Dyson

Its large, transparent collection cup is easy to check and is both hygienic and quick to empty--simply pop it off, hold it over a trash bin, and pull the trigger to release the dust without having to touch it. There are no bags or filters to buy. The vacuum comes with a pre-motor filter that captures particles down to 0.1 micron (e.g., pollen) and is washable. Its post-motor electrostatic filter, which never needs replacing, traps carbon emissions from the motor. Approved for allergy sufferers by the British Allergy Foundation, the vacuum's lifetime HEPA filter doesn't clog and provides cleaner expelled air.

With its automatic carpet-height adjustment feature, this upright vacuum maintains constant contact with the floor to maximize dust pickup, and its brush bar turns off at the touch of a button to protect rugs and delicate floors. The Dyson is ideal for bare floors and carpets, with suction channeled right to the edges of the cleaner head.

Specially designed edge-cleaning whiskers, angled to reach down between the skirting board and the floor, flick dust from the edge into the airflow. Its wide channel picks up large pieces, and its mini turbine head removes pet hair from confined spaces such as from upholstery, stairs, and the car. For easier cleaning under low furniture, the low-reach floor tool attaches to the wand to clean hard-to-reach places, such as under beds and sofas. For instant stair and high-reach cleaning, the vacuum comes with a cleverly stowed, 17-foot quick-release hose. Its 35-2/5-foot power cord, along with the hose, provides a maximum reach of 52-2/5 feet. To keep carpets looking new, the included carpet care kit comes with Zorb powder to absorb dirt from carpet, as well as Dyzolv spray to remove spills and marks. The unit weighs 18-3/5 pounds and features a low handle that makes it feel lighter to carry. Designed for heavy-duty household cleaning, the upright vacuum measures 44-7/8 by 14 by 13-3/8 inches and carries a two-year limited warranty.

When the vacuum cleaner is empty, clean air flows into the machine and out through the pores of the bag. However, as soon as you start to use the machine, the bag starts to fill with dust and debris. The bag acts as a filter and the machine starts to lose suction. This is because the pores of the bag begin to clog with the dust that the machine has picked up. This restricts the airflow, which causes loss of suction power.