Question: How often do you need to change your air conditioning filter?

Changing your air conditioner filter or furnace filter is the most important maintenance task there is if you want to keep your equipment operating at maximum efficiency.  Allowing an air conditioner filter to become so dirty that it begins to restrict air flow can cause evaporator coils to ice up, operating efficiency will decrease and even prevent the unit from maintaining the desired space temperature.

The easy answer to this question is every three months and you should not have any problems.  But there are really many variables to consider when trying to provide an accurate answer to this question.  Often sales people can quote efficiency ratings or MERV ratings and provide you with their standard recommendation but they often don’t really understand how air conditioners operate.

Here are a couple of articles I wrote about this topic.  The first one I wrote today.  The second one I wrote some time ago but found it only after I wrote the one today.  Anyway, they are similar but each provide some different information.  Please leave comments or email questions if you have any.

When To Change Your Air Conditioner Filter
Selecting And Maintaining Your Air Conditioner Filter

Question: What is the MERV Rating of the BoAir 5-Stage electrostatic filter?

The BoAir 5-Stage electrostatic filter like all electrostatic air filters doesn’t have a MERV rating. MERV ratings are only used to rate media types of air filters such as pleated filters and Hepa filters. But if you compare the Arrestance rating of the BoAir 5-Stage electrostatic filter, which is over 95%, the media type filters with similar Arrestance ratings it is equivalent to a Merv 6 or a Merv 8 filter.

A furnace filter with a Merv 8 rating is suitable for use in you air conditioning or heating system if you don’t suffer from allergies but if you require more efficient filtration to manage your allergies I would recommend a Merv 10 to 12 pleated filter.

Question: With regard to pleated air conditioner filters do you think I can go with a MERV 6 filter or do you think I will be better served going with a MERV 8 filter?

A MERV 8 filter will perform better than a MERV 6 filter but the difference will be minimal. If you are not too concerned about dust a MERV 6 filter will do a good enough job. If you are looking for a big improvement in dust control you may want to try a MERV 11 or 12 pleated filter.

Pleated filters in the MERV 5 to 8 range will stop particles of 3 to 10 microns such as some mold spores, fibers, dust mites, some bacteria and fiberglass among other things.

MERV 9 to 12 filters stop particles of 1 to 3 microns such as smoke, bacteria, spray, fumes, coal dust and auto emissions and many other things.