Lennox EL196UH030XE24B Information page 12

Primary Limit Location and Heat Exchanger
Install limit face down
FIGURE 7
4. Gas Valve (Figure 8)
The EL196UHE uses an internally redundant valve to assure
safety shut‐off. If the gas valve must be replaced, the same
type valve must be used.
24VAC terminals and gas control switch are located on
top of the valve. All terminals on the gas valve are con­
nected to wires from the ignition control. 24V applied to the
terminals opens the valve.
Inlet and outlet pressure taps are located on the valve. A
manifold adjustment screw is also located on the valve. An
LP/Propane changeover kit is available.
MANIFOLD PRESSURE
ADJUSTMENT SCREW
(under barbed fitting)
INLET
PRESSURE
PORT
GAS VALVE SHOWN IN ON POSITION
FIGURE 8
5. Flame Sensor (Figure 6)
A flame sensor is located on the left side of the burner sup­
port. The sensor is mounted on the front burner box plate
and the tip protrudes into the flame envelope of the left-
most burner. The sensor can be removed for service (use
steel wool only to clean) without removing any part of the
burners. During operation, flame is sensed by current
passed through the flame and sensing electrode. The igni­
tion control allows the gas valve to remain open as long as
flame signal is sensed.
NOTE - The EL196UHE is polarity sensitive. Make sure
that the furnace is wired correctly and is properly grounded.
A microamp DC meter is needed to check the flame signal
on the integrated control.
Flame (microamp) signal is an electrical current which passes
from the integrated control to the sensor during unit operation.
Current passes from the sensor through the flame to ground to
complete a safety circuit.
To Measure Flame Signal - Integrated Control:
Use a digital readout meter capable of reading DC micro­
amps. See figure 9 for flame signal check.
1 - Set the meter to the DC amps scale.
2 - Turn off supply voltage to control.
3 - Remove sensor wire from integrated control.
4 - Connect (-) lead to flame sensor wire.
5 - Connect (+) lead to Terminal FS on integrated control.
6 - Turn supply voltage on and close thermostat contacts to
cycle system.
7 - When main burners are in operation for two minutes, take
reading.
6. Ignitor (Figure 6)
EL196UHE units use a nitride ignitor made from a propri­
etary ceramic material. To check ignitor, measure its resist­
ance and voltage. A value of 39 to 70 ohms indicates a
MANIFOLD
good ignitor. Voltage to the ignitor should be 102 - 132VAC.
PRESSURE
See figure 10 for resistance and voltage checks.
OUTLET
PORT
Page 12