programmable thermostat

The life of a homeowner is filled with choices which can either help or hurt the well-being of your home, especially when it comes to your heating and cooling system. When (hopefully not if!) to schedule your regular maintenance…how to address and fix broken parts…whether/when to invest in new equipment…and the list goes on. One of these important choices is choosing your type of air filter.

Your air filter has 2 purposes:

  1. To protect your HVAC system from being damaged by circulating debris
  2. To improve your indoor air quality by trapping allergens, dust, etc.

Air filters are categorized by their MERV rating, which measures how many particles the filter traps. MERV stands for Minimum Efficiency Reporting Value and is on a scale from 1-20, with 20 being the highest filtration possible. Disposable filters are usually made of fiberglass spun into threads, but can also be made of paper or other fibers. Re-useable filters are made of polypropylene (plastic) or metal mesh. Most home filters range from 8×20 to 20×30 and are 1 inch thick. Higher MERV filters can be up to 5 inches thick which gives them a filter surface area-if you were to unfold all those pleats- of up to 40 square feet!

MERV 1-4


  • Flat, non-pleated
  • Can see through
  • Cheapest, usually costs $5 at box stores

These filters capture the lowest amount of particles, so they do not accomplish either of the 2 filter purposes very well. These filters will only capture the largest particles like hair and some dust…allergens and any smaller particles will go right through these filters and cause damage to your HVAC system as well as circulating throughout your home. On the bright side, these filters are the cheapest and also allow the most airflow through your system.

MERV 5-8


  • Pleated
  • Cannot see through
  • $6-$7 at most box stores

The middle-of-the-road choice for most residential homes (unless a resident has a health concern), these filters capture more dust particles as well as mold spores and pollen.

*Keep in mind that the higher the MERV, the more restricted air flow will be through a filter which could cause other issues. HOWEVER, in our experience this difference in air flow is very minimal and doesn’t cause any major problems. The only time that a higher MERV filter will have a noticeable difference in airflow than a low MERV filter¬†is if you let it get very dirty.

MERV 9-12


Stiles regularly uses MERV 11 or 13 filters in most of our customer’s homes. These filters trap about 80% of particles and are a great choice for those with moderate allergies or respiratory issues.

MERV 13-20


As mentioned above, Stiles uses MERV 13 filters in our customer’s homes though the system must be equipped to handle the thicker filters (4 inches instead of 1 inch). The higher MERV filters are used in hospitals and manufacturing plants (like pharmaceutical manufacturing) since they capture bacteria and viruses.

Reusable Filters


Washable or electrostatic filters are just what their name implies: filters that capture dust particles through static electricity and can be washed and reused.

Advantages of reusable filters:

  • Saves money
  • Environmentally friendly by reducing waste


  • Time/effort of cleaning
  • Cannot capture very large or very small particles or bacteria (MERV usually 1-4)

We recommend the Allergy 2000 washable filters since we have found them to be easier to clean. You should be washing your filter regularly (every month to 3 months) but we have found that coil cleaner works amazingly at taking off all layers of dust and grime. If you have a service agreement, our Stiles techs will clean your filter with coil cleaner so it looks just like new when they come twice a year. If you can maintain your filters in between those deep cleanings, you should be in good shape!

Investing in Savings

Though some homeowners are less than enthusiastic about spending money monthly on filters, keep in mind that a good filter will help your HVAC system last longer with fewer repairs needed as well as keeping your family healthier with fewer doctor visits. As with most choices about home care-the preventative maintenance cost up front is much less than the reactive spending when something goes wrong! Please give us a call if you have any questions about what type of filter is right for your home.