Heating Components; Ignitor; Flame Sensor; Flame Signal In Microamps - Lennox EL296UH045XE36B Unit Information

C- Heating Components

1. Ignitor

®
The SureLight ignitor is made of durable silicon nitride.
The integrated control provides 120 volts to the ignitor for a
consistent ignition and long ignitor life. Ohm value should
be 39 to 70. See figure 14 for ignitor location and figure 15
for ignitor check out.
NOTE - The EL296UHE furnace contains electronic com­
ponents that are polarity sensitive. Make sure that the fur­
nace is wired correctly and is properly grounded.

2. Flame Sensor

A flame sensor is located on the left side of the burner sup­
port. See figure 14. The sensor tip protrudes into the flame
envelope of the left-most burner. The sensor can be re­
moved for service without removing any part of the burn­
ers. During operation, flame is sensed by current passed
through the flame and sensing electrode. The SureLight
control allows the gas valve to remain open as long as
flame signal is sensed. To check flame sense signal use
the push-button found on the integrated control and go to
Field Test Mode. The menu will display the flame signal.
See table 9 for flame signal.
TABLE 9

Flame Signal in Microamps

Normal
2.6 or greater 2.5 or less
3. Gas Valve
The valve (figure 14) is internally redundant to assure safe­
ty shut-off. If the gas valve must be replaced, the same type
valve must be used.
24VAC terminals and gas control knob are located on the
valve. A wire harness connects the terminals from the gas
valve to the electronic ignition control. 24V applied to the
terminals energizes the valve.
Inlet and outlet pressure taps are located on the valve. A
regulator adjustment screw is located on the valve.
LPG change over kits are available from Lennox. Kits in­
clude burner orifices and a gas valve.
4. Flame Rollout Switches (S47)
Flame rollout switch is a high temperature limit located on
top of the burner box, one on each side.- See figure 14. The
limit is a N.C. SPST manual‐reset limit. When S47 senses
rollout, the circuit breaks and the ignition control immedi­
ately stops ignition and closes the gas valve. Rollout can be
Low Drop Out
0.6
caused by a blocked heat exchanger, flue or lack of com­
bustion air. The switch is factory set to trip (open) at 210°F
and cannot be adjusted. The switch can be manually reset.
To manually reset a tripped switch, push the reset button
located on the control.
5. Burners
All units use inshot burners. Burners are factory set and re­
quire no adjustment. Always operate the unit with the burn­
er box front panel in place. Each burner uses an orifice that
is precisely matched to the burner input. Burners can be re­
moved as a one piece assembly for service. If burner as­
sembly has been removed, it is critical to align center of
each burner to the center of the clamshell when re-instal­
ling. See more detail in Section VI- MAINTENANCE.
6. Primary Limit Control (S10)
The primary limit (S10) is located in the heating vestibule
panel. When excess heat is sensed in the heat exchanger,
the limit will open. If the limit is open, the furnace control en­
ergizes the supply air blower and closes the gas valve. The
limit automatically resets when unit temperature returns to
normal. The switch must reset within three minutes or the
SureLight control will go into Watch guard for one hour.
The switch is factory set and cannot be adjusted.
The switch may have a different set point for each unit mod­
el number. See Lennox Repair Parts Handbook if limit
switch must be replaced. When removing switch make
note of orientation. When replacing switch make sure the
three mounting holes are lined up with the screw holes in
the vestibule for correct orientation.
Primary Limit Control (S10)
Mounting Hole
Page 18
Mounting Hole
Mounting Hole
FIGURE 13