Fan Installation

Proper fan installation is critical for achieving rated performance, minimizing noise, and ensuring long-term reliability. Poor installation practices can waste significant energy through system effect losses and cause premature equipment failure.

Pre-Installation Planning

Site Verification

Before installation, verify:

• Foundation/Structure: Adequate capacity for fan weight plus operating loads
• Space Requirements: Clearance for maintenance, motor removal, belt access
• Electrical: Correct voltage, phase, and amperage availability
• Ductwork: Proper size and routing for connections
• Access: Paths for equipment delivery and future service

Equipment Inspection

Upon delivery:

1. Check for shipping damage
2. Verify nameplate data matches specifications
3. Rotate shaft by hand to check freedom
4. Inspect bearings, sheaves, belts
5. Confirm accessories are included

Mounting and Support

Vibration Isolation

Select isolation based on fan speed and type:

Isolation Types:

• Rubber-in-shear mounts
• Steel spring isolators
• Combination spring-rubber
• Inertia bases for critical applications

Structural Considerations

Design supports for:

• Static weight (fan + motor + base)
• Dynamic loads (rotating unbalance)
• Seismic requirements (code-dependent)
• Wind loads (outdoor installations)

Housekeeping Pad

Concrete pad requirements:

• Minimum 4" thick
• Extend 6" beyond base
• Level within 1/8" per 10 ft
• Anchor bolt templates
• Allow concrete cure before mounting

Alignment

Belt-Driven Fans

Sheave Alignment:

1. Check shaft parallel: <0.5° angular misalignment
2. Verify sheave planes aligned: Straightedge or laser
3. Confirm shaft distances match belt requirements
4. Adjust motor position as needed

Belt Tensioning:

$$Deflection = \frac{Span}{64}$$ (force at mid-span)

For V-belts, apply 10-15 lb force perpendicular to belt; measure deflection.

Belt Installation:

• Never force belts over sheaves
• Match belt sets (matched lengths)
• New belts may stretch—recheck after 24-48 hours
• Replace belts in complete sets

Direct-Driven Fans

Coupling Alignment (when applicable):

• Angular: <0.001" per inch of coupling diameter
• Parallel: <0.002" offset
• Use dial indicators or laser alignment tools
• Document alignment readings

Ductwork Connections

System Effect Prevention

Poor connections cause significant performance loss. Follow AMCA 201 guidelines.

Inlet Requirements:

Outlet Requirements:

• Minimum 2.5 duct diameters straight
• No abrupt expansion
• Elbow turn in direction of fan rotation
• Avoid immediate branch takeoffs

Flexible Connections

Isolate fan vibration from ductwork:

Installation Guidelines:

• Length: 4-6 inches
• Orientation: Follows natural movement
• No twist or stretch installed
• Rated for pressure and temperature
• Fire-rated where required

Duct Sealing

Ensure airtight connections:

• Gaskets at flanged connections
• Sealant at slip joints
• Pressure test critical systems
• 4% leakage maximum (Class 3 per SMACNA)

Electrical Connections

Motor Wiring

• Verify voltage, phase, frequency match nameplate
• Use correct wire size per NEC
• Install disconnect within sight of motor
• Ground properly
• Provide motor overload protection

VFD Installation

For variable frequency drives:

• Follow manufacturer carrier distance requirements
• Use shielded cable if specified
• Install line and load reactors as required
• Verify grounding per VFD manual
• Set parameters before startup

Control Wiring

• Separate from power wiring
• Use shielded cable near VFDs
• Install safety interlocks
• Test emergency stop function

Pre-Startup Checks

Mechanical Verification

1. Remove shipping blocks/restraints
2. Verify all bolts tightened
3. Check bearing lubrication
4. Inspect belt tension and alignment
5. Ensure guards in place
6. Verify rotation direction (bump start)
7. Check dampers operate freely

Clearances

Confirm:

• Wheel-to-inlet clearance per drawings
• Belt guard clearance
• Access door security
• Drain connections (if applicable)

Safety Equipment

• Guards on belts, couplings, sheaves
• Screens on open inlets
• Warning labels
• Lockout/tagout provisions

Startup Procedures

Initial Startup

1. Pre-check: Complete all verification items
2. Bump Test: Verify rotation direction
3. Short Run: 30-second run, check for unusual noise/vibration
4. Extended Run: 15-30 minutes, monitor bearing temperature
5. Full Load: Operate with system under load

Performance Verification

Measure and record:

• Motor amperage (vs. nameplate)
• Fan RPM
• Inlet and outlet pressures
• Bearing temperatures
• Vibration levels

Vibration Acceptance

Per AMCA 204 / ISO 14694:

Documentation

Record and file:

• All alignment readings
• Belt tension settings
• Motor amp readings
• Operating pressures
• Vibration data
• Startup date

Common Installation Errors

Errors to Avoid

1. Backward Rotation: Always verify before full speed
2. Missing Isolators: Causes vibration transmission
3. Twisted Flex Connections: Restricts airflow, fails prematurely
4. Tight Belts: Causes bearing overload
5. Loose Belts: Causes slipping, wear, inefficiency
6. Inlet Obstruction: Blocks airflow, reduces performance
7. Short Outlet Duct: System effect losses

Troubleshooting

Proper installation practices ensure fans deliver rated performance while operating quietly and reliably throughout their service life.