ELECTRICAL OPERATION
CONTROL SYSTEM DESCRIPTION
1.
The thermopile (TH) provides total control
voltage for this system.
A.
One side of thermopile is connected to
common (C) of high limit (HL).
B.
The other side of the thermopile is
connected to normally open (NO) contacts
(wire 4) of high limit.
C.
The common of high limit (below high limit
trip temp) is connected through normally
closed (NC) contacts of high limit, through
wire 3 (wire 3 goes to TH/TP terminal on gas
valve) to combination valve pilot connection
common.
D.
The other side of pilot valve is connected
through wire 4 (wire 4 goes to NO terminal
on high limit with red wire from thermopile)
to wire 1 (wire 1 goes from thermostat to
high limit common terminal with white wire
from the thermopile) to high limit normally
open contacts which hold pilot valve open.
NOTE:
If high limit trips, connection is made from
common to normally open contacts, turning off pilot
valve voltage. The gas valve closes.
2.
Thermostat Control
A.
One side of millivolt supply is connected
through high limit system, as described
above, to thermostat common (wire 2) of
combination valve.
B.
The other side of thermopile is connected
from normally open (common terminal on
high limit) contacts of high limit to thermostat
through wire 1 (common terminal on high
limit).
C.
When the thermostat calls for heat (closed
circuit) power from thermopile, it is then
connected to other combination valve
thermostat connection through wire 2 (to TH
terminal on gas valve).
D.
If high limit trips, thermopile is connected
across zero ohms, the output voltage of
thermopile drops to 0.0 millivolts, and the
thermostat coil of combination valve drops
out, shutting the thermostat valve.
3.
Total Shutdown
A.
When high limit trips, 0.0 millivolts will read
across both coils of the combination valve,
causing both valves to close.
B.
Pilot relight cannot be accomplished until oil
cools sufficiently to allow high limit to close.
C.
If any wire in the system is shorting, cut or
broken, the system will shut down.
SYSTEM CONDITION QUICK
CHECK PROCEDURE
1.
Use the Pilot Lighting procedure and check
millivolts (mV) at wires 3 and 4.
A.
lf the pilot lights, then pilot combination
valve and high limit are good.
B.
If the pilot will not stay lit, check high limit
and open the thermopile circuit. It should
read 500 mV; if there are Ø volts, check high
limit. If the high limit is good, replace
combination valve.
C.
Check for voltage at disconnected
thermopile. It should read 500 mV; if there
are Ø volts, replace thermopile. Check high
limit. If the high limit is good, replace
combination valve.
2.
Turn on thermostat; burners should light.
A.
If burner does not light, check voltage at
combination valve at wires 2 (TH) and 4
(TP).
B.
If correct voltage is present, then check
combination valve.
C.
If there are Ø volts, check voltage between
wire 3 of combination valve and wire 1 of
thermostat. If correct voltage is present,
then check resistance of the thermostat
contacts and continuity of wires 3 & 2.
LG Series Fryer - ELECTRICAL OPERATION
F45691 (1117)
Page 20 of 23
