Goodman GMVM Service Instructions Manual page 55

OPERATION
Switch 14 Selects compressor setup for cooling. Factory
position is OFF. This is the correct position for a single stage
condensing unit. In this position, Y from the room thermostat
would connect to Y1 on the IFC. Full CFM selected by
switches 1 & 2 will be delivered during a Y1 call. If using a
two stage outdoor unit, move this switch to the ON position
and wire Y1 from the room stat to Y1 on the IFC, wire Y2 on
the room stat to Y2 on the IFC. This switch is ignored when
using a CTK0* communicating thermostat.
Switch 15 Selects DEHUM. Enabling this feature will re-
duce CFM in a call for cooling by 15%. Factory position is
OFF, in this position DEHUM is disabled. To use this feature
the DIP switch must be turned to the ON position and a nor-
mally closed dehumidistat be used. This switch is ignored
when using a CTK0* communicating thermostat.
Switches 16, 17, 18 These are system switches critical to
the ClimateTalk™ communicating network and must be left
in the factory enabled ON position.
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 LPS is open.
· It records the RPM point where the LPS went open
· The IFC then increases the inducer RPM by a large
predetermined step and checks to see if the HPS is
closed.
· If the HPS is not closed the IFC will increase the draft
inducer RPM in small steps until it detects a closed
HPS.
System
Air Conditioner +
Furnace
Heat Pump +
Furnace
The modulating
Furnace + Non-
Comm 1stg Air
Conditioner
For example, assume the system is an air conditioner
matched with a furnace. With a call for low stage cooling,
the air conditioner will calculate the system's low stage cool-
ing airflow demand. The air conditioner will then send a fan
request along with the low stage cooling airflow demand to
the furnace. Once received, the furnace will send the low
stage cooling airflow demand to the ECM motor. The ECM
motor then delivers the low stage cooling airflow. See the
applicable ComfortNet air conditioner or heat pump installa-
tion manual for the airflow delivered during cooling or heat
pump heating.
In continuous fan mode, the CTK0* thermostat provides the
airflow demand. The CTK02** thermostat may be configured
for one of threecontinuous fan speed settings allow for 25%,
50% or 75% airflow, based on the furnaces' maximum airflow
capability. During continuous fan operation, the thermostat
sends a fan request along with the continuous fan demand to
the furnace. The furnace, in turn, sends the demand to the
ECM motor. The ECM motor delivers the requested continu-
ous fan airflow.
F
OSSIL
This furnace can be used in conjunction with a ComfortNet™
compatible heat pump in a fossil fuel application. A fossil fuel
application refers to a combined gas furnace and heat pump in-
stallation which uses an outdoor temperature sensor to deter-
mine the most cost efficient means of heating (heat pump or gas
furnace). When used with the CTK0* thermostat, the fur-
nace/heat pump system is automatically configured as a fossil
fuel system. The balance point temperature may be adjusted
via the CTK0* thermostat advanced user menus (see CTK0*
instructions for additional information).
System Operating
Mode
Cooling
Heating
Continuous Fan
Cooling
Heat Pump Heating
Only
Auxiliary Heating
Continuous Fan
Cooling
Heating
Continuous Fan
F A
UEL PPLICATIONS
Airflow Demand Source
Air Conditioner
Furnace
Thermostat
Heat Pump
Heat Pump
Furnace
Thermostat
Furnace
Furnace
Thermostat
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