Normal Sequence Of Operation - Amana MVC96 BB Series Installation Instructions Manual

Temperature Rise Measurement
Temperature Rise Measurement
Diagnostics
Accessing the furnace's diagnostic menu provides access
to the last six faults detected by the furnace. Faults are
stored most recent to least recent. Any consecutively
repeated fault is stored a maximum of three times.
EXAMPLE: A clogged return air filter causes the furnace
limit to trip repeatedly. The control will only store this fault
the first three consecutive times the fault occurs.
NOTE: It is highly recommended that the fault
history be cleared when performing maintenance
or servicing the furnace.

NORMAL SEQUENCE OF OPERATION

Power Up
The normal power up sequence is as follows:
• 115 VAC power applied to furnace.
• Integrated control module performs internal checks.
• Integrated control module monitors safety circuits
continuously.
• The furnace enters a three minute power up delay to
make sure the system is setup properly. During this
time thermostat calls will not be recognized.
• Furnace awaits call from thermostat. 7-segment LED's
display Id L while awaiting call from thermostat.
Heating Mode
The normal operational sequence in heating mode is as
follows:
• W thermostat contact closes, initiating a call for heat.
• Integrated control module performs safety circuit
checks.
• Induced draft blower is energized on high speed for a
15-second prepurge.
SUPPLY
AIR
RETURN
AIR
Figure 65
• Induced draft blower steps to low speed following
prepurge. Low stage pressure switch contacts are
closed.
• Igniter warm up begins upon Inducer draft blower
step to low speed and presence of closed low stage
pressure switch contacts.
• Gas valve opens 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.
• Based on the furnace internal control algorithms the
gas valve and induced draft blower may continue
operating on low stage or both will change to high
stage. After a power cycle, the first gas heat call will
result in high stage operation.
• Circulator blower is energized on heat speed following
the selected blower on delay and will begin to ramp
up. Electronic air cleaner terminal is energized with
circulator blower.
• Furnace is now operating on the specified stage
determined by the internal control algorithm.
• Furnace runs, integrated control module monitors
safety circuits continuously.
• If the internal algorithm changes the call from low
heat to high heat, the integrated control module
will immediately switch the induced draft blower,
gas valve, and circulator blower to their high stage
settings.
• If the internal algorithm changes the call from high
heat to low heat, the control will immediately switch
the induced draft blower and gas valve to their low
stage settings. The circulator blower remains on high
heating speed for 30 seconds before switching to the
low heat circulating speed.
• The W terminal thermostat contacts open, which ends
the call for heat.
• The gas valve closes, extinguishing the flame.
• Induced draft blower is de-energized following a 15
second post purge.
• Circulator blower continues running for the selected
heat off delay period. The blower speed during this
period depends on the last heat call provided by the
thermostat. If the last call for heat was a call for low
heat, the air circulator motor will run on low heat
speed for the duration of the heat off delay period. If
the last call for heat was a call for high heat, the air
circulating motor will run on low heat speed for the
duration of the heat off delay period. If the last call
for heat was a call for high heat, the air circulating
motor will run on the high heating speed for thirty (30)
seconds and then switch to the low heating speed for
the reminder of the heat off delay period.
• Circulator blower and electronic air cleaner terminal
are de-energized.
• Circulator blower shuts off after the heat off delay
period expires.
• Furnace awaits next call from thermostat.
39