Vacuum Cleaner Suction Vs. Airflow

There are two vacuum performance elements you should always be keen to check

Central vacuum motor

Main central vacuum dealers have often discussed and demonstrated that the Air Watts indicated in a product brochure are not proper measurements of performance. Instead, the quality and longevity of a vacuum motor should be weighed in your cost evaluation together with any performance claims.

Notably, there are the two main vacuum performance elements to discuss in the vacuum suction vs Airflow heated debate that makes up the actual performance of a central vacuum system:

1. Airflow, expressed in CFM (Cubic Feet per Minute)

2. Suction, also referred to as vacuum, expressed in Inches of Water Lift.

A central vacuum motor is like a jet engine. Turbine propellers are spinning at thousands of revolutions per minute and, in turn, generating a remarkable amount of vacuum and producing a huge amount of Airflow. A central vacuum motor operates on a similar principle.

Even though the Airflow measurement shows how much air the central vacuum motor can move, the Suction measurement indicates the maximum pull the motor is capable of. That is determined by sucking a 2-inch column of water vertically to its maximum height in inches and hence, the term “Water Lift.”

Central vacuum motor performance is a key element that determines Suction and Airflow capacity

Central vacuum motor performance

The performance curve of a central vacuum motor has an “inverse relationship,” implying that when Airflow is at its maximum, Suction is at its weakest – and vice versa. The term Airwatts was produced to determine the ‘sweet spot’ at which Suction and Airflow co-exist at their most efficient outlet along the performance curve. Nonetheless, the maximum value falls outside the typical operating orifice of a working central vacuum system like any brochure performance claim.

The same is true for both Suction and Airflow. A central vacuum does not function at a 2-inch orifice where Airflow is at its greatest. You would be able to vacuum anything at a 0 inch sealed vacuum orifice when suction is at its peak.

Like autumn leaves blowing across an empty parking lot, it is the movement of air (Airflow) that carries dirt away in your central vacuum system. Just like in nature, it is the difference in atmospheric pressure (Vacuum) that generates both the movement and velocity of air.

Although both Suction and Airflow are needed in a vacuum system to move debris, systems with higher Vacuum potential (Sealed vacuum) have the end of hose performance in a household installation. That is because motor Airflow performance is mainly negated by restrictions found in a typical central vacuum system.

References and Resources