1-2
1.1 Functional Description (cont.)
An electromechanical millivolt gas valve regulates gas flow to the burner manifold. Frymaster Dean
millivolt fryers use a pilot ignition system to control burner firing.
Operating
Thermostat
Thermopile
Pilot
High-Limit
Main Valve Magnet
Pilot Magnet
Gas Valve
Pilot Ignition System
The pilot ignition system is made up of the pilot orifice, pilot hood, and a thermopile or
thermocouple. The pilot serves two purposes: lighting the burner and heating the thermopile/
thermocouple. In operation, the thermopile/thermocouple is in contact with the pilot flame and
generates millivolts. The millivolt output passes through a normally closed high-limit switch and
energizes the gas valve pilot coil, which in turn opens the pilot valve. If the pilot flame is
extinguished, voltage is lost to the gas valve pilot coil and the pilot valve closes.
Thermostats
Frymaster Dean millivolt fryers are equipped with adjustable operating thermostats. The
temperature at which the thermostat opens and closes is adjusted by turning a knob.
Frymaster Dean millivolt fryers are also equipped with a high-limit thermostat. In the event that the
fryer fails to properly control the oil temperature, the high-limit thermostat prevents the fryer from
overheating to the flash point. The high-limit thermostat acts as a normally closed power switch that
opens when exposed to temperatures above 410ºF (210°C) for CE fryers and 435-450ºF (224-232°C)
for non-CE fryers. Once opened, the high limit must be manually reset before operating the fryer.
Functional diagram of a typical millivolt system.
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