Heating Sequence of Operation
The integrated control initiates a pressure switch
calibration at the initial unit start-up on a call for heat. The
ignition control will also initiate a calibration any time main
is present. Additional calibrations may be initiated by the
heating sequence of operation assumes completion of a
successful calibration.
NOTE: NOTE:
Applications Using a Two Stage Thermostat
A-Heating Sequence - Control Thermostat Selection DIP
switch in "Two Stage" Position (Factory Settling)
1.
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
2.
pressure switch has closed, the combustion air inducer
begins a 15 second pre-purge in the ignition speed.
3.
After the pre-purge is complete, a 20 second initial
ignitor warm up period begins. The combustion air
inducer continues to operate at the ignition speed.
4.
After the 20 second warm up period has ended, the
gas valve is energized 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
speed is adjusted to the appropriate target rate. The
inducer will remain at the 70 percent speed as long as
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 stage recognition delay.
6.
At the end of the recognition delay and on all
subsequent calls for heat in the same heating cycle,
the integrated control energizes the combustion air
inducer at high speed. The control also checks the high
inducer speed is increased to high, the indoor blower
motor is adjusted to a speed which is appropriate for
the target rate.
7.
combustion air inducer begins a 20 second post purge
period.
8.
When the combustion air post purge period is complete,
the inducer is de-energized. The indoor blower is de-
Application Using a Two Stage Thermostat
B - Heating Sequence - Control Thermostat Selection DIP
switch in "Variable Capacity" Position
1.
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
2.
pressure switch has closed, the combustion air inducer
begins a 15 second pre-purge in low speed.
3.
After the pre-purge is complete, a 20 second initial
ignitor warm-up period begins. The combustion air
inducer continues to operate at the ignition speed.
4.
After the 20 second warm up period has ended, the
gas valve is energized and ignition occurs. At the same
time, the control module begins an indoor blower 30
second ON delay. When the delay ends, the indoor
blower motor is energized at a speed that matches
appropriate target rate. If the furnace is operating in
on subsequent cycles will be automatically adjusted
by the integrated control based on thermostat cycles.
to 90 percent. The furnace will continue this operation
demand.
Issue 2241
Page 49 of 65
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