Abbreviations & Definitions - Goodman GMVM Service Instructions Manual

ABBREVIATIONS & DEFINITIONS
Pressure Switch Calibration Routine
furnace must go through a pressure switch calibration rou-
tine before it can begin its first heat cycle. This is performed
automatically by the furnace and requires no action on the
part of the installer other than to have the system compo-
nents installed completely and correctly. On the initial power
up, or any time that power to the furnace is switched off then
back on again and a call for heat is applied, the furnace will
go through a calibration routine. During the calibration rou-
tine the IFC runs the induced draft blower at different speeds
to determine the opening and closing points of the pressure
switches. It records this information and uses it as reference
points for determining the draft inducer speeds for all gas
input rates from 35% - 100%.
Before beginning a calibration routine, the IFC will check that
both pressure switches are in the open position.
· The IFC powers the draft inducer at a predetermined
speed and checks to see if the LPS has closed.
· If the LPS is not closed the IFC will increase the draft
inducer RPM in small steps until it detects a closed
LPS.
• The IFC then begins to reduce RPM until it detects
that the HPS is open.
• It records the RPM point where the HPS went open.
• The IFC then adds a predetermined amount of draft
inducer RPM to both the recorded points.
• These new RPM points are the draft inducer speed for
35% (lowest input rate) and 100% (highest input rate).
The IFC then is able to control draft inducer speed
through the IFC-VFD throughout the entire range of
modulating operation.
RPM
Closed
LPS
RPM 1
Time
Inducer Calibration Routine
A D
BBREVIATIONS AND EFINITIONS
• IFC: Integrated furnace control
• HSI: Hot surface element
The modulating
100% (Max)
Closed
HPS
RPM 2
35% (Minimum)
• LPS: Low pressure switch
• IDB: Induced draft blower
• HPS: High pressure switch
• Variable Frequency Drive (VFD): Control of the in-
duced draft blower is carried out by Variable Frequency
Drive. By varying the voltage and frequency to the draft
inducer, the RPM can be controlled. A section of the
IFC is dedicated to this task.
• Trial for Ignition Period (TFI): The period of time
between initiation of gas flow and the action to shut off
the gas flow in the event of failure to establish proof of
the supervised ignition source or the supervised main
burner flame.
• Gas Valve Sequence Period: The total period of time
of gas flow starting from the first initiation of gas to the
final action to shut off the gas before going to lockout.
• Ignition Activation Period (IAP): The period between
energizing the main gas valve and deactivation of the
ignition source prior to the end of TFI.
• Flame Recognition Period (FRP): The period be-
tween deactivation of the ignition source and the expi-
ration of the TFI.
• Flame Failure Response Time (FFRT): The period
between loss of the supervised main burner flame and
the action to shut off the gas supply.
• Igniter Warm-up Time: The length of time allowed
for the hot surface igniter to heat up prior to the initia-
tion of gas flow.
• Pre-purge Time: The period of time intended to allow
for the dissipation of any unburned gas or residual prod-
ucts of combustion at the beginning of a furnace oper-
ating cycle prior to initiating ignition. Beginning from
the moment the pressure switch is sensed closed and
lasting until the ignition source is energized.
• Inter-purge Time: The period of time intended to al-
low for the dissipation of any unburned gas or residual
products of combustion, just prior to initiating ignition
retries during the Ignition Retries sequence.
• Post-purge Time: The period of time to allow for the
dissipation of any unburned gas or residual products
of combustion at the end of a furnace burner operating
cycle. Post-purge begins at the loss of flame sense.
• Ignition Stabilization Period – The period between
sensing of the main burner flame and the transition
from the Ignition Firing Rate to the Target Firing Rate.
• Ignition Recycles: The additional attempts within the
same thermostat cycle for ignition after loss of the su-
pervised ignition source or the supervised main burner
flame.
• Ignition Retries: The additional attempts within the
same thermostat cycle for ignition when the supervised
main burner flame is not proven within the Trial for Igni-
tion Period.
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