Most any vacuum does a reasonable job of pulling dirt off the floor if used properly. There are definitely machines that clean faster and better than others but the general principle is based on how a vacuum cleaner is used and maintained. If a vacuum cleaner that is rated excellently by expert opinions and users isn’t used or maintained properly then the machine will not be able to achieve results anywhere near to what it is capable of!!
There are many vacuum designs on the market. Some have narrow openings for dirt with small agitators, and some have wide openings. Bristle arrangements can be straight, chevron, or articulated. Some vacuums have dirt sensors. All of these features constitute the efficiency of a machine but become meaningless if not able to perform as manufactured and tested.
A dirt sensor feature on a vacuum informs the user whether or not dirt is passing into the machine as a helpful indicator of whether to continue vacuuming the same spot or move on. Although helpful a dirt sensor merely means, that particular vacuum cleaner is no longer capable of sucking in dirt. It does not necessarily mean the carpet is clean. However, if your machine is equipped with this feature you should definitely continue to move it over the surface until the indicator changes color to indicate clean—usually green.
When a vacuum’s spinning agitator brush touches the surface there is a significant change in noise and tone from the machine. This is a good thing. If your machine states automatic carpet height adjustment, then your machine is pre-set from factory to clean most any carpet and no further adjustment is necessary. If your machine has a manual carpet height adjustment then the setting can be different for any carpet in your home. Many manual height machines have 4 or 7 settings. On many medium pile carpets with a 4 setting dial, the lowest setting is the best. Leaving a higher setting for area rugs, and shags. One of the best ways to set height on a manual machine to start at the very highest. Give a pass with machine, then readjust. Find the setting where the vacuum tone just changes and go 1 setting lower, and that is usually a good spot for the machine to be. The goal is clean, groomed carpets while not restricting air flow to get in, and allowing the brush roll to rotate at proper RPM. If the height is too low, the brush roll, slows dramatically. This greatly impedes carpet cleanliness.
If you push a block of wood through a table saw too quick, the machine kicks back causing wood to break also usually causing injury. If you mow lawn too quick, the cut is very uneven, and tends to leave several blades uncut, potentially damaging the lawn as well. If you turn a stove burner on too high, the food will burn and not taste right. If you iron a garment too quick and and on high, the iron will put in more wrinkles than it removes and can completely ruin the clothing. Many dishwasher and washing machine cycles are around one hour. When a cleaning a shower, you spray the chemicals and allow time for them to work before scrubbing. This similar theory can be applied to vacuum cleaners. When dirt falls on floor or comes in from the outside and then we walk on it, the dirt becomes embedded into the surface. Hard foods, sand, stones and other objects actually cut up and shred carpet fibers when they become embedded. This is why we often see some carpet fibers cleaned up with vacuum cleaners. In many cases it’s not the vacuum destroying carpet but instead it’s just cleaning up the already cut up and shredded fiber caused by dirt. In-order for the machine to completely ensure that carpets are clean and the suction can pull in all of the harmful carpet destroying material the machine NEEDS TIME & PATIENCE. Use steady, even strokes ensuring the front of the nozzle is touching the floor the entire time with any suction and/or height adjusters set properly. The absolute minimum recommended passes is 6. Forward and back over the same spot counting as 2. For heavy traffic areas it’s recommended to vacuum ever 2-3 days, other areas about once a week.