Why Does My Dust Collector Lose So Much Suction?

Disclaimer: Obsessed Woodworking is reader-supported. I may receive a small commission if you purchase anything through my site.

A properly functioning dust collector or shop vac system in your workshop is necessary for shop cleanliness and convenience – and your health.  It is as important as wearing safety goggles and a mask that covers both your mouth and nose. 

But when the dust collector system is not functioning correctly, and your shop is dusty and dirty, you’ll need to devote more and more time to its cleaning by hand.  The dustpan and brush no longer sit unused in the broom closet, and you lose valuable production time on your projects.

Wood dust is a real and genuine health concern, and dirty floors littered with chips can become a safety concern.  For the home DIYer with a shop in the basement or garage, that also leads to things get tracked into the home, and that means a second vacuum cleaning.

Let’s look into this a little bit and see how we can help you.

Dust Collector Troubleshooting

As in any troubleshooting, the first step is to identify the symptoms. 

  • Has the sound of the dust collector system changed?  Is the system whistling, or do you hear the sound of air rushing where there was none before?
  • Do you notice a new vibration to the system?  Are flex hoses shaking or rattling where they did not before?
  • Does the engine seem to be straining? 
  • Does the hose at a particular tool seem to be weaker?  Not picking up as much particulate as before, suggesting a decrease in suction pressure?

The answers to these questions will help in both diagnosing the problem and in locating its source.  They can also tell you what corrective steps to take to bring back the system’s peak capacity performance.

Static Pressure in a Dust Collector

Think of static pressure in a dust collector as the resistance the air meets as it travels through the system.  The greater the resistance, the less suction generated, meaning less debris gets taken away – – dust, shavings, chips.

Static pressure is a normal part of every dust collector system. It is the greater resistance to that pressure that reduces the suction power.

The dust collector filters of a system cause static pressure.  But, a dirty filter creates greater resistance, and this will lead to a reduced suction.

The system fan determines the air pressure generated, of course.  There are a few possible causes of fan failure to generate the necessary air pressure, which should be part of your system inspection.

Elbow joints in a dust collector system cause static pressure, too.  An excessive number of elbow joints in relation to the CFM (cubic feet per minute) force of the engine might also lead to greater resistance and reduced suction.

The amount of flexible duct length used in a dust collector system can also cause a loss of suction.  One foot of flex hose has nearly the same loss of suction as 10 feet of straight duct pipe. 

Understanding static pressure in a dust collector system makes both diagnosis and the cure easier to find.  Let’s now talk about the corrective steps to take based upon some of those diagnoses.

How To Increase Suction On Your Dust Collector

Following the list we just outlined, let’s talk a little bit about each.

Filters. A dust collector filter that isn’t doing its job properly will create static resistance, and air pressure will drop at the collection point(s) in your system, i.e., at each power tool station.  Check the filter for holes, and give it a good and thorough cleaning.  Be sure to follow the manufacturer’s instructions in that cleaning.  Test the system after cleaning and ensure the suction strength is where it should be based upon your system.  If it is not, it’s time to replace the filter.

Fan.  The exhaust fan might not be turning fast enough and with sufficient strength to move air through the system.  Check that the fan belt is intact and not slipping.  Check the fan blades for excess buildup of material that may be causing the fan to run slower than it should.

Elbow Joints And Flex Hose.  This actually is a pre-install issue to consider.  The design of the system is crucial to its proper performance.  An excess of elbow joints or too much flex hose may be affecting the system performance by generating less air pressure than you expected.  Shorter hose as part of a system adjustment may be the solution here.

Not in that list, but nonetheless some important considerations include:

  • Faulty Solenoid Valve.  A solenoid valve is an electrically controlled valve in your system.  Inside the valve is a solenoid, an electrical coil with a plunger that opens and closes the valve through which air will move.  Perhaps it is stuck open, which will reduce the air pressure and cause a loss of suction.  This should be investigated.
  • Leaks.  Check all connections and hose inlets along the system ductwork and make sure they are tight and sealed.  Duct tape or silicone caulk can be used to make sure they are air tight and not leaking.  Just a few tiny holes along the way can contribute to a noticeable loss of suction.
  • Inlet Ducts.  Check for obstructions or debris collection and remove anything that doesn’t belong there.  Also, make sure the connections are secure and the right fittings were used for them. 

A Good Start

Listen for new noises.  Feel the system for new vibrations.  Notice if the reduced suction is at just one tool station or is system-wide. 

These checkpoints and possible solutions are not intended to be the complete list for curing air pressure reduction and suction in your dust collector system.  But, it’s a good start, and in most instances, you can both determine the cause and effectuate the cure. 

Please leave a comment to join the discussion