Central vacuum systems can remove dust and dirt more effectively than conventional vacuum cleaners, keeping the air and floors a lot cleaner.
If you’re concerned with indoor air quality, you may want to take a first (or second) look at adding a central vacuum system to your IAQ package. In Canada, where windows remain shut for most of the year, these systems come standard in most new homes. Here in the United States, however, many builders still regard the central vac as an amenity and not a green building product. This opinion is changing as more builders become aware of how effective these systems can be in removing airborne irritants and allergens.
In a 2001 study evaluating the health impact of central vacuum systems on patients with house dust allergies, conducted by the University of California at Davis School of Medicine, researchers had two groups of participants use either a conventional or central vacuum system for three months and then switch to the other system. The researchers reported that in all aspects of the evaluation, including sleep, non-nasal symptoms, nasal symptoms, eye symptoms, and even emotions, the use of a central vacuum proved to be “superior,” with reported improvement in allergy symptoms ranging from 40% to 61% when participants used a central vacuum system.
Both the U.S. Green Building Council’s LEED for Homes and the ANSI National Green Building Standard (NGBS) recognize the contribution of central vacuum systems to improved indoor air quality. LEED offers one point, while the NGBS provides up to five Indoor Environmental Quality points for installing a central vacuum system vented to the outside.
Built-in Vacuum System Basics
To understand how a built-in vac would improve indoor air quality, reflect on how a conventional vacuum cleaner works. The device sucks dirt and dust off floor surfaces and captures most of that dust in a bag or canister, with the particles too fine for the filter billowing right back into the room. Even if you’re using a vacuum equipped with a HEPA (High Efficiency Particulate Air) filter, the exhaust air stirs up the dust lying on nearby surfaces, raising a cloud of irritating particles as you vacuum the room. A built-in vacuum, by comparison, captures the dirt and dust and then delivers it to a sealed canister away from the living area.
Central vacuum systems require little maintenance. Unlike conventional vacuums that leak if bags tear or become overfull, the systems have large capacity dust collectors that won’t tear or leak, so they generally won’t release particles into the air even when neglected. But to assure that absolutely no household dust is ever recycled into indoor air, the American Lung Association recommends cleaning with a central vac that vents particles to the outside of the house. Most central vac manufacturers provide this option, and many have high-quality, self-cleaning HEPA filters, such as Beam’s Gore-Tex filter system that screens particles down to 0.3 microns at 98% efficiency.
Central vacuum systems also have larger, more powerful motors than you could lug around on an upright, thereby doing a better job of deep cleaning, especially on carpets. “Central vacuums provide up to five times the suction power of a portable with 100% of the vacuumed dirt removed to a dirt canister,” says Amy Wesely, floorcare marketing manager at H-P Products.
A Three-Part System
A central vacuum system contains three major components: a power unit that holds the motor, a filtration system with a receptacle to collect the dirt, and a network of PVC pipes plumbed through the walls and floors, terminating at inlet valves where users plug in the hose for a host of cleaning tools and attachments.
In the old days, a central vacuum sweeper resembled a powerful shop vac, serving up strong suction to absorb dirt but lacking the belt-driven agitator brushes common on conventional uprights. Since the 1990s, central vacuum tools have improved. They now include powerful electric or air-driven turbine brushes, plus a wide array of convenience accessories from crevice tools and upholstery cleaners to concrete patio scrubbers and pet grooming kits.
The heart of the central vac comes at the power unit, the canister-like element that hangs on the wall and holds the motor and filtration system. Within the canister, a powerful electric motor spins a turbine, creating suction. The power of vacuum systems is measured by “water lift” and air flow. Water lift represents the sucking force the vacuum exerts when applied to a laboratory water column, gauged by how many inches the water in the test column rises. Air flow is measured in CFM, or cubic feet per minute, of air flow without resistance.
