Ecm Blower Control - Heat Controller HEV Series Installation, Operation & Maintenance Manual

Heat Controller, Inc.
The ECM fan is controlled directly by the DXM2 control board
that converts thermostat inputs and CFM settings to signals
used by the ECM motor controller. To take full advantage of
the ECM motor features, a communicating or conventional
multi-stage thermostat should be used (2-stage heat/2-stage
cool or 3-stage heat/2-stage cool).
The DXM2 control maintains a selectable operating airfl ow
[CFM] for each heat pump operating mode. For each
operating mode there are maximum and minimum airfl ow
limits. See the ECM Blower Performance tables for the
maximum, minimum, and default operating airfl ows.
Airfl ow levels are selected using the confi guration menus
of a communicating thermostat or diagnostic tool. The
confi guration menus allow the installer to independently
select and adjust the operating airfl ow for each of the
operating modes. Air fl ow can be selected in 25 CFM
increments within the upper and lower limits shown on Table
6.The blower operating modes include:
• First Stage Cooling (Y1 & O)
• Second Stage Cooling (Y1, Y2, & O)
• First Stage Cooling with Dehumidifi cation
(Y1, O, & Dehumid)
• Second Stage Cooling with Dehumidifi cation
(Y1, Y2, O, & Dehumid)
• First Stage Heating (Y1)
• Second Stage Heating (Y1 & Y2)
• Third Stage (Auxiliary) Heating (Y1, Y2, & W
• Emergency Heating (W with no Y1 or Y2)
• Fan (G with no Y1, Y2, or W)
Dehumidifi cation Mode Settings: The dehumidifi cation mode
settings provide fi eld selection of humidity control. When
operating in the normal mode, the cooling airfl ow settings are
determined by the cooling settings. When dehumidifi cation
is enabled the appropriate dehumidifi cation airfl ow is used in
cooling to increase the moisture removal of the heat pump.
The dehumidifi cation mode can be enabled in two ways.
1. Constant Dehumidifi cation Mode: When the constant
dehumidifi cation mode is selected (S1–5 on the
DXM2 control), the ECM motor will operate using the
dehumidifi cation airfl ow slections while operating in
cooling to improve latent capacity. Heating airfl ow is
not affected.
2. Automatic (Humidistat-controlled) Dehumidifi cation
Mode: When the automatic dehumidifi cation mode
is selected (S2–7 on the DXM2 control) AND a
dehumidistat is connected to the H terminal, the
dehumidifi cation airfl ows will be used in cooling
only when the dehumidistat senses that additional
dehumidifi cation is required. Heating airfl ow is not
affected.
The ECM motor includes "soft start" and "ramp down"
features. The soft start feature is a gentle increase of motor
HEV/H SERIES

ECM BLOWER CONTROL

27
Installation, Operation & Maintenance
rpm at blower start up. This creates a much quieter blower
start cycle.
The ramp down feature allows the blower to slowly decrease
rpm to a full stop at the end of each blower cycle. This
creates a much quieter end to each blower cycle and adds
overall unit effi ciency.
The ramp down feature is eliminated during an ESD
(Emergency Shut Down) situation. When the DXM2 ESD
input is activated, the blower and all other control outputs are
immediately de-activated.