Other Unit Adjustments; Sequence Of Operation - Lennox ELITE Series Installation Instructions Manual

Other Unit Adjustments

Primary and Secondary Limits
The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are lo-
cated in the blower compartment, attached to the back
side of the blower. These auto reset limits are factory-set
and require no adjustment.
Flame Rollout Switches
This manually reset switches are located on the baffle
plate in the burner assembly.
Pressure Switch
The pressure switch is located in the heating compartment
adjacent to the combustion air inducer. The switch checks
for proper combustion air inducer operation before allow-
ing ignition trial. The switch is factory-set and requires no
adjustment.
Temperature Rise
After the furnace has been started, and supply and return
air temperatures have been allowed to stabilize, check the
temperature rise. If necessary, adjust the blower speed to
maintain the temperature rise within the range shown on
the unit nameplate. See TABLE 15 for allowable heating
speeds.Increase the blower speed to decrease the tem-
perature. Decrease the blower speed to increase the tem-
perature rise. Failure to adjust the temperature rise may
cause erratic limit operation.
Electrical
1 - Check all wiring for loose connections.
2 - Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC + 10%.
3 - Check amp-draw on the blower motor with inner
blower panel in place.
Unit Nameplate__________Actual__________
Blower Speeds
Follow the steps below to change the blower speeds.
1 - Turn off electrical power to furnace.
2 - Remove blower access panel.
3 - Disconnect existing speed tap at integrated control
speed terminal.
NOTE - Termination of any unused motor leads
must be insulated.
4 - Place unused blower speed tap on integrated control
"PARK" terminal or insulate.
5 - Refer to blower speed selection chart on unit wiring
diagram for desired heating or cooling speed. See
Blower performance data at the end of this manual
and TABLE 15 for allowable heating speeds.
6 - Connect selected speed tap at integrated control
speed terminal.
7 - Resecure blower access panel.
8 - Turn on electrical power to furnace.
9 - Recheck temperature rise.
Heating Sequence of Operation
Electronic Ignition
The two-stage, variable speed integrated control used in
EL280UH(X)E units has an added feature of an internal
Watchguard control. The feature serves as an automatic
reset device for ignition control lockout caused by ignition
failure. After one hour of continuous thermostat demand
for heat, the Watchguard will break and remake thermo-
stat demand to the furnace and automatically reset the
control to begin the ignition sequence.
NOTE - The ignition control thermostat selection DIP
switch is
factory-set in the "TWO-STAGE" position.
Applications Using a Two-Stage Thermostat
A - Heating Sequence -- Integrated Control Thermo-
stat Selection DIP Switch 1 OFF in "Two-Stage" Posi-
tion (Factory Setting)
1 - On a call for heat, thermostat first-stage contacts
close sending a signal to the integrated control. The
integrated control runs a self-diagnostic program
and checks high temperature limit switches for
normally closed contacts and pressure switches for
normally open contacts. The combustion air inducer
is energized at low speed.
2 - Once the control receives a signal that the low
pressure switch has closed, the combustion air
inducer begins a 15-second pre-purge in low speed.
NOTE - If the low fire pressure switch does not close
the combustion air inducer will switch to high fire.
After a 15 second pre-purge the high fire pressure
switch will close and the unit will begin operation on
high fire. After 10 to 20 seconds of high fire opera-
tion the unit will switch to low fire.
3 - After the pre-purge is complete, a 20-second initial
ignitor warm-up period begins. The combustion air
inducer continues to operate at low speed.
4 - After the 20-second warm-up period has ended, the
gas valve is energized on low fire (first stage) and
ignition occurs. At the same time, the control module
sends a signal to begin an indoor blower 30-second
ON-delay. When the delay ends, the indoor blower
motor is energized on the low fire heating speed, the
HUM contacts close energizing the humidifier and
120V ACC terminal is energized. The furnace will
continue this operation as long as the thermostat has
a first-stage heating demand.
5 - If second-stage heat is required, the thermostat
second- stage heat contacts close and send a signal
to the integrated control. The integrated control
initiates a 30-second second-stage recognition
delay.
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