A mathematical formula called air watts combines water lift and air flow to rate the overall power (watts) generated by the vacuum. Air watts is recognized by the American Society of Testing and Materials (ASTM) as the best way to measure the actual cleaning force of a vacuum system. You won’t find the Energy Star label on any system. “As an industry, it hasn’t happened because it’s an appliance that runs intermittently without great impact on energy consumption,” says Brian Campbell, product development manager at Electrolux.
Choosing the System
The first step to selecting a central vacuum system is matching the system’s air watt rating to the size of your house. Most manufacturers offer a motor-to-house-size compatibility table to make the calculation easy. When evaluating product quality, select a system with sealed bearings (to keep the dirt out), bypass cooling (a separate stream of air that cools the motor apart from the air that draws in dirt from the home), and the longest warranty available—the longer the warranty, the more confident the manufacturer is about the product.
To qualify for LEED certification points, the filtration system should include a HEPA filter and the option to pipe the exhaust outside. While some manufacturers say the exhaust air in their system is so clean this final precaution is unnecessary, all of the leading air quality certification criteria, including LEED and NGBS, require outside venting.
Noise level is another consideration. Although central vacuum systems’ remote motor location means you can carry on a conversation while vacuuming, quieter systems, as measured in ASTM-tested decibels, indicate better quality in the components used to manufacture the product. Noise reduction usually entails a combination of better motor components, more insulation, and sturdier housing. Mufflers, which mount at the exhaust port, can be purchased both from the manufacturers and after-market accessory suppliers.
Filtration systems come in three basic types: vertical, cyclonic, and inverted. The vertical bag system resembles a conventional upright, collecting dirt and dust particles within a paper bag for disposal. The cyclonic system uses centrifugal force to separate particles from air flow, depositing dirt and most of the dust into a dirt canister for disposal. It requires no added filter, but it must be vented outdoors, as the cyclonic system will not sequester the finest particles. The inverted filter system is similar to the vertical bag, except air is drawn up and across the filter (instead of down into it), allowing gravity to “self-clean” the bag as particles drop off the medium and into the collection bucket below when the system is turned off. The cleanest systems combine cyclonic filtration with a high-quality HEPA filter.
The basic “plumbing,” the tubes and fittings that deliver suction, are generic, much like water pipe that works with any brand. In fact, one manufacturer, Hayden, makes most of the thin-wall PVC pipe and fittings used with all major central vacuum systems. Although it resembles drain pipe, central vac tubing is thinner and of a different diameter, so the two are not interchangeable. Unlike heating ducts, the length of the installation, while consuming more resources, will not appreciably reduce performance. The vacuum remains as powerful at 30 feet from the motor as 3 feet, according to Campbell.
Valve inlets open the airway or seal the system when not in use. The inlets include a low-voltage coupler, which serves to trigger the on-off switch at the motor when you depress the start button on the handle. In new construction, you can also wire for line voltage at the valve to power the agitator brushes for vacuuming carpet. In a retrofit, install the inlet valves within 6 feet of a receptacle to plug in the accessory power cord.
When laying out the valve locations, double-check to ensure you can reach all cleaning surfaces with the standard 30-foot hose. For most floor plans, you’ll need one inlet per 750 square feet of floor area. It’s best to actually survey the cleaning area with hose and handle in hand before deciding on the final location of inlets. You’ll have to supplement the central vac with a conventional lug-around if the inlets aren’t accessible all over the house.
The final consideration for central vacuuming systems is choosing the tools, which include air-powered turbine brushes for hard-surface floors and electric-motor brushes for deep pile carpet. A quiver of hand tools are available to clean crevices, window treatments, ceiling fan blades, car interiors, patio slabs, and pets.
One manufacturer, H-P Products, tackled the most daunting aspect of central vacuuming—hose management—by providing a self-retracting hosepipe. Most manufacturers offer quick-clean amenities, such as Beam’s toekick fitting that sits under a kitchen cabinet for cleaning of spills.
This may all sound like consumer-experience-driven, razzle-dazzle product development, but remember that the most important aspect of any green building component requiring human interface is use. If your central vacuuming system works well and provides convenience, then the homeowner will use it—and breathe all the better.