Central vacuums have been around since the 1850s and have evolved into ever-more-efficient household appliances. The systems saw their most drastic improvements in motor power and filtration during the 1990s, and many homeowners have since come to appreciate their conveniences. But the systems can also have a positive effect on a home's indoor air quality (IAQ), according to manufacturers. "Indoor air quality is becoming a much bigger issue in the marketplace," says Paul Runyon, national sales manager for central vacuum manufacturer Beam Industries.

According to the American Lung Association's statistics, 42.3 million Americans are affected by asthma and/or hay fever, generally triggered by allergies or airborne allergens such as pet dander, mold, pollen, and dust mites. A central vacuum captures dust, dirt, and allergens without stirring up microscopic particles and re-emitting them into interior spaces. "It takes all the dust and other debris, as well as the exhaust air, and gets it out of the living environment," says Robert Moffit, communications manager for ALA's Health House Program.

"They have three to five times the power of a traditional portable vacuum, and 100% of what's picked up does not recirculate back into the living area," says Carolyn Crocker, director of floor care marketing for H-P Products, maker of VacuFlo central vacuums.

While central vacuums are usually installed during home construction, most homeowners and remodelers are unaware that they can be fairly easily retrofitted into existing homes as well. Manufacturers say that a system can usually be retrofitted in just one day, with minimal disturbance to walls.

The systems consist of a power/collection unit, low-voltage wiring, PVC piping, inlet valves, and a power team (the hose and cleaning accessories). Power units are typically installed in a garage or basement, away from living spaces, and are vented to the outside of a home.

When installed during new construction, the pipes and wires are run from the power unit through the walls to most rooms, ending in an electrified inlet valve. Retrofit installations work the same way, but it is not always convenient to open walls to install the pipes and wiring.

According to Christian Reick-Mitrisin, senior product manager for central vacuum manufacturer NuTone, these components can be installed in out-of-the-way spaces, such as inside closets or following cold-air returns. "They can easily be put through stacked closets or through many kinds of walls, as long as there's reasonable access to them," Reick-Mitrisin says.

The unused corners, nooks, and crannies found in most homes can also be altered to house pipes and wiring. "Any dead space that's normally not used can be used to install and conceal central vacuum piping. You can usually do it without even breaking walls open, if you're creative enough," says Grant Olewiler, general manager for central vacuum manufacturer M-D Manufacturing.