If Central Vacuums are So Strong, Where Does the Air Come From?
Under normal operating conditions, a typical central vacuum will move about 40-100 CFM (airflow) if used with a power brush on carpet. An avg. 2,500 sq. ft. home contains appx. 20,000 cubic ft. That would equate to replacing the entire amount of air in the house in about 3 to 8 hrs. Vacuuming for 30 min. would suck up 6 to 6.25% of the air in the home. But where does that air come from? It comes from the outside. But how does it get in? Our homes are not so tight that the windows implode when we run the vacuum too long! Air must come through microscopic holes and pores in every surface. It comes through the drywall, flooring, windows, and doors. One open door for 10 seconds could bring in 1,400 cubic ft. of air (or 7%)—this is estimated from a person walking in at 4 mph and the airflow associated at a 7′ x 3.6″ opening. If we were really concerned about this we would air-lock the doors to our homes!
It is true that outdoor air has less particles per million. But they often contain pollens and other irritants. For the most part, these agents are filtered out as the air enters the home. This is because airflow from the vacuum into the home through the microscopic permeations is of such a small total volume that these bothersome particles cannot come in. Indeed, they can hardly move. When a vacuum nozzle is set two ft. from a dust column, the dust will barely move!
All this to say that homes really can be cleaned extremely well. And by far, a central vacuum is the best appliance for maintaining the cleanest home possible, since it removes much more dirt than conventional vacuums. For more information, visit MD’s health facts page.