Lennox EL180UHE Series Manual page 12

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 8 and table 5 for flame signal check.
1 - Set the meter to the DC amps scale.
2 - Turn off supply voltage to control.
Flame
Sensor
Flame Sensor
Wire
Integrated
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
7 - When main burners are in operation for two minutes,
Measuring Flame Signal
Flame Sensor
Terminal
(+)
Remove Sensor Wire from
Integrated Control and
Connect Alligator Clip (+)
to Terminal on Control
FIGURE 8
Page 12
to cycle system.
take reading.
TABLE 5
Flame Signal in Microamps
Normal
 1.5
0.5 - 1.4
Remove Sensor Wire from
Integrated Control
Connect Alligator Clip (−)
to Flame Sensor Lead
DIGITAL METER
Set dial to measure dc microamps
Red Collar
Indicates
Positive Lead
(+)
(−) To
flame
sensor
(+) To Control
Sensor
Terminal
Low Drop Out
 0.4
and