34
G e o t h e r m a l H e a t P u m p S y s t e m s
P R E L I M I N A RY
Tranquility
®
30 Digital (TE) Series IOM - 60Hz HFC-410A
R e v. : 3 A u g . , 2 0 1 2 B
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, an iGate™ communicating multi-
stage thermostat should be used (ATC32U**).
The DXM2 control maintains a selectable operating air
fl
ow
[CFM] for each heat pump operating mode. For each
operating mode there are maximum and minimum air
fl
ow
limits. See the ECM Blower Performance tables for the
maximum, minimum, and default operating air
fl
ows.
Air
fl
ow levels are selected using the con
fi
guration menus of
a communicating thermostat (ATC32U**) or diagnostic tool
(ACDU**). The con
fi
guration menus allow the installer to
independently select and adjust the operating air
fl
ow for each
of the operating modes. Air
fl
ow can be selected in 25 CFM
increments within the minimum and maximum limits shown in
Table 8. The blower operating modes include:
• First Stage Cooling (Y1 & O)
• Second Stage Cooling (Y1, Y2, & O)
• First Stage Cooling in Dehumidi
fi
cation Mode
(Y1, O, & Dehumid)
• Second Stage Cooling in Dehumidi
fi
cation 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 necessary to use the ATC32U** communicating
thermostat to engage the Auto Dehumidi
fi
cation feature on
units with Internal Flow Controllers. Units with Internal Flow
Controllers utilize the ‘H’ terminal on the DXM2 as an input
for an ambient temperature switch. Units without the Internal
Flow Controller option use the ‘H’ terminal on the DXM2
controller to initiate the Auto Dehumidi
fi
cation mode. Refer to
the DXM2 AOM for more information (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
fi
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.
The duration of the “ramp down” periods are adjustable from
0 seconds to 255 seconds. This adjustment is available
in the Ai
fl
ow Selection screen using the communicating
thermostat or con
fi
guration/diagnostics tool, see Figure 27.
Special Note for AHRI Testing:
To achieve rated air
fl
ow for
AHRI testing purposes, it is necessary to change the CFM
settings to rated air
fl
ow.
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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Figure 27: Air
fl
ow Con
fi
guration Screen on
Communicating Thermostat
