Clean Aire | MyCleanAire.com

Frequently Asked Questions About Home Air Filters

1. Upgrading Filters Or Air Conditioner Filters Is One Of The Least Expensive Things You Can Do To Improve Indoor Air Quality
2. Understanding MERV Ratings
3. Will a neglected filter change jeopardize my equipment performance?
4. Which way do air handler filters go?

1. Upgrading Filters Or Air Conditioner Filters Is One Of The Least Expensive Things You Can Do To Improve Indoor Air Quality

The average person breathes in about 32,000 pints (18,185 liters) of air per day. Those 32,000 pints contain about 1,120,000,000 particles of dust. Most of these particles are 3 microns or smaller.

According to the U.S. Environmental Protection Agency indoor air is two to five times more polluted than outdoor air.

Back to Top ^

2. Understanding MERV Ratings

MERV ratings are used to rate the ability of an air conditioning filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass through the filter.

MERV ratings are determined by adding particles of varying sizes (1-12) into a controlled testing environment. The particles are added upstream of the test filter and a laser particle counter samples the air before it enters the filter and after it leaves the filter. The two particle counts are compared to calculate the Particle Size Efficiency of the tested filter. Once this is determined, a MERV Parameters chart is used to determine the MERV rating.

MERV ratings range from 1 - 16 and measurements are in microns. Some of the common particles related to MERV ratings are pet dander, insecticide dust, smog, dust, viruses, wood, tobacco smoke, spores, bacteria and pollen.

Some of the most common filters found in residential use only have a merv rating of 1 to 4. These are typically disposable panel type filters and do not do a good job of filtering the air because they will not stop particles smaller than 10 microns.

Merv 5 to 8 rated filters are a better choice and are more commonly found in commercial applications. These filters will collect particles as small as 3 microns and are a great choice for home owners also.

Filters with a merv rating of 9 to 12 are used in commercial and industrial applications and will stop particles in the 1 to 3 micron range. When using filters with Merv 9 ratings and above it is important to clean or replace them when recommended by the manufacturer because they will have a negative effect on air flow when they become dirty. This can lead to performance problems and decreased operating efficiency.

What is a MERV Rating?

MERV is an acronym which stands for "Minimum Efficiency Reporting Value" and is the standard developed ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) to rate filter efficiency. The higher the MERV rating the more efficient the filter.

Back to Top ^

3. Will a neglected A/C filter change jeopardize my equipment performance?

A filter that is left in an air conditioning or heating system for extended periods of time can reduce airflow to the point of causing costly equipment breakdowns.It is recommended that the typical household change their filter at least every 3 months.

Back to Top ^

4. Which way do air handler filters go?

When installing a filter or air conditioner filter it is important to know which way they are supposed to go. The reason this is so important is because most air filters are designed to work best when air flow is in a specific direction. With some media type filters it does not really matter and with some it makes a big difference. With most pleated air filters, electrostatic air filters, HEPA filters, fibreglass panel filters and even electronic air filters the direction of air flow is very important. Installing filters the wrong way can have a very negative impact on air flow which reduces the efficiency of the equipment and can also reduce the usable life of the filter.

Usually there are arrows on the frame of the filter that indicates which direction the filter should go. This arrow points in the direction the air is flowing through the duct system. If you are unsure which direction the air will be flowing there are a couple of other points of reference that you can use. You can install the filter so that the arrow is pointing toward the evaporator or if installing in a return grill point the arrow toward the air handler. The arrow always points in the direction of the air handler.

Pleated Air Filters - Sometimes if there is no arrow to indicate the direction of air flow through the filter look at both sides of the filter and see if one side is made a little sturdier than the other. Sometimes a wire mesh is added to one side or the cardboard frame may have cross pieces that make that side appear stronger than the other. Which ever side appears to be sturdier is the back of the filter. You want the air to flow into the filter through the other side first.

Fibreglass Air Filters - Fiberglass panel filters are really not a good filter to use in air conditioning or heating system but if you use them this is what to look for. Usually one site of these filters are a bit denser than the other. The denser side is sometimes even a different color and this side will face in the direction of air flow. In other words, install it so that air will pass through the less dense side first and then through the denser side.

Back to Top ^