Dust, hair and microscopic organisms are just a few of the particles that swirl through the air inside most homes. All hot air furnaces have at least a basic air filter system built in. Usually, it’s a fiber filter, lightly coated with adhesive to help large particles stick, which collects large dust particles as the air passes through the duct system. And for most people, that works just fine.
But many people are unusually sensitive to dust and other allergens, and they need a higher level of air filtration. All of the following choices can be installed directly in the ductwork so that all of the air in your home has to pass through the filters:
Types of Particle Filters
Passive electrostatic filters are made with polypropylene fibers that pick up a static charge as air passes over them. The static charge helps to hold fine particles. These filters can be washed and reused. Passive filters work better than standard fiber filters and they fit into the filter slot of most residential furnaces.
Pleated filters use a finer mesh, which catches smaller particles. Because the finer mesh also creates more resistance to air flow, the surface is pleated to offer more area for air to pass through. Pleated filters can be from one to six inches thick. One or two inch thick filters will fit in the filter rack of most furnaces, but the thicker filters require slight alterations to the ductwork.
HEPA is short for High-Efficiency Particulate Air filters. HEPA filters take the idea of a pleated filter to its extreme limit: Hundreds of square feet of filter paper are folded into an ordinary filter frame that is several inches thick. They remove very small particles, including some viruses. Like the thickest pleated filters, some alteration to the ductwork is required. Unfortunately, HEPA filters restrict air flow so much that a larger blower is often required, and sometimes larger ductwork.
Electronic air cleaners trap the smallest particles of all. They accomplish this by imparting an electric charge to plates in the unit. Particles in the air pick up the charge when they pass over the charged surfaces, but then stick to oppositely charged plates downstream. A small amount of ozone is generated in the process, and most of this is picked up by carbon filters downstream. These filters present very little resistance to air flow, so the existing blower and ductwork can be used, and the area that collects the particles can be cleaned by simply running it through the dishwasher with no detergent.
If the primary concern is mold, bacteria, and other biological particles, then an Ultraviolet Purifier may be the best solution. UV Purifiers mount in the existing duct system with very little work, and kills microorganisms as they pass by the unit. Known as UVGI, Ultraviolet Germicidal Irradiation has been used in hospital ventilation systems to help reduce contamination, and it is now available for household use. They are completely silent and require very little maintenance.
Judging Filters and Air Cleaners
The results of standard tests can help you pick the right filter for your needs.
The chart above illustrates how the effectiveness of different filters varies depending on particle size. Two filters perform well across the entire range of particle sizes: HEPA filters and electronic air cleaners. (Ultraviolet Purifiers are not included in these test results because, technically, they don’t “filter” the air.)
To determine which filter system is right for your home or business, call Bantam Fuel to discuss your present system and any air quality issues you may have.