Wiring And Sequence Of Operation - Lennox EL195DF SERIES User Manual

VII−WIRING DIAGRAM AND SEQUENCE OF OPERATION
1 − When there is a call for heat, W1 of the thermostat energizes W of
the furnace control with 24VAC.
2 − S10 primary limit switch and S47 rollout switch are closed. Call for
heat can continue.
3 − The integrated contol (A92) energizes combustion air inducer B6.
Combustion air inducer runs until S18 combustion air prove switch
closes (switch must close within 2−1/2 minutes or control goes into 5
minute Watchguard Pressure Switch delay). Once S18 closes, a
15−second pre−purge follows.
4 − The integrated control (A92) energizes ignitor. A 20−second warm−
up period begins.
5 − Gas valve opens for a 4−second trial for ignition
6 − Flame is sensed, gas valve remains open for the heat call.
7 − After 30−second delay, the integrated control (A92) energizes indoor
blower B3.
8 − When heat demand is satisfied, W1 of the indoor thermostat de−en-
ergizes W of the integrated control which de−energizes the gas
valve. Combustion air inducer B6 continues a 5−second post−purge
period, and indoor blower B3 completes a selected OFF time delay.
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