Keep Indoor Air Clean and Comfortable
Different Types of Filters and Which is Most Efficient
This is the most common type of furnace filter for residential heating and cooling systems. They are flat, usually rectangular or square, which makes them look like panels, hence the name. Panel filters protect vital system parts like motors, coils and fans from debris and dust, but they do not do much to purify the air inside your home. Panel filters should be replaced every year, but may need more frequent replacement if you live in a particularly sandy or dusty area.
These filters remove particles from the air using static electricity. As air passes through the filter, two layers charge dust and debris with static electricity. When the charged particles pass through the two back layers, which have an opposite charge, the dirt is attracted to the opposing charge and sticks to the filter before it has a chance to enter the air inside your home.
Pleated filters are more efficient than standard panel filters and as efficient as electrostatic filters. Because these filters are pleated, they have more surface area, so they can collect more particles and filter air over a greater area.
Made of foam, washable filters are one of the most economical choices because they can be removed, washed and replaced over and over again. There is no need to spend a fortune on replacement filters every few months. Washable filters are mainly limited to use in small HVAC systems, such as window air conditioners.
Once only used in hospitals and restaurants, HEPA filters are becoming increasingly popular for residential use because of their high efficiency. An HEPA filter can remove 99.97% of all mold, dust and allergens from the air and can be installed not only in HVAC systems, but also in appliances like vacuum cleaners and dehumidifiers.
Choosing the Most Efficient Filter
Furnace filters are rated using the Minimum Efficiency Reporting Values (MERV). MERV ratings are an industry-wide system of standards that determine the efficiency of air filters. Ratings rank from 1 to 16, with 1 being the least efficient and 16 being the most efficient. The higher the MERV rating, the more particles the filter is capable of trapping.
However, buying an air filter is not as easy as simply choosing the one with the highest MERV rating. Filters with a high MERV rating create more airflow resistance, which means that air slows down as it moves through the filter. This can force your heating and air conditioning system to overwork, which defeats the purpose of installing an energy efficient air filter. Be sure to choose a filter with a MERV rating that your system can handle.
You should also be careful when purchasing electrostatic filters with high MERV ratings, as these filters lose a significant amount of efficiency as they collect more and more debris. Compare filters using the ‘discharged MERV’ rating on the product packaging for a more accurate assessment.