Specifications

6
Pro-Series
Controls
Supply & Exhaust Airflow Dampers
All outdoor Pro-Series units have airflow dampers on
the outdoor air intake and exhaust air outlet that are field
adjustable.
All indoor Pro-Series units have airflow dampers on the
outdoor air intake only. The exhaust air damper is duct
mounted, and provided by the contractor.
To adjust the outside airflow damper, turn the unit off
and open the access panel. Locate the outside airflow
damper actuator inside the unit on the left side. Loosen
the two end stops c and d with a No. 2 Phillips head
screwdriver. Move the stops to the desired positions and
retighten the screws. To test the correct position of the
stops, while depressing the release button
e on the actua-
tor, move the damper to the fully open and closed posi-
tion. Readjust the stops as necessary. The actuator will
automatically open the damper to the set position when-
ever the unit is running and will close the damper to the set
position when the remote unit start/stop (by others) is
off. Note, the actuator needs power to close, therefore it is
not recommended that the unit be turned off by discon-
necting the power to the unit. This may leave the actuator
in a open position, which may not be desirable.
Figure 7.Figure 7.
Figure 7.Figure 7.
Figure 7. Location of the outside air damper and
optional actuator.
To adjust the exhaust airflow damper, turn the unit off
and remove the nut/bolt stops on both sides of exhaust
hood. Reposition the nut/bolt stops in the desired ad-
justing holes and retighten. Be sure to use matching ad-
justing hole on both sides of the exhaust hood. Readjust
the stops as necessary to obtain the desired airflow. The
exhaust airflow damper will automatically open to the set
position when the exhaust fan is on, and close when the
exhaust fan is off.
Figure 8. Figure 8.
Figure 8. Figure 8.
Figure 8. Diagram of exhaust hood
damper.
Pro-Series
Adjusting Holes
Nut/Bolt Stop
Exhaust Damper
Exhaust Hood
1 EndStop
2 EndStop
Release
Button
3
Basic Package
The basic Pro-Series unit ships with no controls. The
standard wiring package provides connections for the start-
ing/stopping of the complete unit, supply fan and the
energy wheel. The connections are shipped with factory
jumpers installed. Remote control of any of these op-
tions can be achieved by removing the correct factory jumper
and installing a contact in its place. The contact should be
capable of handling 24V power at 2 amps. (See appropri-
ate 1Ø or 3Ø circuit diagram on pages 8 thru 12). It is
strongly recommended that a remote unit start/stop
contactor (supplied by others) be used to turn the unit on
and off. This allows the outdoor air damper to fully close
when the unit is off.
Optional Electric Preheat Frost Control
For applications where the outdoor conditions do not
exceed -10°F and where the indoor design conditions do
not exceed 70°F and 25 percent RH, the energy wheel can
operate at full capacity and will not frost. For colder design
conditions or buildings with higher humidity levels, frost-
ing of the wheel can be prevented by providing a modest
amount of preheat to the outdoor air. The amount of
preheat required is small and is not intended to raise the
outdoor air temperature above the freezing point. It is
only necessary to keep the exhaust air temperature above
the dew point. This prevents condensation on the wheel
so that all the moisture transfer occurs in the vapor phase.
The preheat control option includes a finned tube elec-
tric coil mounted on the outdoor air intake of the unit, an
SCR controller and a temperature sensor mounted in the
outdoor air plenum. The temperature for the controller is
set to the minimum temperature of the outdoor air re-
quired to prevent condensation at the design indoor tem-
perature and humidity. This is done by plotting a line on
the psychrometric chart from the indoor design condition
down to the coldest temperature that does not cause the
operating line to intersect the saturation curve on the chart.
As stated above, for inside conditions of 70°F and 25
percent RH, this temperature is about -10°F.