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ECM Blower Control
The ECM fan is controlled by an interface
board that converts thermostat inputs and
field selectable CFM settings to signals used
by the ECM motor controller. Fan speeds
are selected via a nine position DIP switch.
To take full advantage of the ECM motor
features, a multi-stage thermostat should be
used (2-stage heat/2-stage cool or 3-stage
heat/2-stage cool).
Note: Power must be off to the unit for at
least three seconds before the ECM motor
will recognize a speed change. The motor
will recognize a change in the CFM adjust or
dehumidification mode settings while the
unit is powered.
There are four different airflow settings from
lowest airflow rate (speed tap 1) to the
highest airflow rate (speed tape 4). The
charts below indicate settings for the ECM
interface board, followed by detailed
information for each setting.
Cooling Settings: The cooling setting
determines the cooling (normal) CFM for the
ECM motor. Cooling (normal) setting is
used when the unit is not in dehumidification
mode. Tap 1 is the lowest CFM setting,
while tap 4 is the highest CFM setting. To
avoid air coil freeze-up, tap 1 may not be
used if the dehumidification mode is
selected. Consult Engineering Design
Guide for the specific unit model to correlate
speed tap setting to airflow in CFM.
Heating Settings: The heating setting
determines the heating CFM. Tap 1 is the
lowest CFM setting, while tap 4 is the
highest CFM setting. Consult Engineering
Design Guide for the specific unit model to
correlate speed tap setting to airflow in
CFM.
HTV/HTD/HTH SERIES
ECM BLOWER CONTROL
Auxiliary/Emergency Heat Settings: The
auxiliary/emergency heat setting determines
the CFM when the unit is in auxiliary heat or
emergency heat mode. This setting is
used for units with internal electric heat.
When auxiliary electric heat is energized
(i.e. compressor and electric heat), the
greater of the auxiliary/emergency or
heating setting will be used. A "G" (fan)
signal must be present from the thermostat
for electric heat to operate. Consult the
Engineering Design Guide for the specific
unit model to correlate speed tap setting to
airflow in CFM.
CFM Adjust Settings: The CFM adjust
setting allows four selections. The NORM
setting is the factory default position. The
+ or - settings adjust the airflow by +/- 15%.
The +/- settings are used to "fine tune"
airflow adjustments. The TEST setting
runs the ECM motor at 80% torque, which
causes the motor to operate like a standard
PSC motor, and disables the CFM counter.
Dehumidification Mode Settings: The
dehumidification mode setting provides field
selection of humidity control. When
operating in the normal mode, the cooling
airflow settings are determined by the
cooling tap setting above. When
dehumidification is enabled there is a
reduction in airflow in cooling to increase the
moisture removal of the heat pump.
Consult Engineering Design Guide for the
specific unit model to correlate speed tap to
airflow in CFM. The dehumidification
mode can be enabled in two ways.
1. Constant Dehumidification Mode:
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When the dehumidification mode is
selected (via DIP switch setting), the
ECM motor will operate with a multiplier
applied to the cooling CFM settings
(approx. 20-25% lower airflow).
Heat Controller, Inc.
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Troubleshooting
