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EL180DFE HEATING COMPONENTS
FIGURE 6
Gaskets
Collector Box
Orifice Plate
Pressure Switch
Combustion Air Inducer
Internal Flue Pipe
Sensor
Rollout Switch
Rollout Switch
(Alternate Location)
Gas Valve / Manifold Assembly
Ignitor
5. Flame Rollout Switches (Figure 6)
Flame rollout switch (S47) is a high temperature limit. Each
furnace is equipped with two identical switches. The limit is
a N.C. SPST manual‐reset limit connected in series with
the integrated control A92. When S47 senses rollout, the
integrated control immediately stops ignition and closes
the gas valve. If unit is running and flame rollout is detected,
the gas valve will close and integrated control will be dis
abled. Rollout can be caused by a blocked heat exchanger,
blocked flue or lack of combustion air. The switch has a fac
tory setpoint of 210°F and cannot be adjusted. To manually
reset a tripped switch, push the reset button located on the
control.
6. Primary Limit Control
The primary limit on EL180DFE units is located in the heating
vestibule panel under the combustion air inducer. See figure 1.
When excess heat is sensed in the heat exchanger, the limit
will open. If the limit is open, the integrated control energizes
the supply air blower and closes the gas valve. The limit auto
matically resets when unit temperature returns to normal. The
switch must reset within three minutes or SureLight
®
control
will go into Watchguard for one hour. The switch is factory
set and cannot be adjusted. The switch may have a different
setpoint for each unit model number. If limit switch must be
replaced, refer to Lennox ProductZone repair parts list on
Lennox DaveNet®.
A flame sensor is located on the left side of the burner sup
port. The sensor is mounted on the flame rollout plate and
the tip protrudes into the flame envelope of the left-most
burner. The sensor can be removed for service (clean us
ing steel wool) without removing any part of the burners.
During operation, flame is sensed by current passed
through the flame and sensing electrode. The integrated
control allows the gas valve to remain open as long as
flame signal is sensed.
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.
