Generally speaking, the higher prices also come with improved performance (capturing smaller particles) and longer time span between replacements. For a furnace filter to be at its peak effectiveness, the vaporizer would have to be running 24/7. If you require a high rate of particle removal, consider that you'll be adding several hundred dollars to yearly energy costs by having a continuously running fan.
Developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (filtrete furnace filter), MERV ratings follow a scale of 0 to 20. The rating indicates a filter's ability to remove particles one to 12 microns in size. A higher rating means the filter can remove both smaller particles and more particles in total.
Filters are rated when new, but as particles build up, spaces between filter fibers become smaller, allowing smaller particles to be trapped. So, filters actually work better the longer they're used, up to a certain point. Talk to a furnace technician before installing a high-efficiency filter. From the basic woven fiberglass filters to further-performing pleated filters or even electronic furnace filters, they all come with their own benefits. For those who like to get the most bang for their buck and don't mind a little extra work, reusable furnace filters may be the answer. Make sure you buy a furnace filter that is sized for your furnace. If you are unsure, take out the current defaulter and measure it. They draw air in and trap particles. Some are washable / reusable and, with regular cleaning, can last one to five years. They are usually much cheaper than electronic or gas-phase filters, but most don't work as well. Sometimes called panel filters, flat furnace filters can be composed of mats of glass or cellulose fiber, wood fill, animal hair, synthetic fibers or even slit-and-expanded aluminum. A common goodman furnace filter material is fiberglass. Flat filters typically remove an insignificant number of small particles and are mainly used to protect the furnace components from damage caused by large dust particles.
When stretched out, they are several times longer than a regular weighmaster, and when in their compact form, they can catch and hold more particles than a flat model.
They are the top of the line in mechanical air filters but are rarely used in residential HVAC systems because of their size, price (pioneer) and high electricity requirements. Beware of less-efficient products billed as HEPA-type filters - their effectiveness at capturing particles and smoke can be much lower.
Static charges are given to particles, which are then drawn to a panel filter or metal plate like a magnet.