Lennox LRP16HP Series - System Controls and Operation; Electronic Ignition

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The LRP14GE/LRP14GN and LRP16GE units include an
ignition control which controls the combustion air inducer,
gas valve and spark electrode. It receives signals from the
limit switch, the rollout switch, the pressure prove switch
and the ame sensor. The ignition control is shown in g-
ure 9. LED codes are in table 2.
Electronic Ignition
On a W1 call the ignition control checks high temperature
limit and rollout switch to make sure they are closed. The
control then veries that the pressure switch is open. If the
pressure switch is closed, the control will ash code 3 on
the LED and will wait indenitely for the pressure switch to
open. If the pressure switch is open, the control proceeds
to the 15-second pre-purge.
The ignition control energizes the combustion air inducer,
ashes a code 3 on the LED, and waits for the pressure
switch to close.
When the pressure switch has closed, the LED code 3
ash stops and the control begins the 15-second pre-
purge period. When the pre-purge time has expired, the
control begins the ignition trial.
The ignition control energizes the gas valve and spark.
The control ignores the ame sense signal for the rst
two seconds of the ignition trial. If the ame is established
within 10 seconds, the control de-energizes the spark. If
ame is not established within 10 seconds, the gas valve
and spark are de-energized and the ignition control initi-
ates a 30-second inter-purge sequence.
Approximately 30 seconds after the ame has been es-
tablished, the circulating air blower starts. The ignition
control inputs are continuously monitored to ensure that
the limit switch, rollout switch and pressure switch are all
closed, and that the ame remains established and heat-
ing demand is present.
Single-stage gas valve, single-speed combustion air in-
ducer and circulating blower remain energized. If the ther-
mostat signals a requirement for second-stage heat (W2)
on the dual fuel unit, the ignition control initiates auxiliary
or back-up heat operation.
When a signal for second-stage heat is received by the
ignition control, the control energizes the gas valves on
dual fuel units and single-speed combustion air inducer
until the demand is satised.
If a rst-stage heat demand continues after the sec-
ond-stage heat demand has been satised, the ignition
control immediately de-energizes the gas valve. Heat
pump operation continues until heating demand is satis-
ed.
When the heating demand is satised for dual fuel rst
stage, the control immediately de-energizes the compres-
sor. The combustion air inducer remains energized for a
30-second post-purge period. The circulating air blower
operates for 90 seconds after the gas valve is de-ener-
gized (GE/GN units only).
The combustion air inducer is energized for 30 seconds
at a Y1 call for cooling to clear warm humid air out of the
heat exchanger.
The ignition control LED ashes codes which indicate nor-
mal or abnormal operations. See table 2.