Just go to any home improvement store and the choice of home air filters can be dizzying. What's the best one? Should you just get the cheapest? These are just a couple of the questions that make the selection mind-boggling. Let me try to help you de-mystify the air filter dilemma.

Here's a simple way to tell how efficient your current filter is, do this outdoors or with something below the filter so you don't end up with a mess: Hold the filter horizontally, using standard table salt, start pouring the salt through the filter and see how much comes out the other side. If some or all the salt falls through the filter, then you know that the filter will let dust that same size flow through. You should probably upgrade your filter to something more efficient.

There are 3 primary considerations when choosing a household air filter; Size, Material and MERV rating.

Filter Size Size is the easiest factor to ascertain. Simply look at the label of your existing filter to see the dimensions, or just measure it. Most home air filters are 1" thick, but there are a variety of standard width and height dimensions.

Material & MERV Rating Filter efficiencies are given a number from 1-16 called the MERV rating. MERV stands for Minimum Efficiency Reporting Value. This number tells the user, under the least efficient conditions, how well the filter is designed to trap contaminants.

As a basic example, these are some typical MERV ratings and how they correspond to efficiencies. This is only a guide, be sure to read the filter manufacturers' information when shopping for specific filters. Rating Average Filtration Efficiency

MERV 1-4: 60-80%

Fiberglass, Disposable Panel, Washable metal/synthetic, self-charging (Passive)

MERV 5-8: 80-95%

Pleated, Media panel, Cube

MERV 9-12: >95%

Extended pleated

MERV 13-16: >98%

Electronic

Be Careful About High MERV Ratings While a higher MERV number may provide better filtration efficiency, it is very important to understand that too high a MERV filter may also cost you more to operate your heating and air conditioning system. The higher the MERV, the less the air may flow through the system, and the harder the system may need to work. Your goal is to get the right balance between air flow, air filtration level and energy efficiency (we can help you evaluate this).

Think about it this way, the most efficient 'filter' would actually be a piece of plywood that would just trap ALL contaminants (and all the air) from entering your home. That’s maximum air filtration, but would also be the least comfortable way to go.

A safe bet for most systems would be a MERV 6-8. A higher MERV filter should be used on the advice of your Service Experts representative to ensure your system has the capability of moving the proper amount of air through higher efficiency filters. You generally do not want to sacrifice energy-efficiency for filter efficiency; you want a balance of the two. However, if your family suffers from allergies or respiratory problems and needs a high MERV air filter, consider a whole-home air filtration solution that will meet your energy AND filter efficiency needs.

Filtration has changed greatly over the past few years. Originally, home air filters were used in the furnace or air handler only to protect the comfort equipment itself. Today it's a whole new ballgame. Homeowners expect their air filter to save children from a whole host of harmful pollutants, dust mites, and even prevent the need for dusting. I hope this information has helped you understand what filter might be best for your family's needs.