Rheem RGPE series Installation Instructions Manual page 81

c. After the burners light, the remote
flame sensor must prove ignition. If
the burners do not light, the system
goes through another ignition
sequence. It does this up to 4 times
(2 attempts on low fire and 2 tries on
high fire).
d. The main blower starts on low-heat
speed 30 seconds after the flame is
proven. The furnace continues to run
on low fire until the call for heat is sat-
isfied or the 2nd stage contacts close.
If the 1st stage call for heat is satis-
fied the gas valve closes and the
induced draft motor continues running
for a 10 second post purge time. the
main blower runs for its blower off
delay (this timing is field adjustable).
See Figure 36 for switch settings
(SW2-3 & SW2-3).
Call for 2nd stage heat after 1st stage
The "R" and "W2" thermostat contacts
close, calling for 2 stage heat. The
induced draft motor switches to high
speed and the high pressure switch con-
tacts close. The gas valve switches to
high fire and the main blower switches to
high heat speed.
2nd stage heat satisfied, 1st stage
heat still required
The "R" and "W2" thermostat contacts
open. The induced draft motor switches
to low speed, the main blower motor
switches to low heat speed and the gas
valve changes to low fire. The furnace
continues to run in this mode until the
1st stage heat call is satisfied. The sys-
tem will shut down as noted in "d," under
1st stage call for heat.
NOTE: Under extreme cold conditions,
the 2-stage thermostat may call for the
furnace to cycle between 1st and 2nd
stage operation.
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