SYSTEM OPERATION
14
•
R and W thermostat contacts close, initiating a call for
heat.
•
Integrated control module performs safety circuit
checks.
•
Pressure Sensor Verification:
The control operates
the inducer in a manner to verify the pressure sensor
null value and span operation are within specification.
If the system is operating correctly, this test takes only
a few seconds. If the system is not functioning properly,
the control times out after a maximum 90 seconds and
display the proper fault code.
•
Induced draft blower is energized for 30 second
prepurge.
•
Igniter warm up begins after 30 second prepurge
expires.
•
Gas valves open at end of igniter warm up period,
delivering gas to burners and establishing flame.
•
Integrated control module monitors flame presence.
Gas valve will remain open only if flame is detected.
•
Circulator blower is energized on high heat speed
following a fixed 30 second blower on delay. Electronic
air cleaner terminals are energized with circulator
blower.
•
Furnace operates; integrated control module monitors
safety circuits continuously.
•
R and W thermostat contacts open, completing the call
for heat.
•
Gas valve closes, extinguishing flame.
•
Induced draft blower is de-energized following a thirty
second post purge.
•
HUM terminal is de-energized.
•
Circulator blower continues running for selected heat
off delay period factory set at 120 seconds. If required
this can be changed in the field.
•
Electronic air cleaner is de-energized.
•
Furnace awaits the next call from thermostat.
Cooling Mode
The normal operational sequence in cooling mode is as
follows:
•
R, Y and G thermostat contacts close, initiating a call
for cool.
•
Integrated control module performs safety circuit
checks.
•
Outdoor fan and compressor are energized.
•
Circulator blower is energized on cool speed following
a fixed six second on delay. If required this can be
changed in the field to 45 seconds. Electronic air cleaner
terminals are energized with circulator blower.
•
Furnace circulator blower and outdoor cooling unit
run, integrated control module monitors safety circuits
continuously.
•
R, Y and G thermostat contacts open, completing the
call for cool.
•
Outdoor fan and compressor are de-energized.
•
Circulator blower is de-energized following a fixed forty
firve second cool off delay period. Electronic air cleaner
terminals are de-energized.
•
Furnace awaits the next call from thermostat.
Fan Only Mode
The normal operational sequence in Fan Only Mode is as
follows:
•
R and G thermostat contacts close, initiating a call for
fan.
•
Integrated control module performs safety circuit
checks.
•
Circulator blower is energized on low heat speed.
Electronic air cleaner terminals are energized.
•
Circulator blower runs, integrated control module
monitors safety circuits continuously.
Summary of Contents for DM80SE
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