Wet dry vacuum filters and suction

Reviewers give a lot of weight to how well a shop vacuum captures dust -- and whether it uses bags or filters to protect the motor and keep the dirt in the tank. It's frustrating to vacuum dust only to see a lot of it exhausted right back out, and experts at the Occupational Safety and Health Administration warn that lung damage can result from breathing in wood dust, sheetrock dust or other very fine particles.

If you pick a wet dry vac that doesn't include a HEPA or Gore-Tex filter to capture very small particles, you may be able to buy one as an accessory (*Est. $30). It's also a good idea to make sure you pick a wet dry vac for which fine-particle dust bags, often called sheetrock bags, are available. To further minimize dust exposure, select a wet dry vac with a self-cleaning filter; some wet dry vacs monitor the filter and clean it automatically when needed.

Although the majority of wet dry vacuums have adequate suction, some have more problems with emissions than others. In some cases, this can be corrected by using an add-on filter, but on some models, the lids simply don't fit tightly enough.

While many modern shop vacuums use the same filter for both wet and dry vacuuming tasks, some models' filters are for dry vacuuming only and need to be removed before wet vacuuming. Such shop vacuums may also require a foam filter sleeve or some other type of special filter for wet pickup. Be sure to consult your wet dry vac's manual to ascertain its filtration needs prior to use.

Features to consider:

Reviewers suggest keeping the following in mind when choosing a wet dry vacuum:

  • Look for a capacity that matches your needs. For collecting wood chips or other big cleanups, look for a 16- to 20-gallon tank. For most workshops and households, 10- to 14-gallon models have plenty of capacity, are easier to store and move around, and still offer adequate suction. For cleaning a house or car, smaller wet dry vacs with tanks that hold 5 or 6 gallons are easier to transport. Portable 1- to 3-gallon vacuums offer the most convenience, but they provide a lot less suction. Also consider storage space; different shop vacuums of equal capacity vary in height and shape, so some fit better in a closet than under a workbench or on a shelf.
  • Consider your vacuuming needs before deciding on a hose diameter. For general workshop pickup, such as vacuuming wood chips and shavings, experts recommend a 2.25- to 2.5-inch hose. Smaller hoses tend to clog. However, if you're using power tools in a workshop, you'll need a smaller, flexible hose that adapts to the dust ports on your tools. Many reviewers recommend that workshops include a tool-triggered shop vacuum for collecting dust, plus a larger consumer-grade model for cleaning up big wood chips and other debris. Extra-long hoses are available for most models, but in most cases this reduces suction.
  • Choose a model with a two-stage bypass motor; they last longer. This can make a difference if you plan to use the shop vacuum for extended periods as a dust collector. If you only plan to use a shop vacuum for short periods, it's not as important.
  • Know how much cleaning the filter requires. Some filters are easier to clean. Bosch, Porter-Cable and Festool wet dry vacuums offer the most convenience with their built-in filter shakers, which can be engaged without opening the units. Bosch and Porter-Cable wet dry vacuums also have separate filter doors, allowing you to remove the filter to rinse it off without opening the larger canister.
  • Think about noise level. The best shop vacuums are so quiet that you can carry on a conversation while using them, and no ear protection is needed. Most newer wet dry vacs have built-in mufflers, but they still vary greatly in sound level. Some experts say sound doubles with every six decibels. Most experts recommend wearing ear protection at 85 decibels, but it's wise to err on the side of caution. With tool-triggered wet dry vacs, remember that the noise level is increased by the sound of the attached tool.
  • Make emptying liquids easy with a drain valve or spout. Without one of these, you'll have to take the lid off and tip the tank to empty it, Remember, a big shop vacuum with a full tank of liquid can be heavy; if you plan to suck up liquids regularly, a drain plug is a must-have.
  • Opt for a shop vacuum with a pump?  If you plan to vacuum liquids frequently.  You can also invest in a pump as an accessory.
  • Ease transport with wide-set wheels and a low profile. Both prevent tipping. If you have to haul your vacuum up and down stairs, models with large back wheels and a handle are easier to use.
  • Make storage convenient with features like cord wraps and onboard attachment storage. Users note that these features don't always work as well as advertised. It's a good idea to read owner reviews of models you're considering.
  • Proceed with caution when it comes to models with a blower. Wet dry vacs that double as blowers are noisy and tend to exhaust more dust. Reviewers warn that when you use them to clean a very dusty room, they blow around the dust you're trying to vacuum. Some models feature removable lids that double as blowers, though these get mixed reviews for convenience.
  • Factor in the cost of accessories. Many of the tool attachments, filters and dust bags designed for consumer-grade shop vacuums can be used on more than one brand, but higher-end wet dry vacs often require more expensive supplies. You may also want to budget for extra accessories -- not just dust bags or filters, but a longer, bigger or more flexible hose, or more extension wands for reaching high ceilings.

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