Furnace filters are made to gather and collect dust from the air. Other things that they can catch are mold spores, and some can even catch cigarette smoke. Since the quality of air can be up to 5 times worse inside your home compared to the air that is outside, it is extremely important that you keep a clean furnace filter in the air handler. As I have stated before the air handler is almost always located somewhere in the home, whether it be in the attic, or in a small closet in a hallway, the furnace filter will work best if it is installed right on the evaporator coils. Some set ups have the furnace filter placed in a grill that is several feet away from the evaporator coils, but in my experience placing it in the slot that it was made for right next to the evaporator coils will be the best.
MERV Ratings on Furnace Filters
The MERV (Minimum Efficiency Reporting Value) is the way that furnace filters are rated. The MERV ratings are numbered 1 through 16, 16 being the most efficient. Most households that are out there have furnace filters that have a MERV rating ranging from 1 to 4, this is not very efficient, as they only catch a small percentage of dust and particles, there efficiency is rated less than 20 percent. Spun glass and fiber HVAC air filters are the common ones that have the low rating, and they are usually disposable. These are the cheapest HVAC air filters that you can get, and they are also the least efficient.
Pleated HVAC air filters are a bit better than the fiberglass and spun glass ones, and they can have a MERV rating that is anywhere from 5 to 12. Remember now just because you go and get an HVAC air filter that has the highest rating does not necessarily mean that it is going to be the best choice for you. As the efficiency of the HVAC air filter increases, the air flow through it will decrease, so that is something to keep in mind when you are selecting an furncae filter for your home.
The most efficient kind of furnace filter you can get would be the electrostatic HEPA (High-Efficiency Particulate Air). These filters will remove 99 percent of the pollutants that are in the air. The great thing about HEPA air filters is that they can be cleaned multiple times and will last you a long time. My recommendation for a good cleaning would be about every 2 months. They will restrict some air flow but if you want to make sure that the air in your home is clean then this is the best choice for you. HEPA filters are used in almost every hospital, dentist office or anywhere else that would require the cleanest air possible.
Another option you could use to keep your air clean are electrostatic precipitators. These types of furnace filters are similar to the electrostatic filters, but they use a power source to supply the charge of the filter. They will restrict air flow, and these types of filters should only be installed by a professional as you will need some other things set up too. These filters will catch stuff as small as .001 micron, which means they are good enough to remove tobacco smoke from the air.
When you are shopping for an furnace filter you will first need to take a measurement on how big the filter is. You can do this by comparing it with the old filter, or by measuring the insert that is right next to the evaporator coils. Most HVAC air filters are 1 inch thick, there are also some that are up to 6 inches in thickness.