My SmogHog or Air Cleaner isn’t sucking air. What could be wrong?

Why Isn’t My Air Cleaner Pulling in the Smoke?

One of the most common service calls we receive is:

“My air cleaner isn’t sucking up the smoke.”

Whether you operate a SmogHog®, Absolent®, MistBuster®, Tri-Mist®, Trion®, or another industrial air cleaner, there are several reasons why your system may have little or no airflow.

Below are some of the most common causes and how to troubleshoot them.

1. Blown Fuse or Tripped Overload Relay

If the blower motor is not running at all, the first thing to check is the electrical protection.

A blown fuse or tripped overload relay will prevent the motor from starting. These are often tripped due to power issues in the summer.

These components are commonly located:

• Inside the electrical enclosure on the air cleaner.
• In a nearby disconnect switch.
• In the motor starter panel.

How to Resolve It

After disconnecting and locking out the power:

• Check and reset the overload relay if it has tripped.
• Replace blown fuses with the correct time-delay fuses.
• Restart the unit and immediately verify that the motor amperage is within the motor nameplate specifications.

If motor amperage remains too high, shut the unit down immediately and determine the cause before operating it again.

2. Failed Blower Motor

If the motor has failed, airflow will stop completely.

Before replacing the motor, determine why it failed. Simply installing a new motor without correcting the underlying problem may cause the replacement motor to fail as well.

Possible causes include:

• Incorrect incoming voltage
• Phase loss
• Power quality issues
• Motor overload
• Excessive blower resistance ie filter material in the fan.
• Worn bearings
• Contactor floats in and out due to bad electrical connections. 

If the motor runs normally but is consistently overloaded, the blower speed, pulley ratio, or motor size may need to be evaluated.

3. Belt Problems

Many industrial air cleaners use belt-driven blowers.

Several belt issues can reduce airflow:

• Loose belts
• Glazed belts
• Broken belts
• Belts that have come off the pulleys
• Belts that are overtightened

Loose belts allow the blower to slip, reducing airflow.

Overtightened belts place excessive load on bearings, shortening their life.

How to Resolve It

Inspect the belt for:

• Wear
• Cracks
• Glazing
• Proper alignment
• Correct tension

Replace worn belts and correct any alignment or tension problems before returning the unit to service.

4. Reverse Motor Rotation

Reverse rotation is a common issue after a new installation or motor replacement on three-phase equipment.

If two incoming power leads are reversed, the motor will rotate backwards.

Most blower wheels produce only a fraction (20%) of their normal airflow when rotating in reverse.

How to Resolve It

Verify the blower rotation.

If the motor is turning backwards, with the power locked out, reverse any two incoming three-phase power leads.

Motor amperage can also help verify rotation:

• Forward-curved blowers generally draw higher amperage when rotating correctly.
• Backward-inclined blowers generally draw lower amperage when rotating correctly.

5. Plugged Prefilters or Baffles

Dirty metal mesh prefilters or impingement baffles can dramatically reduce airflow.

This is especially common when collecting:

• Water-soluble coolant mist
• Heavy oil mist with carbon
• Sticky rubber smoke
• Plastic processing smoke
• Dust mixed with oil

How to Resolve It

Remove and thoroughly clean the prefilters or baffles.

If the prefilters are heavily loaded, the collection cells and ionizers likely require cleaning as well.

6. Loose Pulleys or Sheaves

If a pulley loosens on the motor or blower shaft, the blower speed will decrease or stop completely.

This usually occurs when:

• A setscrew loosens.
• The shaft key slips out.
• The pulley wears over time.

How to Resolve It

If caught early:

• Replace the shaft key if necessary.
• Tighten the setscrews.
• Verify pulley alignment.

If the shaft has become worn from prolonged slipping, the shaft, blower, or motor may need to be replaced.

7. Closed Dampers

Some industrial air filtration systems include dampers for airflow control or fire protection.

These may be:

• Manual dampers
• Solenoid-operated dampers
• Pneumatic dampers
• Fire dampers with thermal links

A closed damper can severely restrict or completely stop airflow.

How to Resolve It

Locate the closed damper and determine why it is closed.

Depending on the design, the solution may involve:

• Opening the damper manually.
• Restoring air or electrical controls.
• Replacing a thermal link after a fire damper has activated.