A central vacuum is a type of home filtration system that improves interior air quality by removing dust, allergens, and waste particles from indoor air. Compared to the portable vacuum cleaners that are used to clean floors and carpets, stationary central vacuum systems keep rooms cleaner; they filter air by depositing dust and dirt in a disposable bag or canister thereby minimizing the amount of dust that re-circulates back into the living area.

There are three types of central vacuum systems:

1. Paper/cloth bag

Disposable paper bag systems are the most common type of central vacuum unit. Dust and airborne waste (mold spores, pet dander, lint, bacteria, dirt, fabric fibers etc.) are suctioned into the system via outlets located in each room and deposited in a paper or cloth bag housed in a canister. The bag traps and retains the debris so that the canister itself stays clean. This type of system may or may not expel exhaust air outside. Every 1 to 2 years, the full bag is taken out and replaced with little or no exposure to the refuse. With paper/cloth bag systems, replacement bags must be purchased.

2. Bagless with filter

With bagless central vacuum systems, dust is suctioned in and deposited in a canister. When the system is shut off, the heavier dust drops to the bottom of the canister and the lighter dust is trapped by a permanent filter. The filter prevents the dust from re-circulating back into the house or entering the motor. Exhaust air may or may not be directed outside through a vent. The canister needs to be emptied and cleaned every 3 to 6 months, at which time, excess dust also needs to be washed or shaken off of the filter. Cleaning and emptying the canister involves exposure to the refuse and so this system is not recommended for people with allergies and asthma.

3. Bagless true cyclonic

With bagless true cyclonic systems, dust and waste are suctioned into the system with tornado-like force where the heavier debris falls down into a canister while the lighter debris goes through the motor and outside. Exhaust air is always vented outside with this type of system. The canister needs to be cleaned regularly―every 2 months― to maintain suction.