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HE-Series Indoor
ERV
OPERATION
6.5 NORMAL OPERATION
Normal operation of the HE4XINV units involves continuous running of the fans, shutting down
only for periodic maintenance. Various optional control devices may modulate the speed of the
fans or may shut down one or more fans, but the fans always have power and are ready to run
continuously.
Continuous operation is acceptable in virtually all conditions and the unit will not be damaged
as long as air flow occurs. If filters become completely blocked due to lack of maintenance,
airflow will be blocked and the blower motors may overheat.
Continuous operation during extreme cold weather may lead to frost.
6.4.4 Variable-Speed Units
The motors on variable-speed units also have adjustable sheaves, but they are not to be
adjusted. Speed control of variable-speed units is accomplished by adjusting either the VFDs (if
present) or the Integrated Commercial Controls (if present). For more information on adjusting
VFDs, see the manual that was shipped with the unit. For more information on adjusting speeds
via commercial controls, see the
Integrated Commercial Controller
manual that was shipped
with the unit.
6.4.3 Sheave Adjustment
All fan motors that are not controlled by a VFD are equipped with an adjustable sheave. These
adjustable sheaves must be re-set in the field to attain optimum performance of the ERV. This
adjustment is to be done after all ductwork is connected.
Adjustable sheaves are held in position on the drive motor shaft by a set screw that is normally
hidden until the belt(s) is removed. One flange is fixed-position, the others are adjustable-position.
The adjustable flanges of the sheave have a set screw located in an exposed position on the collar of
the flange.
To adjust the flanges:
u
Remove the drive belt(s)
u
Loosen the set screws on both adjustable flanges
u
IN HALF-TURN INCREMENTS, turn the adjustable flanges in or out the same number of turns
u
Tighten the set screws on the adjustable flanges, making certain that the set screws are landing
on the machined “flat” on the sheave.
6.6 EXTREME COLD OPERATION
HE4XINV units are capable of operating without internal frosting at temperatures down to
-10° F, with indoor humidity below 40%. The units can operate under more severe conditions
occasionally with little or no impact on their performance. At lower humidities, they can operate
at still lower outside temperatures without freezing the enthalpic cores.
Some condensation or even frost may form on the outside of the unit or drip off the cabinet
during very cold conditions, especially if the unit runs continuously. Exterior condensation
during extreme cold conditions can be reduced or prevented by periodically cycling the unit OFF
for several minutes to allow the cabinet to warm up.
