
valve via a normally closed high-limit switch and a normally
closed drain safety switch. Simultaneously, the module causes the
ignitor to spark for four seconds to light the burner. A flame
sensor verifies the burner ignition by measuring the flow of
microamps through the flame. If the burner does not light (or is extinguished), current to the ignition module
is cut, the gas valve closes, and the ignition module "locks out" until the power switch is turned off and then
back on. A probe monitors the temperature in the frypot. When the programmed setpoint temperature is
reached, resistance in the probe causes the heat cycle circuitry in the controller to cut off current flow through
the heat relay. This in turn cuts off the 24 VAC to the ignition module, causing the gas valve to close.
OCF30™ SERIES GAS FRYER
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