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Vibration
Excessive vibration may be experienced during initial start-up. Left unchecked, excessive vibration can cause
a multitude of problems, including structural and/or component failure. The most common sources of vibration
are listed below.
Many of these conditions can be discovered by careful observation. Refer
to the Troubleshooting section of this manual for corrective actions. If
observation cannot locate the source of vibration, a qualified technician using
vibration analysis equipment should be consulted. If the problem is wheel
unbalance, in-place balancing can be done.
Generally, fan vibration and noise is transmitted to other parts of the building
by the ductwork. To eliminate this undesirable effect, the use of heavy canvas
connectors is recommended.
1. Wheel Unbalance
2. Drive Pulley Misalignment
3. Incorrect Belt Tension
4. Bearing Misalignment
5. Mechanical Looseness
6. Faulty Belts
7. Drive Component Unbalance
8. Poor Inlet/Outlet Conditions
9. Foundation Stiffness
UNIT START-UP
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Backward Inclined
Forward Curved
Airflow
Airflow
Rotation Direction
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Backward Inclined
Forward Curved
Airflow
Airflow
Direction of Fan Wheel Rotation
Blower access is labeled on unit. Check for proper wheel rotation by momentarily
energizing the fan. Rotation is determined by viewing the wheel from the drive
side and should match the rotation decal affixed to the fan housing (see Rotation
Direction figures). If the wheel is rotating the wrong way, direction can be reversed
by interchanging any two of the three electrical leads.
Check for unusual noise,
vibration, or overheating of bearings. Refer to the Troubleshooting section of this
manual if a problem develops.
Fan RPM
Supply fan and exhaust fan will have an adjustable motor pulley (on 15 HP and
below) preset at the factory to the customer specified RPM. Fan speed can be
increased or decreased by adjusting the pitch diameter of the motor pulley. Multi-
groove variable pitch pulleys must be adjusted an equal number of turns open or
closed. Any increase in fan speed represents a substantial increase in load on the
motor. Always check the motor amperage reading and compare it to the amperage
rating shown on the motor nameplate when changing fan RPM. All access doors
must be installed except the control center door. Do not operate units with access
doors open or without proper ductwork in place as the fan motors will overload.