First of all, you need to know what measurements to look at when deciding on a central vacuum system. For example, in a cars, you compare the horsepower between engines. In a central vacuum system you compare airwatts. To figure out the airwatts, multiply the airflow (CFM) times the waterlift (sealed vacuum, “H20), then divide by the industry standard 7.5. This will give you the airwatts of the unit.
(Airflow x Waterlift) / 7.5 = Airwatts
Great, now you have an airwatt number, but you still don’t know what that means. Right? Well, an easy way to visualize this is by putting a penny in your hand with you palm outstretched, face up. Take the end of the hose and place the opening over the penny, pressing hard enough to seal off any air. Then, turn the power on. Nothing happens, right. That is because you have created a vacuum; however, a vacuum without airflow will not move anything. The central vacuum may have a high waterlift number (vacuum), but without airflow, the debris or in this case the penny will not be sucked to the canister. Now, let up on the hose by tilting it slightly so that a little airflow gets through the hose. Poof. The penny is sucked up into the dirt can. Together, airflow and waterlift create the means to whisk your dirt and debris (or in this case a penny) straight to the dirt can and out of your home.
Another important factor when comparing central vacuums is the motor’s brush life. The motor inside a central vacuum power unit contains carbon brushes that wear down as the vacuum is used. Rather than measured in years, brush life for a motor is measured in hours.