Bulletin 30-020.007
Copyright © 2019 Unico Inc. Page 8
EC MOTOR TEMPERATURE LIMITS
The Unico EC motor includes an electronic circuit
board that is sensitive to overheating if the air
temperatures surrounding the motor are above a certain
value. The motor will not function above its maximum
operating temperature. The motor life will be reduced
between the maximum operating temperature and the
normal temperature limit. Depending on the
application, this may or may not be acceptable.
Normal temperature limit. For maximum motor life,
we recommend that the Unico EC motor be limited to
applications with less than 130°F (54°C) air
temperature. Therefore, the Unico EC motor can be
used with all heat pump and electric heating
applications without problem. It may also be installed
with a hot water coil with air temperature leaving the
coil less than 130°F (54°C). This is generally with
water temperature less than 135°F (57°C) but it
depends on the water and air flow. Consult the hot
water coil specifications to determine air temperatures
based on water flow and air flow rate.
Maximum operating temperature limit. The
absolute limit for the motor is 150°F (65°C) air
temperature, above this point the motor will
automatically begin to slow down. The motor may be
used in applications with air temperature around the
motor between 130 to 150°F (54 to 65°C), typical for
boiler systems with water temperatures between 135
and 160°F (57 to 70°C). However, expect the life of
the motor to be reduced by as much as 50%. In most
applications, with unit operating intermittently, the
amount of time that the motor operates in heating is
very small so the reduction in motor life will not be
significant. Only for extended continuous heating
applications, will the reduction be noticeable. The
reduction in motor life can be minimized by using
setback boiler temperatures while operating with
maximum airflow at the highest water temperatures.
Table 2. Motor Operating temperature
UNIT ASSEMBLY
The units may be assembled either horizontally or
vertically. Refer to Fig. 1 for your particular flow
arrangement. Assemble the units’ two modules at a
time. If you use a refrigerant coil, the anti-frost switch
wires must be routed to the control box as you connect
the modules.
Anti-Frost Switch Wires. Remove the coil access
panel and unravel the anti-frost switch wires. Connect
the modules together, then feed the wires through the
bushing in the motor partition panel.
Fastening Modules Together. To fasten the modules
together tilt the units to insert the connection flange
over the mating flange as shown in Fig. 4. It may be
necessary to squeeze the units together as you are
inserting the flange to compress the rubber gaskets. If
the hook flange has a small gap, use a large flat bladed
screwdriver to pry the gap apart. Secure the modules
together with the latches, compressing the gasket
further. It is also recommended to tape the seams of
the modules after latching.
Figure 4. Module Flange Connection
Horizontal Installations
Most systems are installed in the horizontal
configuration, with the air going from right to left
when looking at the connections (as shown in figure
2). All the modules are factory set for horizontal
airflow. It is not recommended to flip the cooling
module to reverse the flow direction of the air. When
connecting the modules be sure to arrange the heating
module on the inlet (return) side of the cooling
module.
The 4860 cooling module also includes a spacer
module which has a small drip shelf (shipped loose)
that must be installed on the air exit side of the drain
pan (shown in figure 5).
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