User Guide

37
Design Guide - HZH/HZV Series
ECM Blower Control
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
multi-stage thermostat should be used (7602-457).
The DXM2 control maintains a selectable operating airow
[CFM] for each heat pump operating mode. For each
operating mode there are maximum and minimum airow
limits. See the ECM Blower Performance tables for the
maximum, minimum, and default operating airows.
Airow levels are selected using the conguration menus of
a communicating thermostat (7602-457) or diagnostic tool
(7602-444). The conguration menus allow the installer to
independently select and adjust the operating airow for
each of the operating modes. Air ow can be selected in 25
CFM increments within the minimum and maximum limits
shown in the ECM Blower Performance Table. The blower
operating modes include:
• First Stage Cooling (Y1 & O)
• Second Stage Cooling (Y1, Y2, & O)
• First Stage Cooling in Dehumidification Mode
(Y1, O, & Dehumid)
• Second Stage Cooling in Dehumidification Mode
(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)
It is highly recommended that 7602-457 or 7602-444
be used to set dehumidication mode electronically.
Dehumidication can NOT be selected when using a non-
communicating thermostat with a vFlow
®
unit with Internal
Flow Controller (pump). For dehumidication settings on
other units using the non-communicating stat, refer to DXM2
AOM (part #97B0003N15).
The ECM motor includes “soft start” and “ramp down”
features. The soft start feature is a gentle increase of motor
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 efciency.
AIRFLOW SELECTION
CFM
HEAT STAGE 1 600
HEAT STAGE 2 750
AUXILIARY HEAT 850
EMERGENCY HEAT 850
COOL STAGE 1 525
COOL STAGE 2 700
COOL DEHUMID 1 425
COOL DEHUMID 2 550
CONTINUOUS FAN 350
HEAT OFF DELAY 60
COOL OFF DELAY 30
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Airow Conguration Screen on Communicating
Thermostat
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.
The ramp down feature (also known as the heating or
cooling “Off Delay”) is eld selectable by the installer. The
allowable range is 0 to 255 seconds.