Vulcan-Hart GR25, Service Manual

Page: 17 / 24

GR SERIES GAS FRYERS - ELECTRICAL OPERATION
F25125 (March 2003) Page 17 of 24
SEQUENCE OF OPERATION
Millivolt Controls
Refer to schematic diagram 7825.
1. Conditions.
A. Gas shutoff valve(s) on and gas
combination valve knob/extension arm in
the on position.
B. Shortening at proper level in fry tank and
below last set point temperature used.
C. Pilot lit.
1) Pilot valve coil is energized on gas
combination valve and pilot valve
opens for gas flow to pilot burner.
NOTE: Pilot flame must be sufficient to
generate 450 millivolts DC (minimum)
from thermopile.
D. Main valve coil on combination valve not
energized (valve closed).
E. Control thermostat off.
F. High limit thermostat closed.
2. Set control thermostat to call for heat.
A. Main valve coil on gas combination valve
is energized and main valve opens for gas
flow to main burners.
1) Main burners light.
NOTE: As long as the millivolts from
thermopile remain sufficient to keep the
pilot valve coil energized, and the control
thermostat is calling for heat, the main gas
valve stays open.
3. Shortening reaches set temperature and
control thermostat opens.
A. Main gas valve coil de-energized and
main valve closes.
1) Gas flow stops and main burners go
out.
4. Control thermostat cycles main burners until
thermostat is turned to off; gas valve
knob/extension arm is turned to pilot or off.
Kleenscreen Filtering System
Refer to wiring diagram 7850. Refer to Installation &
Operation manual for specific instructions on
filtering.
NOTE: The filter valve handle and the discard valve
handle are connected to a mechanical valve and
switch assembly to route the flow of oil in the
filtering system and supply power to the pump
motor.
1. Conditions
A. Fryer connected to correct supply voltage
and is properly grounded.
B. Shortening between 300
/
F and 350
/
F.
NOTE: Oil should not be filtered outside of this
temperature range. At lower temperatures the
oil is thicker which may increase filtering time
and place a greater load on the pump. At
higher oil temperatures, oil seal life is
decreased.
C. Control thermostat off.
NOTE: Control thermostat must remain off
during filtering.
D. Filter drawer assembly installed properly.
E. Filter power switch turned off.
F. Filter valve handle retracted.
1) Filter valve switch N.O. contacts
open.
G. Discard valve handle retracted.
1) Discard valve switch N.O. contacts
open.
2. Open the drain valve to the fryer section in
need of filtering and drain the shortening into
filter tank.
3. Turn filter power switch on.
A. Switch pilot light comes on.
4. Extend filter valve handle of the same fryer
section.
A. Filter valve switch N.O. contacts close.
1) Power supplied to pump motor.
B. Pump motor circulates oil through filter
until power is removed.
5. When the oil filtering process is completed,
close the manual drain valve to the fryer and
allow the fry tank to refill.
A. When all filtered oil is returned to the fryer,
retract the filter valve handle.
1) Power is removed from pump motor.
6. Turn filter power switch off.