Air Filters – How often Should I Change???

You will see many air filter packaging that says lasts “up to 90” days”. Well, how often should your filter really be changed then? That is a good question because there are many variables that effect how a filter gets dirty depending on your area and lifestyle.

Around here in this neck of the woods, being in the New Braunfels and San Antonio area, if you are using a pleated type air filter in the summer, you should go no more than 30 days. In many applications more often.

Things that effect the length of time air filters will last are:

A. Number of filters you have.

• The more filters you have on one system the more surface area they have and the longer they will each last. Example: you have a filter in each room. Should be able to easily go at least 30 days.

B. Type of filter (standard 1”)

• Pleated filters have more surface area and last longer.
• Some pleated filters have more pleats than others therefore have more surface area than others.
• Polyester fiber plugs up faster due to less surface area but are decent filters. They are far better than floss but not as good as pleated type.
• Floss type let a lot of dust go through and don’t work very well. They are just a little bit better than nothing.  You will pay for it in the long run with high electric bills and repair costs not to mention poor indoor air quality.
• There are other types of filtration available but too many for this article. See future posts.

C. Run time of system.

• The longer the unit runs the more air goes through your filter therefore getting it dirtier quicker meaning more filter changes, but, also cleaning the air more hopefully.

D. Time of year.

• Around here our systems run all the time in the spring, summer, and fall which requires regular filter changes. In the winter, our systems don’t run much as it don’t get too cold so filters tend to last more in the winter and is the only possible time for your filters to last the 30 -90 days we were talking about.

E. If your fan is in the auto or the on position.

• Fan running all the time will cause filter to get dirtier quicker requiring more frequent filter changes maybe twice a month or more. Air quality may be better though as you are filtering more. You can’t filter your air if the system is not running. Many systems have a circulation speed for the fan on position.

F. Doors and windows closed or not.

• Opening doors and windows lets in outside dust and pollens requiring more filtration.

G. Area you live in.

• Some areas are dustier that others. Do you live near a highway or construction zone? Urban or rural? There are many environments in the New Braunfels, Texas area.

H.   Carpeting or Tile.

• Carpet tends to trap dust and can allow your filters to last longer. Tile flooring has no way to hold much dust so filters tend to load up quicker requiring more frequent filter changes.

So… Depending on where you live in this area and how you live can affect the length of time it takes your filter to get plugged up. You want to change your filter before it gets this bad as you will lose efficiency of your system and cause other problems like poor performance, freezing up, compressor damage, and others.

Losing efficiency and capacity due to a dirty filter is entirely preventable and will save you a lot of money on your electric bill. Basically, filters are cheaper than electricity and repair bills, even if you buy good filters.

Get a handle on how long your filter lasts by checking it every week for a while to determine how long it lasts. Do this regularly in the summer and the winter to get on a schedule. Hold it up to the light and see how much light goes through it and you will know when it is time (be sure to put it back in the same direction if you don’t replace it!). You should be able to see light through it. If not then you are past due.  As a rule of thumb, change your filter every month and use a pleated type until you get your schedule down for your application.

MERV Rating- the MERV rating has little to do with how long your filters will last. It has to do with the size particle it will capture. It also has nothing to do with airflow. More on this in another upcoming blog.